Introductory Chapter: Indoor Environmental Quality

*Muhammad Abdul Mujeebu*

### **1. Overview**

The term "indoor environmental quality" (IEQ ) represents a domain that encompasses diverse sub-domains that affect the human life inside a building. These include indoor air quality (IAQ ), lighting, thermal comfort, acoustics, drinking water, ergonomics, electromagnetic radiation, and many related factors [1], as depicted in **Figure 1**. Enhanced environmental quality can improve the quality of life of the occupants, increase the resale value of the building, and minimize the penalties on building owners.

IEQ in offices and other workplaces has a crucial role on the return on investment of businesses. A workplace with high IEQ obviously improves the workers' health and mood, thereby increasing their productivity. Therefore, the additional cost of maintaining high IEQ levels in workplaces will be paid back in a reasonable period and generates additional monetary returns thereafter. It should be noted that buildings being rated as "sustainable and green" do not truly guaranty their compliance with the desired IEQ level [2–5]. Therefore, IEQ should be given specific focus while designing new buildings as well as in building retrofit plans.

**Figure 1.** *IEQ components.*

### **2. Indoor air quality**

Indoor air quality (IAQ ), which depends on airborne contaminants inside a building (or in a broader sense, any other enclosure such as a vehicle or an animal house), is one of the crucial factors that determine the quality of the indoor environment. Providing adequate air quality for the occupants is one of the most important functionalities of a building. Lung cancer (due to radon), Legionnaires' disease, carbon monoxide poisoning, allergy, and asthma are among the serious health implications of poor IAQ [6]. The "sick building syndrome" resulting from inadequate levels of IAQ significantly affects the health and productivity of office employees [7]. Though tremendous efforts are in progress to realize energyefficient, green, and sustainable buildings, maintaining a safe level of IAQ in these buildings is an ongoing challenge. This is due to the fact that many energy-efficient measures in a building (such as reduced outdoor air ventilation rate, increased thermal insulation, and efficient cooling equipment) can have a detrimental impact on IAQ. Thus, alongside energy efficiency and sustainability, there has been a growing concern over air pollution inside buildings. Therefore, attempts to ensure energy efficiency and sustainability in buildings should simultaneously ensure enhanced health, comfort, and productivity of the occupants [6].

There are two major approaches to tackle IAQ issues in buildings: one is to increase the ventilation rate of outdoor air into the building, and the other is to minimize or control the sources of air pollution within and outside the building. Having said that, the first strategy would work only when the outdoor air is clean enough to improve IAQ [7]. The various sources that affect IAQ are, but not limited to, volatile organic compounds, biological pollutants, oxides of carbon and nitrogen, particulate matter, tobacco smoke, radon, mold, formaldehyde, pesticides, and combustion products. Heseltine and Rosen [8] outlined health issues associated with building moisture and biological agents, and the most important health problems identified are respiratory symptoms, allergies, asthma, and perturbation of the immunological system. A recent review [9] has revealed that carpets play a crucial role in IAQ, as they act as a sink for indoor air pollutants such as particles, allergens, and other biological pollutants.

### **3. Thermal comfort**

The term "thermal comfort" refers to a condition that is governed by many environmental and human factors; in other words, physiological, physical, and sociopsychological factors. The environmental factors include air temperature, air velocity, humidity, radiant temperature, and relative humidity, while the major human factors are clothing and metabolic heat. The various other factors include physical health, mental condition, availability of food and drink, and acclimatization. This condition is mostly subjective, which cannot be directly quantified. It has been established that the thermal comfort level is acceptable if at least 80% of the occupants feel comfortable with it. Djongyang et al. [10] and Taleghani et al. [11] provided detailed insights into the thermal comfort in buildings.

#### **4. Lighting comfort**

Visible light falls in a narrow range in the electromagnetic spectrum, between ultraviolet and infrared wavelength ranges. Light has both particle and wave

**3**

*Introductory Chapter: Indoor Environmental Quality DOI: http://dx.doi.org/10.5772/intechopen.83612*

objects and affects the retina.

daylighting.

**5. Acoustic comfort**

cally 20–20,000 Hz.

these characteristics.

properties; when treated as a wave, light has a frequency that depends on the color of the struck surface. For instance, white surface reflects back most of the incident light, while a black surface absorbs most of it. The main aspects of lighting comfort are light level (intensity or brightness), contrast, and glare. The light intensity requirement depends on the type of activity in the building; for instance, operating rooms need a brighter level than living rooms. The term "contrast" refers to the ease of understanding or legibility; higher contrast gives higher clarity (e.g., black text on white paper provides the highest contrast). Glare is always undesirable as it causes a high level of discomfort in viewing the

The visual comfort level is evaluated by means of some established glare metrics or indices; for example, glare probability (DGP) and daylight glare index (DGI) are used for assessing discomfort due to daylighting, while unified glare index (UGI), visual comfort probability (VCP), and CIE glare index (CGI) are employed for measuring the discomfort level of artificial lighting [12–15]. Several other indices are also available, as summarized by Carlucci et al. [12]. Galatioto and Beccali [16] reviewed the various aspects and concerns associated with the assessment of indoor

Building acoustics deals with controlling the quality of sound inside a building. It has two parts, namely, room acoustics and building acoustics, which deal with the sound propagation within a room and between rooms (through walls, doors, and floors), respectively. While the room acoustics focuses mainly on the sound quality (e.g., easy communication and high level of intelligibility in office spaces), the building acoustics is concerned with the "unsolicited" sound (e.g., the noise in a room should not be a nuisance to other rooms). The acoustic comfort in a building has a crucial impact on the health, well-being, communication, and productivity of the occupants. The acoustic comfort can be affected by factors such as the geometry and volume of a space, generation of sound within or outside the space, airborne noise transmission, impact noise, and the acoustic characteristics (absorption, transmission, and reflection of sound) of the interior surfaces. The measuring unit of sound intensity is decibels (dB), and of sound pitch is hertz (Hz). The comfortable range of sound for humans is typi-

The common parameters used for evaluating the acoustic performance of a building are reverberation time (RT), sound pressure level (SPL), early decay time (EDT), clarity (C50 for speech and C80 for music), sound definition or speech intelligibility (D or D50), and speech transmission index (STI). RT is defined as the time for the sound level to decay by 60 dB after a sound source has been switched off. EDT is similar to RT, but it is the initial rate of sound decay in a room, measured as the slope of a line 0–10 dB decay below the maximum sound level. D50 is defined as the ratio of the early received sound energy (0–50 ms after direct sound arrival) to the total received energy. Clarity is defined as the ratio of the energy in the early sound (received in the first 80 ms) to that in the reverberant sound. STI is a measure of speech transmission quality, which indicates the degree to which a transmission channel degrades speech intelligibility. STI ranges from 0 to 1; a speech transferred through a channel with STI of 1 is perfectly intelligible, but the intelligibility reduces as the STI approaches zero. International standards and guidelines (e.g., ISO 18233) are available for the measurement of

*Introductory Chapter: Indoor Environmental Quality DOI: http://dx.doi.org/10.5772/intechopen.83612*

*Indoor Environmental Quality*

**2. Indoor air quality**

Indoor air quality (IAQ ), which depends on airborne contaminants inside a building (or in a broader sense, any other enclosure such as a vehicle or an animal house), is one of the crucial factors that determine the quality of the indoor environment. Providing adequate air quality for the occupants is one of the most important functionalities of a building. Lung cancer (due to radon), Legionnaires' disease, carbon monoxide poisoning, allergy, and asthma are among the serious health implications of poor IAQ [6]. The "sick building syndrome" resulting from inadequate levels of IAQ significantly affects the health and productivity of office employees [7]. Though tremendous efforts are in progress to realize energyefficient, green, and sustainable buildings, maintaining a safe level of IAQ in these buildings is an ongoing challenge. This is due to the fact that many energy-efficient measures in a building (such as reduced outdoor air ventilation rate, increased thermal insulation, and efficient cooling equipment) can have a detrimental impact on IAQ. Thus, alongside energy efficiency and sustainability, there has been a growing concern over air pollution inside buildings. Therefore, attempts to ensure energy efficiency and sustainability in buildings should simultaneously ensure enhanced

There are two major approaches to tackle IAQ issues in buildings: one is to increase the ventilation rate of outdoor air into the building, and the other is to minimize or control the sources of air pollution within and outside the building. Having said that, the first strategy would work only when the outdoor air is clean enough to improve IAQ [7]. The various sources that affect IAQ are, but not limited to, volatile organic compounds, biological pollutants, oxides of carbon and nitrogen, particulate matter, tobacco smoke, radon, mold, formaldehyde, pesticides, and combustion products. Heseltine and Rosen [8] outlined health issues associated with building moisture and biological agents, and the most important health problems identified are respiratory symptoms, allergies, asthma, and perturbation of the immunological system. A recent review [9] has revealed that carpets play a crucial role in IAQ, as they act as a sink for indoor air pollutants such as particles,

The term "thermal comfort" refers to a condition that is governed by many environmental and human factors; in other words, physiological, physical, and sociopsychological factors. The environmental factors include air temperature, air velocity, humidity, radiant temperature, and relative humidity, while the major human factors are clothing and metabolic heat. The various other factors include physical health, mental condition, availability of food and drink, and acclimatization. This condition is mostly subjective, which cannot be directly quantified. It has been established that the thermal comfort level is acceptable if at least 80% of the occupants feel comfortable with it. Djongyang et al. [10] and Taleghani et al. [11] provided detailed insights into the thermal comfort in

Visible light falls in a narrow range in the electromagnetic spectrum, between

ultraviolet and infrared wavelength ranges. Light has both particle and wave

health, comfort, and productivity of the occupants [6].

allergens, and other biological pollutants.

**3. Thermal comfort**

**2**

buildings.

**4. Lighting comfort**

properties; when treated as a wave, light has a frequency that depends on the color of the struck surface. For instance, white surface reflects back most of the incident light, while a black surface absorbs most of it. The main aspects of lighting comfort are light level (intensity or brightness), contrast, and glare. The light intensity requirement depends on the type of activity in the building; for instance, operating rooms need a brighter level than living rooms. The term "contrast" refers to the ease of understanding or legibility; higher contrast gives higher clarity (e.g., black text on white paper provides the highest contrast). Glare is always undesirable as it causes a high level of discomfort in viewing the objects and affects the retina.

The visual comfort level is evaluated by means of some established glare metrics or indices; for example, glare probability (DGP) and daylight glare index (DGI) are used for assessing discomfort due to daylighting, while unified glare index (UGI), visual comfort probability (VCP), and CIE glare index (CGI) are employed for measuring the discomfort level of artificial lighting [12–15]. Several other indices are also available, as summarized by Carlucci et al. [12]. Galatioto and Beccali [16] reviewed the various aspects and concerns associated with the assessment of indoor daylighting.

### **5. Acoustic comfort**

Building acoustics deals with controlling the quality of sound inside a building. It has two parts, namely, room acoustics and building acoustics, which deal with the sound propagation within a room and between rooms (through walls, doors, and floors), respectively. While the room acoustics focuses mainly on the sound quality (e.g., easy communication and high level of intelligibility in office spaces), the building acoustics is concerned with the "unsolicited" sound (e.g., the noise in a room should not be a nuisance to other rooms). The acoustic comfort in a building has a crucial impact on the health, well-being, communication, and productivity of the occupants. The acoustic comfort can be affected by factors such as the geometry and volume of a space, generation of sound within or outside the space, airborne noise transmission, impact noise, and the acoustic characteristics (absorption, transmission, and reflection of sound) of the interior surfaces. The measuring unit of sound intensity is decibels (dB), and of sound pitch is hertz (Hz). The comfortable range of sound for humans is typically 20–20,000 Hz.

The common parameters used for evaluating the acoustic performance of a building are reverberation time (RT), sound pressure level (SPL), early decay time (EDT), clarity (C50 for speech and C80 for music), sound definition or speech intelligibility (D or D50), and speech transmission index (STI). RT is defined as the time for the sound level to decay by 60 dB after a sound source has been switched off. EDT is similar to RT, but it is the initial rate of sound decay in a room, measured as the slope of a line 0–10 dB decay below the maximum sound level. D50 is defined as the ratio of the early received sound energy (0–50 ms after direct sound arrival) to the total received energy. Clarity is defined as the ratio of the energy in the early sound (received in the first 80 ms) to that in the reverberant sound. STI is a measure of speech transmission quality, which indicates the degree to which a transmission channel degrades speech intelligibility. STI ranges from 0 to 1; a speech transferred through a channel with STI of 1 is perfectly intelligible, but the intelligibility reduces as the STI approaches zero. International standards and guidelines (e.g., ISO 18233) are available for the measurement of these characteristics.

Extensive researches are in progress, on the acoustic comfort in buildings. In recent works, Tong et al. [17] studied the acoustical performance of classrooms and laboratories in a public school exposed to traffic environment, while Jeong et al. [18] focused on the acoustic design and evaluation of a concert hall. Tan et al. [19] introduced application of building information modeling to improve indoor acoustic performance. Few other studies include those reported by Lam et al. [20], Imran et al. [21], and Renterghem [22].

### **6. Ergonomics**

Ergonomics deals with the design of objects, systems, and environment, in a manner that ensures human comfort. In fact, ergonomics encompasses all components of IEQ, simply because the prime objective of IEQ is human health and comfort. It covers diverse disciplines such as anatomy, physiology, psychology, and design. An indoor ergonomist should be specialized in the interrelationship between the human mind and body and the various aspects of a building such as architecture, interior design, building services, structure, materials, and microclimate. In general, environmental ergonomics deals with the interaction between people and their physical environment with particular importance on thermal comfort, lighting, noise, and vibration. Similar to ergonomics in a residential environment, ergonomics in offices and workplace is also a scientific discipline and a topic of research. Edmonds [23] defines the following factors that affect the workplace ergonomics: tasks, tools, equipment, area and space, environment, and organizational pattern. The Southeast Asian Network of Ergonomics Societies (SEANES) has introduced ergonomic checkpoints for indoor and outdoor workplaces for the purpose of motivating workers to recognize hazards in the work environment and adopt precautionary measures accordingly [24]. Similarly, Ushada et al. [25] developed environmental ergonomic control system for small and medium sized, by using worker workload and workstation temperature difference.

### **7. Electromagnetic field and radiation**

Electromagnetic field is created by moving electric charges, microwaves, radio waves, electrical currents, and transformers. The low-frequency electromagnetic radiation prevailing mostly in indoors (due to electrical appliances, computers, wireless devices, etc.) can have detrimental effect on human health, and there are international regulations to deal with this problem (e.g., International Radiation Protection Association (IRPA)) [26]. Most of the regulations agree that exposure to electromagnetic field beyond the safe range of 0–300 Hz is harmful for the human body [27]. The possibility of health hazards such as acute lymphoblastic leukemia in children due to electromagnetic field exposure was well established decades ago [28] and continues to be a significant topic of research [26, 29–31].

#### **8. Water quality**

Adequate, safe, and accessible supply of drinking water is vital for the sustenance of human life especially in indoor environments where access to natural sources of water such as wells, ponds, rivers, and lakes is limited. Drinking water

**5**

[53, 54].

*Introductory Chapter: Indoor Environmental Quality DOI: http://dx.doi.org/10.5772/intechopen.83612*

ability [32].

identified.

**9. IEQ research trends**

**9.1 IEQ of common buildings**

quality has a direct impact on human health. Infants, young children, weak and elderly people, and those who live in unhygienic environment are largely prone to waterborne deceases [32]. There is no universally applicable legislative framework for the implementation of standards to maintain drinking water quality. An approach that works in one country or region may not be suitable for other countries. Therefore, each country should develop its own legislation according to its requirements and capacity for implementation. However, while developing standards, the most common aspects that need to be taken into account are microbial safety, chemical safety, radiological safety, disinfection, and accept-

A huge number of literatures are available on the research on various aspects of IEQ, and a comprehensive review of these literatures is beyond the scope of this chapter. Many researchers have compiled them in their review articles [7, 33–42]. However, a brief overview of the exemplary researches is presented here. Most of the researches were on post-occupancy evaluation (POE) on IEQ of different types of common buildings (e.g., healthcare, office, educational, residential, etc.), through field measurements and user satisfaction surveys, while many other researchers were interested on POE of sustainable and green buildings. In these researches, the findings are usually compared with the prevailing local or global (as applicable) standards, and recommendations are made to address the issues

Reynolds et al. [43] measured the physical, mechanical, and environmental factors affecting IEQ of office buildings in the United States (US). The measurements included endotoxin, total bioaerosols, and psychosocial parameters. Addressing the impact of IEQ on the occupant's productivity in offices, Kang et al. [44] investigated open-plan research offices in 19 Chinese universities by conducting survey on 231 subjects. The study identified five factors that significantly affected the office productivity, which are layout, air quality, thermal comfort, lighting, and acoustic comfort, where the acoustic comfort had the maximum impact. In a similar study [45], experiments were performed on the effect of indoor temperature on the IEQ user perception and productivity in office buildings, by choosing 9 females and 12 males. The parameters measured were air temperature, globe temperature, relative humidity, carbon dioxide (CO2) concentration, and lighting and noise comforts. The indoor air temperature was varied by keeping the other IEQ parameters fixed. It was shown that the thermal environment had a significant impact on the thermal comfort and other IEQ factors. Kim et al. [46] focused on the impact of IEQ and work stress on the physiological responses of office workers and concluded that the most noticeable result of the experiment in this study is that a high CO2 concentration and work stress could detrimentally influence the physiological and physiological responses, leading to abnormal variations in blood pressure. Similar studies on the effect of IEQ on office workers' performance are those reported by Haapakangas et al. [47], Suk [14], Zuo and Malone Beach [48], Ali et al. [49], Huang et al. [50], Frontczak et al. [51], Wong et al. [52], and Kosonen and Tan

*Introductory Chapter: Indoor Environmental Quality DOI: http://dx.doi.org/10.5772/intechopen.83612*

quality has a direct impact on human health. Infants, young children, weak and elderly people, and those who live in unhygienic environment are largely prone to waterborne deceases [32]. There is no universally applicable legislative framework for the implementation of standards to maintain drinking water quality. An approach that works in one country or region may not be suitable for other countries. Therefore, each country should develop its own legislation according to its requirements and capacity for implementation. However, while developing standards, the most common aspects that need to be taken into account are microbial safety, chemical safety, radiological safety, disinfection, and acceptability [32].

### **9. IEQ research trends**

*Indoor Environmental Quality*

**6. Ergonomics**

Imran et al. [21], and Renterghem [22].

workstation temperature difference.

topic of research [26, 29–31].

**8. Water quality**

**7. Electromagnetic field and radiation**

Extensive researches are in progress, on the acoustic comfort in buildings. In recent works, Tong et al. [17] studied the acoustical performance of classrooms and laboratories in a public school exposed to traffic environment, while Jeong et al. [18] focused on the acoustic design and evaluation of a concert hall. Tan et al. [19] introduced application of building information modeling to improve indoor acoustic performance. Few other studies include those reported by Lam et al. [20],

Ergonomics deals with the design of objects, systems, and environment, in a manner that ensures human comfort. In fact, ergonomics encompasses all components of IEQ, simply because the prime objective of IEQ is human health and comfort. It covers diverse disciplines such as anatomy, physiology, psychology, and design. An indoor ergonomist should be specialized in the interrelationship between the human mind and body and the various aspects of a building such as architecture, interior design, building services, structure, materials, and microclimate. In general, environmental ergonomics deals with the interaction between people and their physical environment with particular importance on thermal comfort, lighting, noise, and vibration. Similar to ergonomics in a residential environment, ergonomics in offices and workplace is also a scientific discipline and a topic of research. Edmonds [23] defines the following factors that affect the workplace ergonomics: tasks, tools, equipment, area and space, environment, and organizational pattern. The Southeast Asian Network of Ergonomics Societies (SEANES) has introduced ergonomic checkpoints for indoor and outdoor workplaces for the purpose of motivating workers to recognize hazards in the work environment and adopt precautionary measures accordingly [24]. Similarly, Ushada et al. [25] developed environmental ergonomic control system for small and medium sized, by using worker workload and

Electromagnetic field is created by moving electric charges, microwaves, radio waves, electrical currents, and transformers. The low-frequency electromagnetic radiation prevailing mostly in indoors (due to electrical appliances, computers, wireless devices, etc.) can have detrimental effect on human health, and there are international regulations to deal with this problem (e.g., International Radiation Protection Association (IRPA)) [26]. Most of the regulations agree that exposure to electromagnetic field beyond the safe range of 0–300 Hz is harmful for the human body [27]. The possibility of health hazards such as acute lymphoblastic leukemia in children due to electromagnetic field exposure was well established decades ago [28] and continues to be a significant

Adequate, safe, and accessible supply of drinking water is vital for the sustenance of human life especially in indoor environments where access to natural sources of water such as wells, ponds, rivers, and lakes is limited. Drinking water

**4**

A huge number of literatures are available on the research on various aspects of IEQ, and a comprehensive review of these literatures is beyond the scope of this chapter. Many researchers have compiled them in their review articles [7, 33–42]. However, a brief overview of the exemplary researches is presented here. Most of the researches were on post-occupancy evaluation (POE) on IEQ of different types of common buildings (e.g., healthcare, office, educational, residential, etc.), through field measurements and user satisfaction surveys, while many other researchers were interested on POE of sustainable and green buildings. In these researches, the findings are usually compared with the prevailing local or global (as applicable) standards, and recommendations are made to address the issues identified.

#### **9.1 IEQ of common buildings**

Reynolds et al. [43] measured the physical, mechanical, and environmental factors affecting IEQ of office buildings in the United States (US). The measurements included endotoxin, total bioaerosols, and psychosocial parameters. Addressing the impact of IEQ on the occupant's productivity in offices, Kang et al. [44] investigated open-plan research offices in 19 Chinese universities by conducting survey on 231 subjects. The study identified five factors that significantly affected the office productivity, which are layout, air quality, thermal comfort, lighting, and acoustic comfort, where the acoustic comfort had the maximum impact. In a similar study [45], experiments were performed on the effect of indoor temperature on the IEQ user perception and productivity in office buildings, by choosing 9 females and 12 males. The parameters measured were air temperature, globe temperature, relative humidity, carbon dioxide (CO2) concentration, and lighting and noise comforts. The indoor air temperature was varied by keeping the other IEQ parameters fixed. It was shown that the thermal environment had a significant impact on the thermal comfort and other IEQ factors. Kim et al. [46] focused on the impact of IEQ and work stress on the physiological responses of office workers and concluded that the most noticeable result of the experiment in this study is that a high CO2 concentration and work stress could detrimentally influence the physiological and physiological responses, leading to abnormal variations in blood pressure. Similar studies on the effect of IEQ on office workers' performance are those reported by Haapakangas et al. [47], Suk [14], Zuo and Malone Beach [48], Ali et al. [49], Huang et al. [50], Frontczak et al. [51], Wong et al. [52], and Kosonen and Tan [53, 54].

Almeida and De Freitas [55] performed onsite measurements of temperature, relative humidity, CO2 concentration, and ventilation rates in the classrooms of nine retrofitted and non-retrofitted school buildings in Portugal. The measurements were done during winter, mid-season, and summer conditions. In their observations, the non-retrofitted schools lack in the desired IEQ level, while retrofitted buildings did not have mechanical ventilation systems. Shan et al. [56] investigated the influence of indoor thermal condition and IAQ on students' health and performance through life cycle costing (LCC) approach, by considering two university classrooms. In the proposed LCC approach, metrics were defined for students' health (or well-being) and performance, which were subsequently translated into monetary values to quantify the impact of IEQ. The indicators considered for health and performance were sick leave and students' grade achievement, respectively. The findings of this study indicated the significance of incorporating students' health and performance into the design and operation of educational buildings. Few other researches focusing on educational buildings are those of Kim et al. [57], Vilčeková et al. [58], Jamaludin et al. [59], De Giuli et al. [60], and Nasir et al. [61].

Lai et al. [62] developed an IEQ assessment model for residential buildings in Hong Kong. The empirical model developed by using the data collected from 125 occupants from 32 residential buildings was useful to assess the acceptance level in terms of operative temperature, CO2 concentration, and acoustic and lighting comforts. The study revealed that both thermal and acoustic comforts were the decisive contributors, while IAQ was the least. Huang et al. [63] studied the effect of IEQ of long-term care (LTC) facilities on the occupants' behavior, through survey. Garcia et al. [64] performed retrospective descriptive secondary analyses on the data collected (air exchange rates, temperature, and humidity) from indoor, outdoor, and personal air in residential buildings. Addressing the IEQ of healthcare buildings, Andrade et al. [65] performed user perception survey on hospital buildings in Portugal, considering physical and social aspects. De Giuli et al. [66] conducted survey and field measurements of three medical wards in a general hospital in Italy.

#### **9.2 IEQ of sustainable and green buildings**

As already mentioned, the IEQ level of sustainable and green buildings has been a concern of many researchers. Choi [67] proposed an explanatory model to understand the relationships among the occupants' perceptions on the IEQ level, overall facility, productivity, and sustainability ethic, in sustainable buildings. Hwang and Kim [68] performed post-occupancy evaluation (POE) of open offices in a Korean building that was certified as "1st Grade Building" Green. The studied parameters were indoor temperature, relative humidity, vertical temperature distribution, air velocity, predicted mean vote (PMV), radiant temperature, outdoor temperature, and humidity. Measurements were also done on the major indoor air contaminants, illuminance, and SPL. An online survey was also conducted among the occupants to know their perception on the IEQ level. The performance of this building was found to be satisfactory in terms of PMV and lighting, while it was weak for IAQ and acoustic comfort. Ravindu et al. [69] explored the IEQ level of a LEED-certified factory building in Sri Lanka, through questionnaire survey. They found that the building was performing low with regard to thermal comfort, ventilation, and ability to control indoor the environment. Altomonte et al. [3] studied the occupant satisfaction on IEQ in LEED- and BREEAM-certified office buildings and highlighted the importance of incorporating IEQ in the criteria for sustainable and green building certifications.

**7**

*Introductory Chapter: Indoor Environmental Quality DOI: http://dx.doi.org/10.5772/intechopen.83612*

Indoor environmental quality is a very important scientific domain that deals with various aspects that govern the health, comfort, and productivity of the occupants and determine the value of a building. However, even though there is increasing awareness on the demand for sustainable, green, and highperformance buildings, ensuring the desired level of IEQ is often not given the deserving care. Consequently, most of the sustainable and green buildings lack in complying with the IEQ requirements. The building owners should rewrite their mindset to take into account the enormous potential for monetary returns and health benefits through improving the IEQ of the building. The following good practices are generally recommended to ensure a comfortable level of

• Follow scientific practices of design, construction, renovation, operation, and

• Enhance the esthetics and indoor environment by proper integration of natural

• Minimize the dependence of artificial lighting and electrical equipment such as air conditioner, elevator, and fans, with a view to improve human health and

• Ensure thermal comfort through proper design of the interior and microclimate.

• Facilitate proper ventilation and maintain acceptable air quality, by following

• Adopt proper design and maintenance of HVAC system, and proper design and construction of the envelope, to prevent mold, fungi, airborne bacteria, and

• Minimize the spread of pathogens by minimizing exposure to washrooms and

• Avoid using products and materials, which contain harmful ingredients (such

• Ensure noise comfort and privacy, by suitably adopting the materials for walls,

• Avoid unpleasant odors through selective use of products, regular and safe waste disposal, careful selection of cleaning products, isolation of contami-

• Establish a comfortable and healthy indoor lighting, through optimum integration of artificial and natural lightings, and use of energy-efficient, user-

floors, and ceiling, and other standard means for acoustic comfort.

maintenance, in compliance with the international standards.

• Adopt "source control" by minimizing the causes that lead to poor IEQ.

**10. Concluding remarks**

and man-made facilities.

standard guidelines.

radon.

minimize energy consumption.

by proper maintenance procedures.

as formaldehyde) and produce harmful emissions.

nants, prohibition of smoking, and related measures.

friendly, and eco-friendly artificial lighting.

IEQ:

## **10. Concluding remarks**

*Indoor Environmental Quality*

Almeida and De Freitas [55] performed onsite measurements of temperature, relative humidity, CO2 concentration, and ventilation rates in the classrooms of nine retrofitted and non-retrofitted school buildings in Portugal. The measurements were done during winter, mid-season, and summer conditions. In their observations, the non-retrofitted schools lack in the desired IEQ level, while retrofitted buildings did not have mechanical ventilation systems. Shan et al. [56] investigated the influence of indoor thermal condition and IAQ on students' health and performance through life cycle costing (LCC) approach, by considering two university classrooms. In the proposed LCC approach, metrics were defined for students' health (or well-being) and performance, which were subsequently translated into monetary values to quantify the impact of IEQ. The indicators considered for health and performance were sick leave and students' grade achievement, respectively. The findings of this study indicated the significance of incorporating students' health and performance into the design and operation of educational buildings. Few other researches focusing on educational buildings are those of Kim et al. [57], Vilčeková

et al. [58], Jamaludin et al. [59], De Giuli et al. [60], and Nasir et al. [61].

**9.2 IEQ of sustainable and green buildings**

sustainable and green building certifications.

Lai et al. [62] developed an IEQ assessment model for residential buildings in Hong Kong. The empirical model developed by using the data collected from 125 occupants from 32 residential buildings was useful to assess the acceptance level in terms of operative temperature, CO2 concentration, and acoustic and lighting comforts. The study revealed that both thermal and acoustic comforts were the decisive contributors, while IAQ was the least. Huang et al. [63] studied the effect of IEQ of long-term care (LTC) facilities on the occupants' behavior, through survey. Garcia et al. [64] performed retrospective descriptive secondary analyses on the data collected (air exchange rates, temperature, and humidity) from indoor, outdoor, and personal air in residential buildings. Addressing the IEQ of healthcare buildings, Andrade et al. [65] performed user perception survey on hospital buildings in Portugal, considering physical and social aspects. De Giuli et al. [66] conducted survey and field measurements of three medical wards in a general hospital in Italy.

As already mentioned, the IEQ level of sustainable and green buildings has been a concern of many researchers. Choi [67] proposed an explanatory model to understand the relationships among the occupants' perceptions on the IEQ level, overall facility, productivity, and sustainability ethic, in sustainable buildings. Hwang and Kim [68] performed post-occupancy evaluation (POE) of open offices in a Korean building that was certified as "1st Grade Building" Green. The studied parameters were indoor temperature, relative humidity, vertical temperature distribution, air velocity, predicted mean vote (PMV), radiant temperature, outdoor temperature, and humidity. Measurements were also done on the major indoor air contaminants, illuminance, and SPL. An online survey was also conducted among the occupants to know their perception on the IEQ level. The performance of this building was found to be satisfactory in terms of PMV and lighting, while it was weak for IAQ and acoustic comfort. Ravindu et al. [69] explored the IEQ level of a LEED-certified factory building in Sri Lanka, through questionnaire survey. They found that the building was performing low with regard to thermal comfort, ventilation, and ability to control indoor the environment. Altomonte et al. [3] studied the occupant satisfaction on IEQ in LEED- and BREEAM-certified office buildings and highlighted the importance of incorporating IEQ in the criteria for

**6**

Indoor environmental quality is a very important scientific domain that deals with various aspects that govern the health, comfort, and productivity of the occupants and determine the value of a building. However, even though there is increasing awareness on the demand for sustainable, green, and highperformance buildings, ensuring the desired level of IEQ is often not given the deserving care. Consequently, most of the sustainable and green buildings lack in complying with the IEQ requirements. The building owners should rewrite their mindset to take into account the enormous potential for monetary returns and health benefits through improving the IEQ of the building. The following good practices are generally recommended to ensure a comfortable level of IEQ:

## **Author details**

Muhammad Abdul Mujeebu Department of Building Engineering, College of Architecture and Planning, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia

\*Address all correspondence to<EMAIL_ADDRESS>
© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**9**

*Introductory Chapter: Indoor Environmental Quality DOI: http://dx.doi.org/10.5772/intechopen.83612*

Health Organization Regional Office for

[9] Becher R, Øvrevik J, Schwarze PE, Nilsen S, Hongslo JK, Bakke JV. Do carpets impair indoor air quality and cause adverse health outcomes: A review. International Journal of Environmental Research and Public

[10] Djongyang N, Tchinda R, Njomo D. Thermal comfort: A review paper. Renewable and Sustainable Energy Reviews. 2010;**14**(9):2626-2640

[11] Taleghani M, Tenpierik M, Kurvers S, Van Den Dobbelsteen A. A review into thermal comfort in buildings. Renewable and Sustainable Energy

[12] Carlucci S, Causone F, De Rosa F, Pagliano L. A review of indices for assessing visual comfort with a view to their use in optimization processes to support building integrated design. Renewable and Sustainable Energy Reviews. 2015;**47**(7491):1016-1033

[13] Xue P, Mak CM, Huang Y. Quantification of luminous comfort with dynamic daylight metrics in residential buildings. Energy and Buildings. 2016;**117**:99-108

[14] Suk JY. Luminance and vertical eye illuminance thresholds for occupants' visual comfort in daylit office environments. Building and Environment. 2019;**148**:107-115

[15] Suk JY, Schiler M, Kensek K. Absolute glare factor and relative glare factor based metric: Predicting and quantifying levels of daylight glare in office space. Energy and Buildings.

[16] Galatioto A, Beccali M. Aspects and issues of daylighting assessment:

2016;**130**:8-19

Europe; 2009

Health. 2018;**15**(2):E184

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[2] Spengler JD, Chen QY. Indoor air quality factors in designing a healthy building. Annual Review of Energy and the Environment. Amsterdam, Netherlands: Elsevier

[3] Altomonte S, Saadouni S, Kent MG, Schiavon S. Satisfaction with indoor environmental quality in BREEAM and non-BREEAM certified office buildings. Architectural Science Review.

Rismanchi B. Ten questions concerning

[5] Holmgren M, Kabanshi A, Sörqvist P.

buildings: Distinguishing physical and psychological factors. Building and Environment. 2017;**114**:140-147

[6] Persily AK, Emmerich SJ. Indoor air quality in sustainable, energy efficient buildings. HVAC & R Research.

[7] Al horr Y, Arif M, Katafygiotou M, Mazroei A, Kaushik A, Elsarrag E. Impact of indoor environmental quality on occupant well-being and comfort: A review of the literature. International Journal of Sustainable Built

Environment. 2016;**5**(1):1-11

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B.V; 2000;**25**:567-601

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[4] Steinemann A, Wargocki P,

green buildings and indoor air quality. Building and Environment.

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*Introductory Chapter: Indoor Environmental Quality DOI: http://dx.doi.org/10.5772/intechopen.83612*

### **References**

*Indoor Environmental Quality*

indoor environment.

facilities.

**8**

**Author details**

Muhammad Abdul Mujeebu

provided the original work is properly cited.

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

Department of Building Engineering, College of Architecture and Planning, Imam

Abdulrahman Bin Faisal University, Dammam, Saudi Arabia

\*Address all correspondence to<EMAIL_ADDRESS>
• Maintain availability and accessibility of safe and clean drinking water in

• Restrict and be aware of exposure to electromagnetic field and radiation, in the

• Ensure indoor ergonomic quality by providing ergonomic furniture and other

• Regularly conduct occupant surveys and post-occupancy evaluations.

compliance with the water quality standards.

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[4] Steinemann A, Wargocki P, Rismanchi B. Ten questions concerning green buildings and indoor air quality. Building and Environment. 2017;**112**(2017):351-358

[5] Holmgren M, Kabanshi A, Sörqvist P. Occupant perception of 'green' buildings: Distinguishing physical and psychological factors. Building and Environment. 2017;**114**:140-147

[6] Persily AK, Emmerich SJ. Indoor air quality in sustainable, energy efficient buildings. HVAC & R Research. 2012;**18**(1-2):4-20

[7] Al horr Y, Arif M, Katafygiotou M, Mazroei A, Kaushik A, Elsarrag E. Impact of indoor environmental quality on occupant well-being and comfort: A review of the literature. International Journal of Sustainable Built Environment. 2016;**5**(1):1-11

[8] Heseltine E, Rosen J. WHO Guidelines for Indoor Air Quality: Dampness and Mould. Germany: World Health Organization Regional Office for Europe; 2009

[9] Becher R, Øvrevik J, Schwarze PE, Nilsen S, Hongslo JK, Bakke JV. Do carpets impair indoor air quality and cause adverse health outcomes: A review. International Journal of Environmental Research and Public Health. 2018;**15**(2):E184

[10] Djongyang N, Tchinda R, Njomo D. Thermal comfort: A review paper. Renewable and Sustainable Energy Reviews. 2010;**14**(9):2626-2640

[11] Taleghani M, Tenpierik M, Kurvers S, Van Den Dobbelsteen A. A review into thermal comfort in buildings. Renewable and Sustainable Energy Reviews. 2013;**26**:201-215

[12] Carlucci S, Causone F, De Rosa F, Pagliano L. A review of indices for assessing visual comfort with a view to their use in optimization processes to support building integrated design. Renewable and Sustainable Energy Reviews. 2015;**47**(7491):1016-1033

[13] Xue P, Mak CM, Huang Y. Quantification of luminous comfort with dynamic daylight metrics in residential buildings. Energy and Buildings. 2016;**117**:99-108

[14] Suk JY. Luminance and vertical eye illuminance thresholds for occupants' visual comfort in daylit office environments. Building and Environment. 2019;**148**:107-115

[15] Suk JY, Schiler M, Kensek K. Absolute glare factor and relative glare factor based metric: Predicting and quantifying levels of daylight glare in office space. Energy and Buildings. 2016;**130**:8-19

[16] Galatioto A, Beccali M. Aspects and issues of daylighting assessment: A review study. Renewable and Sustainable Energy Reviews. 2016;**66**:852-860

[17] Tong Y, Abu Bakar H, Sari KM, Ewon U, Labeni M, Fauzan N. Effect of urban noise to the acoustical performance of the secondary school's learning spaces—A case study in Batu Pahat. IOP Conference Series: Materials Science and Engineering. 2017;**271**(012029):1-8

[18] Jeong K , Hong T, Kim SH, Kim J, Lee S. "Acoustic design of a classical concert hall and evaluation of its acoustic performance—A case study," Preprint, vol.<PHONE_NUMBER>, no. May, pp. 1-12, 2018

[19] Tan Y, Fang Y, Zhou T, Wang Q, Cheng JCP, Kong H. Improve indoor acoustics performance by using building information modeling. In: 34th International Symposium on Automation and Robotics in Construction (ISARC 2017); 28 June-1 July 2017; Taipei, Taiwan. 2017

[20] Lam A, Hodgson M, Prodi N, Visentin C. Effects of classroom acoustics on speech intelligibility and response time: A comparison between native and non-native listeners. Building Acoustics. 2018;**25**(1):35-42

[21] Imran M, Heimes A, Vorländer M. Auralization of airborne sound transmission for coupled rooms in virtual reality. In: 44th Annual Conference on Acoustics (DAGA 2018); 19-22 March 2018; Munich, Germany. 2018

[22] Van Renterghem T. Improving the noise reduction by green roofs due to solar panels and substrate shaping. Building Acoustics. 2018;**25**(3):219-232

[23] Edmonds J. Overview of human factors engineering. In: Human Factors in the Chemical and Process Industries. Amsterdam, Netherlands: Elsevier B.V., Elsevier Inc.; 2016. pp. 153-167

[24] Khalid H, Kogi K, Helander M. Ergonomics intervention of workplaces using SEANES ergonomic checkpoints. In: 20th Congress of the International Ergonomics Association (IEA 2018); 2018. pp. 1125-1134

[25] Ushada M, Suyantohadi A, Khuriyati N, Okayama T. Identification of environmental ergonomics control system for Indonesian SMEs. In: 3rd International Conference on Control, Automation and Robotics; 24-26 April 2017; Nagoya, Japan. 2017. pp. 453-456

[26] Fayed I, Bedda M. Electromagnetic radiation and its effects on human beings: Survey and environmental recommendations. In: 15th Scientific Symposium for Hajj, Umrah and Madinah visit—Scientific Portal for 1436AH; 27-28 May 2015; Saudi Arabia. 2015. pp. 35-47

[27] Valberg PA, van Deventer TE, Repacholi MH. Workgroup report: Base stations and wireless networks- -radiofrequency (RF) exposures and health consequences. Environmental Health Perspectives. 2007;**115**(3):416

[28] Linet MS, Hatch EE, Kleinerman RA, Robison LL, Kaune WT, Friedman DR, et al. Residential exposure to magnetic fields and acute lymphoblastic leukemia in children. The New England Journal of Medicine. 1997;**337**(1):1-8

[29] Kheifets L, Repacholi M, Saunders R, Van Deventer E. The sensitivity of children to electromagnetic fields. Pediatrics. 2005;**116**:303-313

[30] Verloock L, Joseph W, Vermeeren G, Martens L. Procedure for assessment of general public exposure from WLAN in offices and in wireless sensor network testbed. Health Physics. 2010;**98**(4):628-638

**11**

*Introductory Chapter: Indoor Environmental Quality DOI: http://dx.doi.org/10.5772/intechopen.83612*

> review of the literature. Building and Environment. 2016;**105**:369-389

[40] Kolokotsa D, Santamouris M. Review of the indoor environmental quality and energy consumption studies for low income households in Europe. Science of the Total Environment.

[41] Sarbu I, Sebarchievici C. Aspects of indoor environmental quality assessment in buildings. Energy and

[42] Heinzerling D, Schiavon S, Webster T, Arens E. Indoor environmental quality assessment models: A literature review and a proposed weighting and classification scheme. Building and Environment. 2013;**70**:210-222

[43] Reynolds SJ, Black DW, Borin SS, Breuer G, Burmeister LF, Fuortes LJ, et al. Indoor environmental quality in six commercial office buildings in the Midwest United States. Applied Occupational and Environmental Hygiene. 2010;**16**(11):1065-1077

[44] Kang S, Ou D, Mak CM. The impact of indoor environmental quality on work productivity in university openplan research offices. Building and Environment. 2017;**124**:78-89

[45] Geng Y, Ji W, Lin B, Zhu Y. The impact of thermal environment on occupant IEQ perception and productivity. Building and Environment. 2017;**121**:158-167

[46] Kim J, Kong M, Hong T, Jeong K, Lee M. Physiological response of building occupants based on their activity and the indoor environmental quality condition changes. Building and

Environment. 2018;**145**:96-103

[47] Haapakangas A, Hallman DM, Mathiassen SE, Jahncke H. Self-rated productivity and employee wellbeing in activity-based offices: The

Buildings. 2013;**60**:410-419

2015;**536**:316-330

field exposures in kindergarten children. Journal of Exposure Science & Environmental Epidemiology.

[32] WHO. Guidelines for Drinking-Water quality: First Addendum to Third Edition, Vol 1—Recommendations. Geneva, Switzerland: World Health

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[34] Yu CWF, Jeong TK. Building environmental assessment schemes for rating of IAQ in sustainable buildings. Indoor and Built Environment.

[35] Kim J, de Dear R, Cândido C, Zhang H, Arens E. Gender differences in office occupant perception of indoor environmental quality (IEQ ). Building and Environment. 2013;**70**:245-256

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Review of parameters and assessment models. Architectural Science Review.

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[39] Al Horr Y, Arif M, Kaushik A, Mazroei A, Katafygiotou M, Elsarrag E. Occupant productivity and office indoor environment quality: A

2017;**27**(5):497-504

Organization; 2006

2011;**20**(1):5-15

2014;**57**(2):147-154

2015;**40**(2):21

2015;**17**:61-68

[31] Bhatt CR, Redmayne M, Billah B, Abramson MJ, Benke G. Radiofrequency-electromagnetic *Introductory Chapter: Indoor Environmental Quality DOI: http://dx.doi.org/10.5772/intechopen.83612*

field exposures in kindergarten children. Journal of Exposure Science & Environmental Epidemiology. 2017;**27**(5):497-504

*Indoor Environmental Quality*

2016;**66**:852-860

2017;**271**(012029):1-8

pp. 1-12, 2018

A review study. Renewable and Sustainable Energy Reviews.

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[25] Ushada M, Suyantohadi A,

Khuriyati N, Okayama T. Identification of environmental ergonomics control system for Indonesian SMEs. In: 3rd International Conference on Control, Automation and Robotics; 24-26 April 2017; Nagoya, Japan. 2017. pp. 453-456

[26] Fayed I, Bedda M. Electromagnetic radiation and its effects on human beings: Survey and environmental recommendations. In: 15th Scientific Symposium for Hajj, Umrah and Madinah visit—Scientific Portal for 1436AH; 27-28 May 2015; Saudi Arabia.

[27] Valberg PA, van Deventer TE, Repacholi MH. Workgroup report: Base stations and wireless networks- -radiofrequency (RF) exposures and health consequences. Environmental Health Perspectives. 2007;**115**(3):416

[28] Linet MS, Hatch EE, Kleinerman RA, Robison LL, Kaune WT, Friedman DR, et al. Residential exposure to magnetic fields and acute lymphoblastic leukemia in children. The New England Journal of Medicine. 1997;**337**(1):1-8

[29] Kheifets L, Repacholi M, Saunders R, Van Deventer E. The sensitivity of children to electromagnetic fields.

[30] Verloock L, Joseph W, Vermeeren G, Martens L. Procedure for assessment

of general public exposure from WLAN in offices and in wireless sensor network testbed. Health Physics.

[31] Bhatt CR, Redmayne M, Billah B, Abramson MJ, Benke G. Radiofrequency-electromagnetic

2010;**98**(4):628-638

Pediatrics. 2005;**116**:303-313

2018. pp. 1125-1134

2015. pp. 35-47

[17] Tong Y, Abu Bakar H, Sari KM, Ewon U, Labeni M, Fauzan N. Effect of urban noise to the acoustical performance of the secondary school's learning spaces—A case study in Batu Pahat. IOP Conference Series: Materials Science and Engineering.

[18] Jeong K , Hong T, Kim SH, Kim J, Lee S. "Acoustic design of a classical concert hall and evaluation of its acoustic performance—A case study," Preprint, vol.<PHONE_NUMBER>, no. May,

[19] Tan Y, Fang Y, Zhou T, Wang Q, Cheng JCP, Kong H. Improve indoor acoustics performance by using building information modeling. In: 34th International Symposium on Automation and Robotics in Construction (ISARC 2017); 28 June-1

July 2017; Taipei, Taiwan. 2017

Acoustics. 2018;**25**(1):35-42

2018; Munich, Germany. 2018

[20] Lam A, Hodgson M, Prodi N, Visentin C. Effects of classroom acoustics on speech intelligibility and response time: A comparison between native and non-native listeners. Building

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transmission for coupled rooms in virtual reality. In: 44th Annual Conference on Acoustics (DAGA 2018); 19-22 March

[22] Van Renterghem T. Improving the noise reduction by green roofs due to solar panels and substrate shaping. Building Acoustics. 2018;**25**(3):219-232

[23] Edmonds J. Overview of human factors engineering. In: Human Factors in the Chemical and Process Industries. Amsterdam, Netherlands: Elsevier B.V.,

Elsevier Inc.; 2016. pp. 153-167

**10**

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[33] Bluyssen PM, Janssen S, van den Brink LH, de Kluizenaar Y. Assessment of wellbeing in an indoor office environment. Building and Environment. 2011;**46**(12):2632-2640

[34] Yu CWF, Jeong TK. Building environmental assessment schemes for rating of IAQ in sustainable buildings. Indoor and Built Environment. 2011;**20**(1):5-15

[35] Kim J, de Dear R, Cândido C, Zhang H, Arens E. Gender differences in office occupant perception of indoor environmental quality (IEQ ). Building and Environment. 2013;**70**:245-256

[36] Sakhare VV, Ralegaonkar RV. Indoor environmental quality: Review of parameters and assessment models. Architectural Science Review. 2014;**57**(2):147-154

[37] Rashid M. A review of the empirical literature on the relationships between indoor environment and stress in health care and office settings— Problems and prospects of sharing evidence. Environment and Behavior. 2015;**40**(2):21

[38] Nimlyat PS, Kandar MZ. Appraisal of indoor environmental quality (IEQ ) in healthcare facilities: A literature review. Sustainable Cities and Society. 2015;**17**:61-68

[39] Al Horr Y, Arif M, Kaushik A, Mazroei A, Katafygiotou M, Elsarrag E. Occupant productivity and office indoor environment quality: A

review of the literature. Building and Environment. 2016;**105**:369-389

[40] Kolokotsa D, Santamouris M. Review of the indoor environmental quality and energy consumption studies for low income households in Europe. Science of the Total Environment. 2015;**536**:316-330

[41] Sarbu I, Sebarchievici C. Aspects of indoor environmental quality assessment in buildings. Energy and Buildings. 2013;**60**:410-419

[42] Heinzerling D, Schiavon S, Webster T, Arens E. Indoor environmental quality assessment models: A literature review and a proposed weighting and classification scheme. Building and Environment. 2013;**70**:210-222

[43] Reynolds SJ, Black DW, Borin SS, Breuer G, Burmeister LF, Fuortes LJ, et al. Indoor environmental quality in six commercial office buildings in the Midwest United States. Applied Occupational and Environmental Hygiene. 2010;**16**(11):1065-1077

[44] Kang S, Ou D, Mak CM. The impact of indoor environmental quality on work productivity in university openplan research offices. Building and Environment. 2017;**124**:78-89

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Procedia Engineering. 2017;**190**:496-503

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[61] Nasir ARM, Musa AR, Che-Ani AI, Utaberta N, Abdullah NAG, Tawil NM. Identification of indoor environmental quality (IEQ ) parameter

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in creating conducive learning environment for architecture studio. Procedia Engineering. 2011;**20**:354-362

2012;**56**:335-345

2014;**81**:127-140

environmental quality in assisted living facilities. Journal of Interior Design.

[49] Ali AS, Chua SJL, Lim MEL. The effect of physical environment comfort on employees' performance in office buildings: A case study of three public universities in Malaysia. Structural Survey. 2015;**33**(4-5):294-308

[50] Huang L, Zhu Y, Ouyang Q, Cao B. A study on the effects of thermal, luminous, and acoustic environments on indoor environmental comfort in offices. Building and Environment.

[51] Frontczak M, Schiavon S, Goins J, Arens E, Zhang H, Wargocki P. Quantitative relationships between occupant satisfaction and satisfaction aspects of indoor environmental quality and building design. Indoor Air.

[52] Wong LT, Mui KW, Hui PS. A multivariate-logistic model for acceptance of indoor environmental quality (IEQ ) in offices. Building and

Environment. 2008;**43**(1):1-6

of productivity loss in air-

2004;**36**(10):987-993

2004;**36**(10):981-986

[53] Kosonen R, Tan F. Assessment

conditioned buildings using PMV index. Energy and Buildings.

[54] Kosonen R, Tan F. The effect of perceived indoor air quality on productivity loss. Energy and Buildings.

[55] Almeida RMSF, De Freitas VP. Indoor environmental quality of classrooms in Southern European

**12**

[64] Garcia F, Shendell DG, Madrigano J. Relationship among environmental quality variables, housing variables, and residential needs: A secondary analysis of the relationship among indoor, outdoor, and personal air (RIOPA) concentrations database. International Journal of Biometeorology. 2017;**61**(3):513-525

[65] Andrade C, Lima ML, Fornara F, Bonaiuto M. Users' views of hospital environmental quality: Validation of the perceived hospital environment quality indicators (PHEQIs). Journal of Environmental Psychology. 2012;**32**(2):97-111

[66] De Giuli V, Zecchin R, Salmaso L, Corain L, De Carli M. Measured and perceived indoor environmental quality: Padua Hospital case study. Building and Environment. 2013;**59**:211-226

[67] Choi S. The relationships among indoor environmental quality, occupant satisfaction, work performance, and sustainability ethic in sustainable buildings [PhD thesis]. The University of Minnesota; 2011

[68] Hwang T, Kim JT. Assessment of indoor environmental quality in open-plan offices. Indoor and Built Environment. 2013;**22**(1):139-156

[69] Ravindu S, Rameezdeen R, Zuo J, Zhou Z, Chandratilake R. Indoor environment quality of green buildings: Case study of an LEED platinum certified factory in a warm humid tropical climate. Building and Environment. 2015;**84**:105-113

**15**

**Chapter 2**

**Abstract**

*Joseph Laquatra*

places where people live.

**1. Introduction**

Indoor Air Quality

Indoor air pollution is an international health concern because people spend a majority of their time indoors. Children are at a higher risk of health problems from pollutant exposure, especially because air in the child breathing zone is more polluted than it is in the adult breathing zone. Pollutants of concern include biological contaminants, combustion pollutants, volatile organic compounds, and radon and other soil gases. Humans have a history with lead and asbestos that goes back thousands of years to the ancient Romans and Egyptians. These two pollutants are still problems in older homes and apartments. All of these toxicants can be minimized or abated. Awareness of these issues is a critical first step in improving air quality in

**Keywords:** biological contaminants, combustion pollutants, volatile organic

In recent years, indoor air pollution has become an international health concern. Research has shown that people spend about 90% of their time indoors [1] and 75% of their time indoors in their homes [2]. Some people such as children, the elderly, and infirm spend most or all of their time indoors [3, 4]. Research also indicates that pollutant levels can be higher indoors than outdoors [5]. Concerns about indoor air quality have led to indoor air management becoming a new consumer skill. Steps involved in indoor air management include identifying a pollutant of concern, controlling it at its source, and if that fails, mitigation. Residential indoor air pollutants include biological contaminants, volatile organic compounds, radon and other soil

Biological contaminants include mold, viruses, bacteria, pollen, animal dander, and dust mites. Moisture plays an essential role in the presence of biological contaminants. As shown in **Figure 1**, warm air holds more water vapor than cold air. The cube on the left represents a volume of air that is at 75°F, with 30% relative humidity. This means that it is holding 30% of the moisture that it is *capable* of holding. When that same amount of air cools to 40°F, it contains the *same amount* of water, but it is now at 100% relative humidity. In other words, it is holding all of the moisture that it *can* hold. Moisture will condense at 100% relative humidity. This is

compounds, radon, lead, asbestos, child breathing zone

gases, combustion pollutants, lead, and asbestos.

also called the saturation point or the dew point temperature.

**2. Biological contaminants**

## **Chapter 2** Indoor Air Quality

*Joseph Laquatra*

### **Abstract**

Indoor air pollution is an international health concern because people spend a majority of their time indoors. Children are at a higher risk of health problems from pollutant exposure, especially because air in the child breathing zone is more polluted than it is in the adult breathing zone. Pollutants of concern include biological contaminants, combustion pollutants, volatile organic compounds, and radon and other soil gases. Humans have a history with lead and asbestos that goes back thousands of years to the ancient Romans and Egyptians. These two pollutants are still problems in older homes and apartments. All of these toxicants can be minimized or abated. Awareness of these issues is a critical first step in improving air quality in places where people live.

**Keywords:** biological contaminants, combustion pollutants, volatile organic compounds, radon, lead, asbestos, child breathing zone

### **1. Introduction**

In recent years, indoor air pollution has become an international health concern. Research has shown that people spend about 90% of their time indoors [1] and 75% of their time indoors in their homes [2]. Some people such as children, the elderly, and infirm spend most or all of their time indoors [3, 4]. Research also indicates that pollutant levels can be higher indoors than outdoors [5]. Concerns about indoor air quality have led to indoor air management becoming a new consumer skill. Steps involved in indoor air management include identifying a pollutant of concern, controlling it at its source, and if that fails, mitigation. Residential indoor air pollutants include biological contaminants, volatile organic compounds, radon and other soil gases, combustion pollutants, lead, and asbestos.

### **2. Biological contaminants**

Biological contaminants include mold, viruses, bacteria, pollen, animal dander, and dust mites. Moisture plays an essential role in the presence of biological contaminants. As shown in **Figure 1**, warm air holds more water vapor than cold air. The cube on the left represents a volume of air that is at 75°F, with 30% relative humidity. This means that it is holding 30% of the moisture that it is *capable* of holding. When that same amount of air cools to 40°F, it contains the *same amount* of water, but it is now at 100% relative humidity. In other words, it is holding all of the moisture that it *can* hold. Moisture will condense at 100% relative humidity. This is also called the saturation point or the dew point temperature.

#### **Figure 1.** *Warm air holds more moisture than cold air.*

When warm, moist air comes in contact with a cold surface, the water vapor in that air condenses to liquid water. In the case of a cold window, when warmer, humid air moves closer to the window, its temperature drops, and therefore its moisture-holding capability also drops. When this air touches the window, it condenses. The same thing happens on a warm and humid summer day, when warm, humid air condenses on cold beverage bottles, cans, or glasses. Sometimes, condensation on a window can be a nuisance. Other times, it can be serious enough that moisture will accumulate on the sash and on the sill, causing mold growth, warping that will damage the airtight seal between panes of glass, and even rotting. Mold spores are ubiquitous, and when a spore lands on a surface at the right temperature, with a food source—in this case, cellulose—and moisture, mold will grow.

Mold is a fungus; and as fungi grow, they release large numbers of spores into the air. And as mold digests cellulosic products, such as wood, as food, it releases carbon dioxide, water, and microbiological volatile organic compounds (mVOCs) into the air. Airborne spores affect asthmatics and people with allergies by acting as asthma triggers and the cause of respiratory illness. Microbiological volatile organic compounds are responsible for the musty smell associated with mold growth.

Preventing health problems caused by exposure to mold is done by controlling moisture in homes. This means maintaining relative humidity at levels that do not allow for moisture condensation on windows and other surfaces, regularly inspecting plumbing pipes and fixtures for leaks, and preventing the entry of water from outside the home by maintaining roofs and siding and having a water-managed foundation.

Another biological contaminant commonly found in homes is the house dust mite, which feeds on skin cells that are naturally shed from human bodies. Fecal pellets from this microscopic arachnid contain a protein that is an allergen and asthma trigger. Dust mites thrive in humid environments and live in upholstered furniture, bedding, carpeting, and stuffed animals. They cannot survive at relative humidity levels below 50% [6]. Other biological contaminants in indoor air include viruses, bacteria, pollen, and animal dander. All of these can be controlled through regular house cleaning.

### **2.1 Ventilation**

A number of factors contribute to the high levels of energy efficiency that are now possible in new and existing homes. Airtightening measures—those that

**17**

**Figure 2.** *The stack effect.*

*Indoor Air Quality*

*DOI: http://dx.doi.org/10.5772/intechopen.81192*

moisture and other indoor air pollutants.

pull air out of a house but also provide make-up air.

prevent air infiltration through the building shell—are among the most critical of these. In new construction and in the improvement of an existing home, low air infiltration rates are achieved through an attention to the details of both construction materials and practices. And as air leakage has decreased in homes, ventilation has become a residential design issue because of problems that arise from excess

Before airtightening measures were as widespread as they now are, ventilation of homes was achieved naturally, as air leaked in and out of cracks in the building shell—around windows and doors, where dissimilar building materials meet, and other places. Natural ventilation is undesirable because it can never be controlled. Its rate depends on wind speed, vegetation around a house, site topography, and other variables. And natural ventilation imposes large energy costs on a home because the incoming infiltration air must be heated in the winter in cold climates. But in the absence of natural ventilation, mechanical ventilation is necessary for removing moisture and other pollutants as well as bringing fresh air into a home. A basic mechanical ventilation system consists of exhaust fans, which are ducted

to the outdoors, in kitchens and bathrooms. Conventional clothes dryers should always be ducted to the outdoors, although some electric clothes dryers vent into the washer. And some clothes washers also act as dryers. An issue that arises in airtight homes is the provision of make-up air for exhaust systems. As exhaust fans pull air out of a house, that air must be replaced. In a leaky house, that air is supplied through infiltration. This happens because the fans place negative pressure on a house and, if no windows are open, pull in air from cracks that exist in the building enclosure or from a chimney, which can be dangerous if the chimney is connected to an operating combustion appliance. Other ventilation systems exist that not only

**Figure 2** shows temperature-difference-driven infiltration, also called the stack effect. In simpler terms: a house comes under negative pressure as warm air naturally rises to upper levels of a house. That warm air escapes through various faults in the building enclosure, including cracks that form at junctions of different types of construction materials, such as those where brick meets wood siding. Warm air

#### *Indoor Air Quality DOI: http://dx.doi.org/10.5772/intechopen.81192*

*Indoor Environmental Quality*

**Figure 1.**

*Warm air holds more moisture than cold air.*

When warm, moist air comes in contact with a cold surface, the water vapor in that air condenses to liquid water. In the case of a cold window, when warmer, humid air moves closer to the window, its temperature drops, and therefore its moisture-holding capability also drops. When this air touches the window, it condenses. The same thing happens on a warm and humid summer day, when warm, humid air condenses on cold beverage bottles, cans, or glasses. Sometimes, condensation on a window can be a nuisance. Other times, it can be serious enough that moisture will accumulate on the sash and on the sill, causing mold growth, warping that will damage the airtight seal between panes of glass, and even rotting.

Mold is a fungus; and as fungi grow, they release large numbers of spores into the air. And as mold digests cellulosic products, such as wood, as food, it releases carbon dioxide, water, and microbiological volatile organic compounds (mVOCs) into the air. Airborne spores affect asthmatics and people with allergies by acting as asthma triggers and the cause of respiratory illness. Microbiological volatile organic compounds are responsible for the musty smell associated with mold growth. Inhalation of mVOCs by humans can cause mycotoxicosis, symptoms of which

Preventing health problems caused by exposure to mold is done by controlling moisture in homes. This means maintaining relative humidity at levels that do not allow for moisture condensation on windows and other surfaces, regularly inspecting plumbing pipes and fixtures for leaks, and preventing the entry of water from outside the home by maintaining roofs and siding and having a water-managed foundation. Another biological contaminant commonly found in homes is the house dust mite, which feeds on skin cells that are naturally shed from human bodies. Fecal pellets from this microscopic arachnid contain a protein that is an allergen and asthma trigger. Dust mites thrive in humid environments and live in upholstered furniture, bedding, carpeting, and stuffed animals. They cannot survive at relative humidity levels below 50% [6]. Other biological contaminants in indoor air include viruses, bacteria, pollen, and animal dander. All of these can be controlled through regular house cleaning.

A number of factors contribute to the high levels of energy efficiency that are now possible in new and existing homes. Airtightening measures—those that

**16**

**2.1 Ventilation**

prevent air infiltration through the building shell—are among the most critical of these. In new construction and in the improvement of an existing home, low air infiltration rates are achieved through an attention to the details of both construction materials and practices. And as air leakage has decreased in homes, ventilation has become a residential design issue because of problems that arise from excess moisture and other indoor air pollutants.

Before airtightening measures were as widespread as they now are, ventilation of homes was achieved naturally, as air leaked in and out of cracks in the building shell—around windows and doors, where dissimilar building materials meet, and other places. Natural ventilation is undesirable because it can never be controlled. Its rate depends on wind speed, vegetation around a house, site topography, and other variables. And natural ventilation imposes large energy costs on a home because the incoming infiltration air must be heated in the winter in cold climates. But in the absence of natural ventilation, mechanical ventilation is necessary for removing moisture and other pollutants as well as bringing fresh air into a home.

A basic mechanical ventilation system consists of exhaust fans, which are ducted to the outdoors, in kitchens and bathrooms. Conventional clothes dryers should always be ducted to the outdoors, although some electric clothes dryers vent into the washer. And some clothes washers also act as dryers. An issue that arises in airtight homes is the provision of make-up air for exhaust systems. As exhaust fans pull air out of a house, that air must be replaced. In a leaky house, that air is supplied through infiltration. This happens because the fans place negative pressure on a house and, if no windows are open, pull in air from cracks that exist in the building enclosure or from a chimney, which can be dangerous if the chimney is connected to an operating combustion appliance. Other ventilation systems exist that not only pull air out of a house but also provide make-up air.

**Figure 2** shows temperature-difference-driven infiltration, also called the stack effect. In simpler terms: a house comes under negative pressure as warm air naturally rises to upper levels of a house. That warm air escapes through various faults in the building enclosure, including cracks that form at junctions of different types of construction materials, such as those where brick meets wood siding. Warm air

**Figure 2.** *The stack effect.*

#### *Indoor Environmental Quality*

also escapes from unsealed cracks around windows and doors. All air that leaves a house in this manner must be replenished. This happens when air leaving the house creates suction pressure on lower house levels, which causes soil gases, including radon, to be pulled into the house.

**Figure 3** shows how combustion appliances can also bring a house under negative pressure. All combustion appliances use some type of fuel, whether it is fuel oil, natural gas, propane, or wood. Oxygen is needed to fuel the fire, and if that oxygen comes from indoor air, it will put negative pressure on a house, just like the stack effect does. Air gets drawn into the appliance, fuels the fire, and that air needs to be replaced. The replaced air comes in through cracks in the building enclosure as well as cracks in the foundation of the basement, which can allow soil gases to enter the home.

A solution to negative pressure caused by a combustion appliance is to use a sealed combustion appliance. This type of furnace or boiler brings air to the combustion chamber through a pipe that originates outside the house. Sealed systems typically have a second heat exchanger that extracts heat from combustion gases that would normally be exhausted by the chimney in a conventional system. Instead, extracting additional heat from combustion gases results in exhaust gases that are cool enough to be exhausted from the house through a pipe through an exterior wall, much like a clothes dryer vent. Because the combustion air comes from outside the house, the building does not come under negative pressure.

Approaches to residential ventilation can be categorized as exhaust, supply, and balanced systems. Fans that pull air out of a space such as a bathroom exhaust fan or a kitchen range ventilation hood comprise basic exhaust ventilation systems that most people are familiar with. As noted above, however, these fans can place an airtight house under negative pressure.

Variations of exhaust systems provide make-up air to the house in some manner. The simplest way to do this is to install passive vents, which are small, screened openings in exterior walls. These admit air by opening when the home comes under negative pressure, such as when an exhaust fan is turned on. Passive vents are only recommended for use in very small, airtight homes in which depressurization is safe. Home depressurization is safe if all combustion appliances receive combustion air from outside the home; there are no fireplaces in the home; the home has no attached garage; and the home is not located in a high radon area.

More commonly used than exhaust fans with passive vents is a central exhaust system that pulls air out of a house combined with a fan that pulls fresh air into the house and delivers it through ducts to individual rooms, usually each bedroom

**19**

*Indoor Air Quality*

delivered to the rooms.

*Heat recovery ventilator.*

**Figure 4.**

problems.

**3. Volatile organic compounds**

*DOI: http://dx.doi.org/10.5772/intechopen.81192*

and living area. Whole-house fans are effective in this type of supply system. A variation of this system, if the house has a forced air furnace, is to deliver outdoor air to the return duct, so that it can be mixed with indoor air and heated before it is

A heat recovery ventilator (HRV)—also referred to as an air-to-air heat exchanger—is a balanced system that consists of a device which pulls fresh air into a home at the same time that it is exhausting air out of the home. As seen in **Figure 4**, the two airstreams are separated but pass over a core of conductive plates or heat exchanger that transfers heat from the warmer airstream to the colder one. A heat recovery ventilator also dehumidifies the home, because the warmer airstream contains moisture that condenses during the exchange process. The resulting water is delivered to a drain through a tube. HRVs can be stand-alone units with ducts or they can be integrated with the ducts of a forced air furnace. In addition to the basic systems described above, other variations exist, including central exhaust/supply systems with dehumidification and systems with air filtration options. Several studies have analyzed the cost effectiveness of various ventilation systems by examining purchase and installation costs, annual operating costs, and additional imposed heating costs (to heat incoming air). In addition to costs, benefits that are difficult to quantify include increased human comfort and the prevention of moisture

Taylor et al. [7] examined the cost-effectiveness of heat recovery ventilators and concluded that these units provide positive life-cycle cost savings throughout much

The International Residential Code (IRC) specifies mechanical ventilation standards for new homes, which vary depending on the size of the house, number of bedrooms, and tested air infiltration rate [8]. The infiltration rate is measured with a blower door test, a specialized piece of equipment that measures a home's air change per hour (ACH). ACH measures the extent to which outdoor air leaks into homes through cracks around windows, doors, and where dissimilar building materials meet. An airtight home has a low ACH; a leaky, drafty home has a high ACH.

Volatile organic compounds (VOCs) are gases released from some solids or liquids at room temperature. Many VOCs found in household air have adverse health impacts, including eye, nose, and throat irritation; asthma exacerbation; lung, kidney, and central nervous system damage; and cancer [9]. VOC sources include building products, paints, strippers, solvents, wood preservatives, air fresheners,

of the United States, although not in the colder, northern tier states.

hobby supplies, pesticides, dry-cleaned clothing, and more.

**Figure 3.** *Combustion air concepts.*

**Figure 4.** *Heat recovery ventilator.*

*Indoor Environmental Quality*

radon, to be pulled into the house.

also escapes from unsealed cracks around windows and doors. All air that leaves a house in this manner must be replenished. This happens when air leaving the house creates suction pressure on lower house levels, which causes soil gases, including

foundation of the basement, which can allow soil gases to enter the home.

house, the building does not come under negative pressure.

airtight house under negative pressure.

A solution to negative pressure caused by a combustion appliance is to use a sealed combustion appliance. This type of furnace or boiler brings air to the combustion chamber through a pipe that originates outside the house. Sealed systems typically have a second heat exchanger that extracts heat from combustion gases that would normally be exhausted by the chimney in a conventional system. Instead, extracting additional heat from combustion gases results in exhaust gases that are cool enough to be exhausted from the house through a pipe through an exterior wall, much like a clothes dryer vent. Because the combustion air comes from outside the

Approaches to residential ventilation can be categorized as exhaust, supply, and balanced systems. Fans that pull air out of a space such as a bathroom exhaust fan or a kitchen range ventilation hood comprise basic exhaust ventilation systems that most people are familiar with. As noted above, however, these fans can place an

Variations of exhaust systems provide make-up air to the house in some manner.

More commonly used than exhaust fans with passive vents is a central exhaust system that pulls air out of a house combined with a fan that pulls fresh air into the house and delivers it through ducts to individual rooms, usually each bedroom

The simplest way to do this is to install passive vents, which are small, screened openings in exterior walls. These admit air by opening when the home comes under negative pressure, such as when an exhaust fan is turned on. Passive vents are only recommended for use in very small, airtight homes in which depressurization is safe. Home depressurization is safe if all combustion appliances receive combustion air from outside the home; there are no fireplaces in the home; the home has no

attached garage; and the home is not located in a high radon area.

**Figure 3** shows how combustion appliances can also bring a house under negative pressure. All combustion appliances use some type of fuel, whether it is fuel oil, natural gas, propane, or wood. Oxygen is needed to fuel the fire, and if that oxygen comes from indoor air, it will put negative pressure on a house, just like the stack effect does. Air gets drawn into the appliance, fuels the fire, and that air needs to be replaced. The replaced air comes in through cracks in the building enclosure as well as cracks in the

**18**

**Figure 3.**

*Combustion air concepts.*

and living area. Whole-house fans are effective in this type of supply system. A variation of this system, if the house has a forced air furnace, is to deliver outdoor air to the return duct, so that it can be mixed with indoor air and heated before it is delivered to the rooms.

A heat recovery ventilator (HRV)—also referred to as an air-to-air heat exchanger—is a balanced system that consists of a device which pulls fresh air into a home at the same time that it is exhausting air out of the home. As seen in **Figure 4**, the two airstreams are separated but pass over a core of conductive plates or heat exchanger that transfers heat from the warmer airstream to the colder one. A heat recovery ventilator also dehumidifies the home, because the warmer airstream contains moisture that condenses during the exchange process. The resulting water is delivered to a drain through a tube. HRVs can be stand-alone units with ducts or they can be integrated with the ducts of a forced air furnace. In addition to the basic systems described above, other variations exist, including central exhaust/supply systems with dehumidification and systems with air filtration options. Several studies have analyzed the cost effectiveness of various ventilation systems by examining purchase and installation costs, annual operating costs, and additional imposed heating costs (to heat incoming air). In addition to costs, benefits that are difficult to quantify include increased human comfort and the prevention of moisture problems.

Taylor et al. [7] examined the cost-effectiveness of heat recovery ventilators and concluded that these units provide positive life-cycle cost savings throughout much of the United States, although not in the colder, northern tier states.

The International Residential Code (IRC) specifies mechanical ventilation standards for new homes, which vary depending on the size of the house, number of bedrooms, and tested air infiltration rate [8]. The infiltration rate is measured with a blower door test, a specialized piece of equipment that measures a home's air change per hour (ACH). ACH measures the extent to which outdoor air leaks into homes through cracks around windows, doors, and where dissimilar building materials meet. An airtight home has a low ACH; a leaky, drafty home has a high ACH.

### **3. Volatile organic compounds**

Volatile organic compounds (VOCs) are gases released from some solids or liquids at room temperature. Many VOCs found in household air have adverse health impacts, including eye, nose, and throat irritation; asthma exacerbation; lung, kidney, and central nervous system damage; and cancer [9]. VOC sources include building products, paints, strippers, solvents, wood preservatives, air fresheners, hobby supplies, pesticides, dry-cleaned clothing, and more.

The World Health Organization (WHO) categorizes VOCs by the ease with which they are emitted from materials and uses the terms very volatile organic compounds (VVOC), volatile organic compounds (VOCs), and semivolatile organic compounds (SVOCs) [10]. As mentioned earlier, VOCs produced by mold are referred to as microbiologic volatile organic compounds (mVOCs). But all of these fall into the broad category of VOCs.

Formaldehyde, a colorless, strong-smelling gas, is a common VOC used in the production of building materials, cabinets, furnishings, household cleaners, paints, landscape materials, and other products. It is used in the production of plywood, particle board, and medium density fiberboard. Formaldehyde is released into the air in a process referred to as off-gassing. Formaldehyde is also a component of cigarette smoke and a combustion product of wood, kerosene, natural gas, oil, and gasoline.

Adverse health effects from formaldehyde exposure include eye, nose, and throat irritation; wheezing and coughing; and allergic reactions. Long-term exposure to high levels of formaldehyde can cause cancer in humans.

Other VOCs of concern in indoor air include benzene, styrene, xylene, and methylene chloride. Benzene is a human carcinogen that is present in environmental tobacco smoke, solvents, plywood, particle board, fiberglass, wood paneling, adhesives, paint, caulking, and wood strippers. Styrene is used in the manufacturing of plastics, rubber, food containers, carpet backing, vinyl flooring, and resins. Acute health effects from styrene exposure include mucous membrane irritation; depression; muscle weakness; and eye, nose, and throat irritation. Chronic effects include hearing loss, peripheral neuropathy, and kidney damage. Xylene is a solvent and is a component of rubber and adhesives. Health effects from exposure include depression of the central nervous system, dizziness, irritability, and vomiting. Methylene chloride, which is also known as dichloromethane, is used in paint, paint strippers, and adhesives. Exposure can cause damage to the central nervous system, liver cancer, and lung cancer. This is not an exhaustive list of VOCs found in homes but is meant to illustrate potential hazards from common materials.

#### **3.1 VOCs and safety**

When using any product that contains VOCs, provide adequate ventilation to the work area, meet or exceed any label precautions, buy in quantities that will be consumed quickly, and dispose of containers safely. Do not allow children or pets to become exposed to these products. Low-VOC- and No-VOC-containing products are becoming widely available. When possible, use these products instead of conventional alternatives.

### **4. Radon**

Radon is a radioactive gas that has no odor, taste, or color. It is produced during the decay of uranium, has a half-life of 3.8 days, and emits alpha and gamma radiation [11]. Uranium exists in soils all over the world. The radioactive decay process causes uranium to decay to uranium. Uranium and radium are solid elements. But radium decays to a gas: radon. Radon moves easily through permeable soils, such as gravelly and sandy soils, than it does through impermeable soils, such as clay [12]. Cracks in a house foundation and other openings, such as those around pipes that penetrate a house foundation, serve as radon pathways into the house. Radon continues in the decay process once it is inside a home. Radon's decay products are lead, polonium, and bismuth. These decay products become attached to microscopic particulates in house air, which are inhaled by people in the house and lead to lung cancer.

**21**

**Figure 5.**

*Radon entering a home.*

*Indoor Air Quality*

used instead.

*DOI: http://dx.doi.org/10.5772/intechopen.81192*

a better result of a home's radon level.

The process through which radon enters a home is displayed in **Figure 5**. Radon is the second-leading cause of lung cancer after cigarette smoking; radon exposure is responsible for 21,000 deaths per year in the USA [13]. Between one and seven percent of lung cancer fatalities in the USA have been attributed to radon exposure [13]. Radon's presence can be confirmed through the use of short- or long-term radon detectors. A short-term detector consists of activated carbon, which adsorbs (collects on the surface of carbon granules) radon, is inexpensive and simple to use. Once activated, it is placed in the lowest room of the house and kept in place for three days. The house should be tested under closed house conditions. This means all windows are closed for the duration of the test, and doors are used only for normal entrances and exits. After the test period, the detector is sent to a laboratory for analysis. The laboratory then reports the test results to the sender. Radon levels in a house vary over time because of changes in weather and atmospheric pressure. So, a short-term test is effectively a snapshot of radon levels at a particular time. A long-term radon test uses what is known as an alpha track detector. This is placed in a home's living room and stays there for 90 days to a year. This type of test provides

The U. S. Environmental Protection Agency (EPA) recommends that mitigation systems be installed at or above the Action Level of 4 picocuries per liter (pCi/L) of air [14]. A mitigation system for an existing home consists of a PVC pipe that is installed through the floor of the lowest level of a home, often a basement, into a layer of gravel. That pipe is carried up through the house attic and through the roof. This pipe can also be installed on a house exterior wall. Often, an inline exhaust fan is connected to the PVC pipe and is used to pull soil gas from below the house. When that fan is used, the mitigation system is referred to as an active system. An inline fan is not always necessary and a passive mitigation system is

The EPA has developed a U.S. map that designates counties into zones. In EPA-designated Zone 1 counties, indoor radon levels are expected to be 4 pCi/L or higher; houses in Zone 2 counties are expected to have radon levels between 2 and 4 pCi/L; homes in Zone 3 counties are expected to have radon levels below 2 pCi/L.

#### *Indoor Air Quality DOI: http://dx.doi.org/10.5772/intechopen.81192*

*Indoor Environmental Quality*

**3.1 VOCs and safety**

conventional alternatives.

**4. Radon**

fall into the broad category of VOCs.

The World Health Organization (WHO) categorizes VOCs by the ease with which they are emitted from materials and uses the terms very volatile organic compounds (VVOC), volatile organic compounds (VOCs), and semivolatile organic compounds (SVOCs) [10]. As mentioned earlier, VOCs produced by mold are referred to as microbiologic volatile organic compounds (mVOCs). But all of these

Formaldehyde, a colorless, strong-smelling gas, is a common VOC used in the production of building materials, cabinets, furnishings, household cleaners, paints, landscape materials, and other products. It is used in the production of plywood, particle board, and medium density fiberboard. Formaldehyde is released into the air in a process referred to as off-gassing. Formaldehyde is also a component of cigarette smoke and a combustion product of wood, kerosene, natural gas, oil, and gasoline. Adverse health effects from formaldehyde exposure include eye, nose, and throat irritation; wheezing and coughing; and allergic reactions. Long-term expo-

Other VOCs of concern in indoor air include benzene, styrene, xylene, and methylene chloride. Benzene is a human carcinogen that is present in environmental tobacco smoke, solvents, plywood, particle board, fiberglass, wood paneling, adhesives, paint, caulking, and wood strippers. Styrene is used in the manufacturing of plastics, rubber, food containers, carpet backing, vinyl flooring, and resins. Acute health effects from styrene exposure include mucous membrane irritation; depression; muscle weakness; and eye, nose, and throat irritation. Chronic effects include hearing loss, peripheral neuropathy, and kidney damage. Xylene is a solvent and is a component of rubber and adhesives. Health effects from exposure include depression of the central nervous system, dizziness, irritability, and vomiting. Methylene chloride, which is also known as dichloromethane, is used in paint, paint strippers, and adhesives. Exposure can cause damage to the central nervous system, liver cancer, and lung cancer. This is not an exhaustive list of VOCs found in homes

sure to high levels of formaldehyde can cause cancer in humans.

but is meant to illustrate potential hazards from common materials.

air, which are inhaled by people in the house and lead to lung cancer.

When using any product that contains VOCs, provide adequate ventilation to the work area, meet or exceed any label precautions, buy in quantities that will be consumed quickly, and dispose of containers safely. Do not allow children or pets to become exposed to these products. Low-VOC- and No-VOC-containing products are becoming widely available. When possible, use these products instead of

Radon is a radioactive gas that has no odor, taste, or color. It is produced during the decay of uranium, has a half-life of 3.8 days, and emits alpha and gamma radiation [11]. Uranium exists in soils all over the world. The radioactive decay process causes uranium to decay to uranium. Uranium and radium are solid elements. But radium decays to a gas: radon. Radon moves easily through permeable soils, such as gravelly and sandy soils, than it does through impermeable soils, such as clay [12]. Cracks in a house foundation and other openings, such as those around pipes that penetrate a house foundation, serve as radon pathways into the house. Radon continues in the decay process once it is inside a home. Radon's decay products are lead, polonium, and bismuth. These decay products become attached to microscopic particulates in house

**20**

The process through which radon enters a home is displayed in **Figure 5**. Radon is the second-leading cause of lung cancer after cigarette smoking; radon exposure is responsible for 21,000 deaths per year in the USA [13]. Between one and seven percent of lung cancer fatalities in the USA have been attributed to radon exposure [13].

Radon's presence can be confirmed through the use of short- or long-term radon detectors. A short-term detector consists of activated carbon, which adsorbs (collects on the surface of carbon granules) radon, is inexpensive and simple to use. Once activated, it is placed in the lowest room of the house and kept in place for three days. The house should be tested under closed house conditions. This means all windows are closed for the duration of the test, and doors are used only for normal entrances and exits. After the test period, the detector is sent to a laboratory for analysis. The laboratory then reports the test results to the sender. Radon levels in a house vary over time because of changes in weather and atmospheric pressure. So, a short-term test is effectively a snapshot of radon levels at a particular time. A long-term radon test uses what is known as an alpha track detector. This is placed in a home's living room and stays there for 90 days to a year. This type of test provides a better result of a home's radon level.

The U. S. Environmental Protection Agency (EPA) recommends that mitigation systems be installed at or above the Action Level of 4 picocuries per liter (pCi/L) of air [14]. A mitigation system for an existing home consists of a PVC pipe that is installed through the floor of the lowest level of a home, often a basement, into a layer of gravel. That pipe is carried up through the house attic and through the roof. This pipe can also be installed on a house exterior wall. Often, an inline exhaust fan is connected to the PVC pipe and is used to pull soil gas from below the house. When that fan is used, the mitigation system is referred to as an active system. An inline fan is not always necessary and a passive mitigation system is used instead.

The EPA has developed a U.S. map that designates counties into zones. In EPA-designated Zone 1 counties, indoor radon levels are expected to be 4 pCi/L or higher; houses in Zone 2 counties are expected to have radon levels between 2 and 4 pCi/L; homes in Zone 3 counties are expected to have radon levels below 2 pCi/L.

**Figure 5.** *Radon entering a home.*

**Figure 6.** *EPA Radon Zone Map.*

**Figure 6** shows the EPA Radon Map. Zone 1 counties are red; Zone 2 counties are orange; and Zone 3 counties are yellow.

Radon-resistant construction techniques are recommended for new homes built in Zone 1 counties [15].

### **5. Combustion products**

Combustion products comprise another category of indoor air pollutants. They consist of nitrogen oxides, sulfur dioxide, carbon monoxide, respirable particulates, and water. Nitrogen oxides, sulfur dioxides, and respirable particulates are lung irritants, and carbon monoxide (CO) can kill. To avoid indoor these pollutants, combustion-based, unvented space heaters should not be in the home. Central heating system systems should be regularly serviced: annual servicing for fuel oil-based systems and every 2 years for gas systems. Smoking should not be permitted in a home, and a gas kitchen range should have an exhaust fan over it that is vented to the outside.

Combustion products can pollute the air inside a home when components of a central heating system are damaged and leak combustion gases into indoor air. Indoor use of combustion-based electric generators will also do this. And when a house comes under negative pressure, combustion gases can be drawn from a chimney or fireplace into the home.

Normally, when a person breathes healthy air, oxygen binds with hemoglobin in blood to form oxyhemoglobin. When a person breathes air that is polluted with CO, CO binds with hemoglobin, and carboxyhemoglobin is formed, which prevents oxygen from getting to the brain. At low levels, this causes tiredness and dizziness. At higher levels, gradual suffocation and death occur. Carbon monoxide is responsible for hundreds of deaths and thousands of emergency room visits in the USA per year [16]. These are all preventable deaths and often occur when people are sleeping. Every home and apartment should have at least one carbon monoxide

**23**

issue.

**7. Asbestos**

*Indoor Air Quality*

home.

**6. Lead**

*DOI: http://dx.doi.org/10.5772/intechopen.81192*

the USA with lead-based paint [18].

effects. No level of exposure to lead is safe [19].

planted to discourage children from playing in that soil.

and wallets; and others [21].

ing board covers and potholders.

detector installed in the hallway outside the sleeping area. Carbon monoxide detectors are important, but they are no substitute for regular servicing of combustion appliances and common sense safety procedures with combustion appliances in the

People have used lead for numerous purposes for at least 7000 years [17]. Before 1550 BCE, ancient Egyptians used lead as a medicine and for decorative purposes. When babies were born, a lead ball was placed on their belly buttons to stop bleeding. Women would decorate their nipples with lead and breast feed their babies. People have been aware of lead poisoning for over 2000 years [17]. In spite of this, lead was not banned as an ingredient in residential paint in the USA until 1978 and in gasoline until 1986. There are an estimated 24 million homes and apartments in

Negative health impacts from lead exposure include reduced IQ levels, behavioral problems, organ damage, anemia, convulsions, and death. Children

affected as well. Pregnant women can experience damage to a fetus from lead. Exposure occurs through inhalation, ingestion, and dermatological contact. The U.S. Centers for Disease Control and Prevention (CDC) set 5 micrograms of lead per deciliter (μg/dL) of blood as a reference for public health actions, but there is no minimum level of exposure that is considered to be free of negative health

Lead-painted surfaces can produce a fine dust that is poisonous, especially to infants and children. This dust accumulates on floors under lead-painted windows and other building components. Toddlers crawl through this dust and ingest it through hand-to-mouth contact. This can also occur as children play outside in lead-contaminated soil. These hazards can be reduced or eliminated by following Lead Safe Work Practices to remove or encapsulate lead-based paint on a home's interior and exterior surfaces [20]. For soil contaminated with lead from paint chips or vehicle exhaust, that soil should be replaced, or barriers such as bushes should be

Lead is also present in many household products, including slow cookers; lipstick and other cosmetics; house keys; hair dyes; faux leather purses, sandals,

The term asbestos refers to naturally occurring silicate minerals that are heat-resistant and fibrous. The fibers are soft and can be easily incorporated into building materials. Chrysotile, or white asbestos, was most commonly used in construction materials. Asbestos is found in older homes. It was used as insulation on heating systems and heating ducts. In some older homes, it actually covers entire boilers. Asbestos was also a component of joint compound, sheet goods that were used as fire barriers behind wood-burning stoves, roof sealants, floor and ceiling tile adhesives, gaskets, and automobile brake pads. Asbestos was also used in iron-

Consumer education on this topic is necessary to inform the public about this

face higher risks of health problems from lead exposure, but adults are

detector installed in the hallway outside the sleeping area. Carbon monoxide detectors are important, but they are no substitute for regular servicing of combustion appliances and common sense safety procedures with combustion appliances in the home.

### **6. Lead**

*Indoor Environmental Quality*

orange; and Zone 3 counties are yellow.

in Zone 1 counties [15].

**Figure 6.**

*EPA Radon Zone Map.*

the outside.

**5. Combustion products**

chimney or fireplace into the home.

**Figure 6** shows the EPA Radon Map. Zone 1 counties are red; Zone 2 counties are

Radon-resistant construction techniques are recommended for new homes built

Combustion products comprise another category of indoor air pollutants. They consist of nitrogen oxides, sulfur dioxide, carbon monoxide, respirable particulates, and water. Nitrogen oxides, sulfur dioxides, and respirable particulates are lung irritants, and carbon monoxide (CO) can kill. To avoid indoor these pollutants, combustion-based, unvented space heaters should not be in the home. Central heating system systems should be regularly serviced: annual servicing for fuel oil-based systems and every 2 years for gas systems. Smoking should not be permitted in a home, and a gas kitchen range should have an exhaust fan over it that is vented to

Combustion products can pollute the air inside a home when components of a central heating system are damaged and leak combustion gases into indoor air. Indoor use of combustion-based electric generators will also do this. And when a house comes under negative pressure, combustion gases can be drawn from a

Normally, when a person breathes healthy air, oxygen binds with hemoglobin in blood to form oxyhemoglobin. When a person breathes air that is polluted with CO, CO binds with hemoglobin, and carboxyhemoglobin is formed, which prevents oxygen from getting to the brain. At low levels, this causes tiredness and dizziness. At higher levels, gradual suffocation and death occur. Carbon monoxide is responsible for hundreds of deaths and thousands of emergency room visits in the USA per year [16]. These are all preventable deaths and often occur when people are sleeping. Every home and apartment should have at least one carbon monoxide

**22**

People have used lead for numerous purposes for at least 7000 years [17]. Before 1550 BCE, ancient Egyptians used lead as a medicine and for decorative purposes. When babies were born, a lead ball was placed on their belly buttons to stop bleeding. Women would decorate their nipples with lead and breast feed their babies. People have been aware of lead poisoning for over 2000 years [17]. In spite of this, lead was not banned as an ingredient in residential paint in the USA until 1978 and in gasoline until 1986. There are an estimated 24 million homes and apartments in the USA with lead-based paint [18].

Negative health impacts from lead exposure include reduced IQ levels, behavioral problems, organ damage, anemia, convulsions, and death. Children face higher risks of health problems from lead exposure, but adults are affected as well. Pregnant women can experience damage to a fetus from lead. Exposure occurs through inhalation, ingestion, and dermatological contact. The U.S. Centers for Disease Control and Prevention (CDC) set 5 micrograms of lead per deciliter (μg/dL) of blood as a reference for public health actions, but there is no minimum level of exposure that is considered to be free of negative health effects. No level of exposure to lead is safe [19].

Lead-painted surfaces can produce a fine dust that is poisonous, especially to infants and children. This dust accumulates on floors under lead-painted windows and other building components. Toddlers crawl through this dust and ingest it through hand-to-mouth contact. This can also occur as children play outside in lead-contaminated soil. These hazards can be reduced or eliminated by following Lead Safe Work Practices to remove or encapsulate lead-based paint on a home's interior and exterior surfaces [20]. For soil contaminated with lead from paint chips or vehicle exhaust, that soil should be replaced, or barriers such as bushes should be planted to discourage children from playing in that soil.

Lead is also present in many household products, including slow cookers; lipstick and other cosmetics; house keys; hair dyes; faux leather purses, sandals, and wallets; and others [21].

Consumer education on this topic is necessary to inform the public about this issue.

### **7. Asbestos**

The term asbestos refers to naturally occurring silicate minerals that are heat-resistant and fibrous. The fibers are soft and can be easily incorporated into building materials. Chrysotile, or white asbestos, was most commonly used in construction materials. Asbestos is found in older homes. It was used as insulation on heating systems and heating ducts. In some older homes, it actually covers entire boilers. Asbestos was also a component of joint compound, sheet goods that were used as fire barriers behind wood-burning stoves, roof sealants, floor and ceiling tile adhesives, gaskets, and automobile brake pads. Asbestos was also used in ironing board covers and potholders.

Like lead, humans have used asbestos for thousands of years. In ancient Egypt, pharaohs were embalmed in asbestos cloth. Ancient Roman aristocrats used asbestos tablecloths and napkins. After these items were used, they were placed in fires to clean them. The ancient Roman philosopher, Pliny the Elder, wrote about asbestos-caused lung disease and how asbestos mining slaves suffered from lung disease and made crude respirators to protect themselves [22].

Asbestos exposure occurs when asbestos fibers become friable, or airborne, and are inhaled. These fibers are microscopic and cannot be seen. This makes it possible for someone to inhale a large amount of fibers without knowing it. The fibers become embedded deep within the lungs, and the body cannot expel them. Exposure causes asbestosis, a type of lung cancer, and mesothelioma, which is a cancer of the mesothelial lining of the lungs. These diseases begin to show symptoms 10–40 years after initial exposure to asbestos.

Asbestos abatement is not a do-it-yourself activity. Its removal and encapsulation are regulated in the USA and must be performed by certified abatement contractors. These contractors seal off the work area where asbestos will be removed and wear disposable full-body protective suits and full head protection with respirators.

### **8. The child breathing zone**

Children face higher risks than adults do from being exposed to environmental toxicants and from health problems caused by such exposure [23]. This is because children breathe larger amounts of air per body size when compared to adults. Sucking on hands and toys that have accumulated pollutants adds to these risks [24]. Another source of VOC exposure to infants is those that are emitted from crib mattresses and crib mattress covers [25].

The fact that 80% of children's alveoli are formed postnatally, and changes in the lung continue through adolescence, make children more vulnerable to developing health problems from air pollutants [26]. During the early postneonatal period, developing lungs are very susceptible to pollutants; and the immature immune, pulmonary, and nervous systems of children can be damaged by environmental pollutants, including routinely applied residential pesticides.

Young and older infants and young children breathe through their mouths than adults do. This difference in breathing patterns is likely to increase a child's risk of exposure to respirable particulates [27]. This risk is lower for adults whose breathing through their noses causes air to become filtered as they breathe it through the upper respiratory airway [27].

Toddlers crawl on the floor and young children walk, run, and play on the floor. These factors cause the breathing zone of children to be much lower (up to 3 feet from the floor). This zone is known as the child breathing zone (CBZ) [28]. Walking-induced turbulence in a room causes resuspension of respirable particulates, and shorter people are exposed to more resuspended particulates than taller people. IAQ can be significantly worse in the CBZ than in the adult breathing zone (ABZ), and the assumption of uniform pollutant concentration in indoor environments can be an erroneous assumption of breathing concentration risk. Although there is an increasing awareness that children are vulnerable to poor IAQ in the scientific community, there is very limited research with a focus on IAQ in the CBZ. There is no current IAQ management system that specifically focuses on improving IAQ in the CBZ.

**25**

**Author details**

Joseph Laquatra

*Indoor Air Quality*

**9. Conclusion**

*DOI: http://dx.doi.org/10.5772/intechopen.81192*

The most effective strategy for controlling indoor air pollution is to control the problem at its source. Ventilation is also important, especially in the case of moisture. Expel moisture to the outside through exhaust fans that are vented to the outdoors. In the case of combustion pollutants, regular servicing of heating systems and other appliances that are combustion based is necessary. Radon gas is a radioactive human carcinogen that is colorless, tasteless, and odorless. This pollutant can be controlled through mitigation in existing homes and with radon-resistant construction techniques in new homes. Exposure to some VOCs, which are present in building materials, paints, strippers, and other substances, can be hazardous to human health. Adequate ventilation should be provided when using these materials. Low- or no-VOC emitting products are now available and should be considered as safer alternatives. Lead and asbestos are present in older homes and apartments and pose considerable health risks to humans. Only trained professionals should perform abatement or encapsulation of both materials. Children are at a higher risk of health problems from pollutant exposure, especially because air in the child breathing zone is more polluted than it is in the adult breathing zone. Awareness of these issues is a critical first step in improving air quality in homes and apartments.

provided the original work is properly cited.

Cornell University, Ithaca, New York, USA

\*Address all correspondence to<EMAIL_ADDRESS>
© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

### **9. Conclusion**

*Indoor Environmental Quality*

protect themselves [22].

with respirators.

pesticides.

**8. The child breathing zone**

upper respiratory airway [27].

improving IAQ in the CBZ.

mattresses and crib mattress covers [25].

toms 10–40 years after initial exposure to asbestos.

Like lead, humans have used asbestos for thousands of years. In ancient Egypt, pharaohs were embalmed in asbestos cloth. Ancient Roman aristocrats used asbestos tablecloths and napkins. After these items were used, they were placed in fires to clean them. The ancient Roman philosopher, Pliny the Elder, wrote about asbestos-caused lung disease and how asbestos mining slaves suffered from lung disease and made crude respirators to

Asbestos exposure occurs when asbestos fibers become friable, or airborne, and are inhaled. These fibers are microscopic and cannot be seen. This makes it possible for someone to inhale a large amount of fibers without knowing it. The fibers become embedded deep within the lungs, and the body cannot expel them. Exposure causes asbestosis, a type of lung cancer, and mesothelioma, which is a cancer of the mesothelial lining of the lungs. These diseases begin to show symp-

Asbestos abatement is not a do-it-yourself activity. Its removal and encapsula-

Children face higher risks than adults do from being exposed to environmental toxicants and from health problems caused by such exposure [23]. This is because children breathe larger amounts of air per body size when compared to adults. Sucking on hands and toys that have accumulated pollutants adds to these risks [24]. Another source of VOC exposure to infants is those that are emitted from crib

The fact that 80% of children's alveoli are formed postnatally, and changes