separation over a 100% nonpolar column (dimethylpolysiloxane). voc (volatile organic compounds) are all compounds that appear in the gas chromatogram between and including n-hexane and n-hexadecane. compounds appearing earlier are called vvoc (very volatile organic compounds); compounds appearing later are called svoc (semi-volatile organic compounds). france, germany (agbb/dibt), belgium, norway (tek regulation), and italy (cam edilizia) have enacted regulations to limit voc emissions from commercial products. european industry has developed numerous voluntary ecolabels and rating systems, such as emicode, m1, blue angel, gut (textile floor coverings), nordic swan ecolabel, eu ecolabel, and indoor air comfort. in the united states, several standards exist; california standard cdph section 01350 is the most common one. these regulations and standards changed the marketplace, leading to an increasing number of low-emitting products. health risks respiratory, allergic, or immune effects in infants or children are associated with man-made vocs and other indoor or outdoor air pollutants. some vocs, such as styrene and limonene, can react with nitrogen oxides or with ozone to produce new oxidation products and secondary aerosols, which can cause sensory irritation symptoms. vocs contribute to the formation of tropospheric ozone and smog. health effects include eye, nose, and throat irritation; headaches, loss of coordination, nausea; and damage to the liver, kidney, and central nervous system. some organics can cause cancer in animals; some are suspected or known to cause cancer in humans. key signs or symptoms associated with exposure to vocs include conjunctival irritation, nose and throat discomfort, headache, allergic skin reaction, dyspnea, declines in serum cholinesterase levels, nausea, vomiting, nose bleeding, fatigue, dizziness. the ability of organic chemicals to cause health effects varies greatly from those that are highly toxic to those with no known health effects. as with other pollutants, the extent and nature of the health effect will depend on many factors including level of exposure and length of time exposed. eye and respiratory tract irritation, headaches, dizziness, visual disorders, and memory impairment are among the immediate symptoms that some people have experienced soon after exposure to some organics. at present, not much is known about what health effects occur from the levels of organics usually found in homes. ingestion while null in comparison to the concentrations found in indoor air, benzene, toluene, and methyl tert-butyl ether (mtbe) were found in samples of human milk and increase the concentrations of vocs that we are exposed to throughout the day. a study notes the difference between vocs in alveolar breath and inspired air suggesting that vocs are ingested, metabolized, and excreted via the extra-pulmonary pathway. vocs are also ingested by drinking water in varying concentrations. some voc concentrations were over the epa’s national primary drinking water regulations and china’s national drinking water standards set by the ministry of ecology and environment. dermal absorption the presence of vocs in the air and in groundwater has prompted more studies. several studies have been performed to measure the effects of dermal absorption of specific vocs. dermal exposure to vocs like formaldehyde and toluene downregulate antimicrobial peptides on the skin like cathelicidin ll-37, human β-defensin 2 and 3. xylene and formaldehyde worsen allergic inflammation in animal models. toluene also increases the dysregulation of filaggrin: a key protein in dermal regulation. this was confirmed by immunofluorescence to confirm protein loss and western blotting to confirm mrna loss. these experiments were done on human skin samples. toluene exposure also decreased the water in the trans-epidermal layer allowing for vulnerability in the skin’s layers. limit values for voc emissions limit values for voc emissions into indoor air are published by agbb, afsset, california department of public health, and others. these regulations have prompted several companies in the paint and adhesive industries to adapt with voc level reductions their products. voc labels and certification programs may not properly assess all of the vocs emitted from the product, including some chemical compounds that may be relevant for indoor air quality. each ounce of colorant added to tint paint may contain between 5 and 20 grams of vocs. a dark color, however, could require 5–15 ounces of colorant, adding up to 300 or more grams of vocs per gallon of paint. vocs in healthcare settings vocs are also found in hospital and health care environments. in these settings, these chemicals are widely used for cleaning, disinfection, and hygiene of the different areas. thus, health professionals such as nurses, doctors, sanitation staff, etc., may present with adverse health effects such as asthma; however, further evaluation is required to determine the exact levels and determinants that influence the exposure to these compounds. studies have shown that the concentration levels of different vocs such as halogenated and aromatic hydrocarbons differ substantially between areas of the same hospital. however, one of these studies reported that ethanol, isopropanol, ether, and acetone were the main compounds in the interior of the site. following the same line, in a study conducted in the united states, it was established that nursing assistants are the most exposed to compounds such as ethanol, while medical equipment preparers are most exposed to 2-propanol. in relation to exposure to vocs by cleaning and hygiene personnel, a study conducted in 4 hospitals in the united states established that sterilization and disinfection workers are linked to exposures to d-limonene and 2-propanol, while those responsible for cleaning with chlorine-containing products are more likely to have higher levels of exposure to α-pinene and chloroform. those who perform floor and other surface cleaning tasks (e.g., floor waxing) and who use quaternary ammonium, alcohol, and chlorine-based products are associated with a higher voc exposure than the two previous groups, that is, they are particularly linked to exposure to acetone, chloroform, α-pinene, 2-propanol or d-limonene. other healthcare environments such as nursing and age care homes have been rarely a subject of study, even though the elderly and vulnerable populations may spend considerable time in these indoor settings where they might be exposed to vocs, derived from the common use of cleaning agents, sprays and fresheners. in a study conducted in france, a team of researchers developed an online questionnaire for different social and age care facilities, asking about cleaning practices, products used, and the frequency of these activities. as a result, more than 200 chemicals were identified, of which 41 are known to have adverse health effects, 37 of them being vocs. the health effects include skin sensitization, reproductive and organ-specific toxicity, carcinogenicity, mutagenicity, and endocrine-disrupting properties. furthermore, in another study carried out in the same european country, it was found that there is a significant association between breathlessness in the elderly population and elevated exposure to vocs such as toluene and o-xylene, unlike the remainder of the population. analytical methods sampling obtaining samples for analysis is challenging. vocs, even when at dangerous levels, are dilute, so preconcentration is typically required. many components of the atmosphere are mutually incompatible, e.g. ozone and organic compounds, peroxyacyl nitrates and many organic compounds. furthermore, collection of vocs by condensation in cold traps also accumulates a large amount of water, which generally must be removed selectively, depending on the analytical techniques to be employed. solid-phase microextraction (spme) techniques are used to collect vocs at low concentrations for analysis. as applied to breath analysis, the following modalities are employed for sampling: gas sampling bags, syringes, evacuated steel and glass containers. principle and measurement methods in the u.s., standard methods have been established by the national institute for occupational safety and health (niosh) and another by u.s. osha. each method uses a single component solvent; butanol and hexane cannot be sampled, however, on the same sample matrix using the niosh or osha method. vocs are quantified and identified by two broad techniques. the major technique is gas chromatography (gc). gc instruments allow the separation of gaseous components. when coupled to a flame ionization detector (fid) gcs can detect hydrocarbons at the parts per trillion levels. using electron capture detectors, gcs are also effective for organohalide such as chlorocarbons. the second major technique associated with voc analysis is mass spectrometry, which is usually coupled with gc, giving the hyphenated technique of gc-ms. direct injection mass spectrometry techniques are frequently utilized for the rapid detection and accurate quantification of vocs. ptr-ms is among the methods that have been used most extensively for the on-line analysis of biogenic and anthropogenic vocs. ptr-ms instruments based on time-of-flight mass spectrometry have been reported to reach detection limits of 20 pptv after 100 ms and 750 ppqv after 1 min. measurement (signal integration) time. the mass resolution of these devices is between 7000 and 10,500 m/δm, thus it is possible to separate most common isobaric vocs and quantify them independently. chemical fingerprinting and breath analysis the exhaled human breath contains a few thousand volatile organic compounds and is used in breath biopsy to serve as a voc biomarker to test for diseases, such as lung cancer. one study has shown that "volatile organic compounds ... are mainly blood borne and therefore enable monitoring of different processes in the body." and it appears that voc compounds in the body "may be either produced by metabolic processes or inhaled/absorbed from exogenous sources" such as environmental tobacco smoke. chemical fingerprinting and breath analysis of volatile organic compounds has also been demonstrated with chemical sensor arrays, which utilize pattern recognition for detection of component volatile organics in complex mixtures such as breath gas. metrology for voc measurements to achieve comparability of voc measurements, reference standards traceable to si-units are required. for a number of vocs gaseous reference standards are available from specialty gas suppliers or national metrology institutes, either in the form of cylinders or dynamic generation methods. however, for many vocs, such as oxygenated vocs, monoterpenes, or formaldehyde, no standards are available at the appropriate amount of fraction due to the chemical reactivity or adsorption of these molecules. currently, several national metrology institutes are working on the lacking standard gas mixtures at trace level concentration, minimising adsorption processes, and improving the zero gas. the final scopes are for the traceability and the long-term stability of the standard gases to be in accordance with the data quality objectives (dqo, maximum uncertainty of 20% in this case) required by the wmo/gaw program.