Low-smoke chulha in Indian slums: study protocol for a randomised controlled trial Assessing the Impact of Water Filters and Improved Cook Stoves on Drinking Water Quality and Household Air Pollution: A Randomised Controlled Trial in Rwanda Improving household air, drinking water and hygiene in rural Peru: a community-randomized–controlled trial of an integrated environmental home-based intervention package to improve child health Chimney Stove Intervention to Reduce Long-term Wood Smoke Exposure Lowers Blood Pressure among Guatemalan Women Personal child and mother carbon monoxide exposures and kitchen levels: Methods and results from a randomized trial of woodfired chimney cookstoves in Guatemala (RESPIRE) Health and Climate-Relevant Pollutant Concentrations from a Carbon-Finance Approved Cookstove Intervention in Rural India. Impact of the Improved Patsari Biomass Stove on Urinary Polycyclic Aromatic Hydrocarbon Biomarkers and Carbon Monoxide Exposures in Rural Mexican Women Impact of Reduced Maternal Exposures to Wood Smoke from an Introduced Chimney Stove on Newborn Birth Weight in Rural Guatemala The intensive margin of technology adoption--Experimental evidence on improved cooking stoves in rural Senegal. Children’s Respiratory Health After an Efficient Biomass Stove (Patsari) Intervention Feasibility of conducting a randomised controlled trial of a cookstove intervention in rural Malawi A cleaner burning biomass-fuelled cookstove intervention to prevent pneumonia in children under 5 years old in rural Malawi (the Cooking and Pneumonia Study): a cluster randomised controlled trial Longitudinal Relationship between Personal CO and Personal PM2.5 among Women Cooking with Woodfired Cookstoves in Guatemala Improved biomass stove intervention in rural Mexico: impact on the respiratory health of women. Combining Individual- and Group-Level Exposure Information: Child Carbon Monoxide in the Guatemala Woodstove Randomized Control Trial Effect of reducing indoor air pollution on women's respiratory symptoms and lung function: the RESPIRE Randomized Trial, Guatemala. Effect of reduction in household air pollution on childhood pneumonia in Guatemala (RESPIRE): a randomised controlled trial Eye discomfort, headache and back pain among Mayan Guatemalan women taking part in a randomised stove intervention trial
Background Biomass fuel is used as a primary cooking source by more than half of the world ’s population , contributing to a high burden of disease . Although cleaner fuels are available , some households continue using solid fuels because of financial constraints and absence of infrastructure , especially in non-notified slums . The present study documents a r and omised controlled study investigating the efficacy of improved cookstove on the personal exposure to air pollution and the respiratory health of women and children in an Indian slum . The improved cookstove was based on co-creation of a low-smoke chulha with local communities in order to support adaption and sustained uptake . Methods The study will be conducted in a non-notified slum called Ashrayanagar in Bangalore , India . The study design will be a 1:1 r and omised controlled intervention trial , including 250 households . The intervention group will receive an improved cookstove ( low-smoke chulha ) and the control group will continue using either the traditional cookstove ( chulha ) or a combination of the traditional stove and the kerosene/diesel stove . Follow-up time is 1 year . Outcomes include change in lung function ( FEV1/FVC ) , incidence of pneumonia , change in personal PM2.5 and CO exposure , incidence of respiratory symptoms ( cough , phlegm , wheeze and shortness of breath ) , prevalence of other related symptoms ( headache and burning eyes ) , change in behaviour and adoption of the stove . Ethical clearance was obtained from the Institutional Ethics Committee of the Indian Institute of Public Health Hyderabad- Bengaluru Campus . Discussion The findings from this study aim to provide insight into the effects of improved cookstoves in urban slums . Results can give evidence for the decrease of indoor air pollution and the improvement of respiratory health for children and women . Trial registration The trial was registered with clinical trials.gov on 21 June 2016 with the identifier NCT02821650 ; A Study to Test the Impact of an Improved Chulha on the Respiratory Health of Women and Children in Indian Slums Diarrhoea and respiratory infections remain the biggest killers of children under 5 years in developing countries . We conducted a 5-month household r and omised controlled trial among 566 households in rural Rw and a to assess uptake , compliance and impact on environmental exposures of a combined intervention delivering high-performance water filters and improved stoves for free . Compliance was measured monthly by self-report and spot-check observations . Semi-continuous 24-h PM2.5 monitoring of the cooking area was conducted in a r and om sub sample of 121 households to assess household air pollution  , while sample s of drinking water from all households were collected monthly to assess the levels of thermotolerant coliforms . Adoption was generally high , with most householders reporting the filters as their primary source of drinking water and the intervention stoves as their primary cooking stove . However , some householders continued to drink untreated water and most continued to cook on traditional stoves . The intervention was associated with a 97.5 % reduction in mean faecal indicator bacteria ( Williams means 0.5 vs. 20.2 TTC/100 mL , p<0.001 ) and a median reduction of 48 % of 24-h PM2.5 concentrations in the cooking area ( p = 0.005 ) . Further studies to increase compliance should be undertaken to better inform large-scale interventions . Trial registration : Clinical trials.gov ; NCT01882777 ; http:// clinical trials.gov/ct2/ results ? term = NCT01882777 & Search = Abstract Background : Diarrhoea and acute lower respiratory infections are leading causes of childhood morbidity and mortality , which can be prevented by simple low-cost interventions . Integrated strategies can provide additional benefits by addressing multiple health burdens simultaneously . Methods : We conducted a community-r and omized – controlled trial in 51 rural communities in Peru to evaluate whether an environmental home-based intervention package , consisting of improved solid-fuel stoves , kitchen sinks , solar disinfection of drinking water and hygiene promotion , reduces lower respiratory infections , diarrhoeal disease and improves growth in children younger than 36 months . The attention control group received an early child stimulation programme . Results : We recorded 24 647 child-days of observation from 250 households in the intervention and 253 in the attention control group during 12-month follow-up  . Mean diarrhoea incidence was 2.8 episodes per child-year in the intervention compared with 3.1 episodes in the control arm . This corresponds to a relative rate of 0.78 [ 95 % confidence interval ( CI ) : 0.58–1.05 ] for diarrhoea incidence and an odds ratio of 0.71 ( 95 % CI : 0.47–1.06 ) for diarrhoea prevalence . No effects on acute lower respiratory infections or children ’s growth rates were observed . Conclusions : Combined home-based environmental interventions slightly reduced  childhood diarrhoea , but the confidence interval included unity . Effects on growth and respiratory outcomes were not observed , despite high user compliance of the interventions . The absent effect on respiratory health might be due to insufficient household air quality improvements of the improved stoves and additional time needed to achieve attitudinal and behaviour change when providing composite interventions Background and Objective RESPIRE , a r and omized trial of an improved cookstove , was conducted in Guatemala to assess health effects of long-term reductions in wood smoke exposure . Given the evidence that ambient particles increase blood pressure , we hypothesized that the intervention would lower blood pressure . Methods Two study design s were used : a ) between-group comparisons based on r and omized stove assignment , and b ) before- and -after comparisons within subjects before and after they received improved stoves . From 2003 to 2005 , we measured personal fine particle ( particulate matter with aerodynamic diameter < 2.5 μm ; PM2.5 ) exposures and systolic ( SBP ) and diastolic blood pressure ( DBP ) among women > 38 years of age from the chimney woodstove intervention group ( 49 subjects ) and traditional open wood fire control group ( 71 subjects ) . Measures were repeated up to three occasions . Results Daily average PM2.5 exposures were 264 and 102 μg/m3 in the control and intervention groups , respectively . After adjusting for age , body mass index , an asset index , smoking , secondh and tobacco smoke , apparent temperature , season , day of week , time of day , and a r and om subject intercept , the improved stove intervention was associated with 3.7 mm Hg lower SBP [ 95 % confidence interval ( CI ) , −8.1 to 0.6 ] and 3.0 mm Hg lower DBP ( 95 % CI , −5.7 to −0.4 ) compared with controls . In the second study design , among 55 control subjects measured both before and after receiving chimney stoves , similar associations were observed . Conclusion The between-group comparisons provide evidence , particularly for DBP , that the chimney stove reduces blood pressure , and the before- and -after comparisons are consistent with this evidence During the first r and omized intervention trial ( RESPIRE : R and omized Exposure Study of Pollution Indoors and Respiratory Effects ) in air pollution epidemiology , we pioneered application of passive carbon monoxide ( CO ) diffusion tubes to measure long-term personal exposures to woodsmoke . Here we report on the protocol s and validations of the method , trends in personal exposure for mothers and their young children , and the efficacy of the introduced improved chimney stove in reducing personal exposures and kitchen concentrations . Passive diffusion tubes originally developed for industrial hygiene applications were deployed on a quarterly basis to measure 48-hour integrated personal carbon monoxide exposures among 515 children 0 - 18 months of age and 532 mothers aged 15 - 55 years and area sample s in a sub sample of 77 kitchens , in households r and omized into control and intervention groups . Instrument comparisons among types of passive diffusion tubes and against a continuous electrochemical CO monitor indicated that tubes responded nonlinearly to CO , and regression calibration was used to reduce this bias . Before stove introduction , the baseline arithmetic ( geometric ) mean 48-h child ( n=270 ) , mother ( n=529 ) and kitchen ( n=65 ) levels were , respectively , 3.4 ( 2.8 ) , 3.4 ( 2.8 ) and 10.2 ( 8.4 ) p.p.m . The between-group analysis of the 3355 post-baseline measurements found CO levels to be significantly lower among the intervention group during the trial period : kitchen levels : −90 % ; mothers : −61 % ; and children : −52 % in geometric means . No significant deterioration in stove effect was observed over the 18 months of surveillance . The reliability of these findings is strengthened by the large sample size made feasible by these unobtrusive and inexpensive tubes , measurement error reduction through instrument calibration , and a r and omized , longitudinal study design . These results from the first r and omized trial of improved household energy technology in a developing country and demonstrate that a simple chimney stove can substantially reduce chronic exposures to harmful indoor air pollutants among women and infants Efforts to introduce more efficient stoves increasingly leverage carbon-finance to scale up dissemination of interventions . We conducted a r and omized intervention study to evaluate a Clean Development Mechanism approved stove replacement impact on fuelwood usage , and climate and health-relevant air pollutants . We r and omly assigned 187 households to either receive the intervention or to continue using traditional stoves .  Measurements of fine particulate matter ( PM2.5 ) and absorbance were conducted in cooking areas , village center and at upwind background site . There were minor and overlapping seasonal differences ( post- minus preintervention change ) between control and intervention groups for median ( 95 % CI ) fuel use ( -0.60 ( -1.02 , -0.22 ) vs -0.52 ( -1.07 , 0.00 ) kg day(-1 ) ) , and 24 h absorbance ( 35 ( 18 , 60 ) vs 36 ( 22 , 50 ) × 10(-6 ) m(-1 ) ) ; for 24 h PM2.5 , there was a higher ( 139 ( 61,229 ) vs 73(-6 , 156 ) μg m(-3 ) ) ) increase in control compared to intervention homes between the two seasons . Forty percent of the intervention homes continued using traditional stoves . For intervention homes , absorbance-to-mass ratios suggest a higher proportion of black carbon in PM2.5 emitted from intervention compared with traditional stoves . Absent of field-based evaluation , stove interventions may be pursued that fail to realize expected carbon reductions or anticipated health and climate co benefits Background : Cooking with biomass fuels on open fires results in exposure to health-damaging pollutants such as carbon monoxide ( CO ) , polycyclic aromatic hydrocarbons ( PAHs ) , and particulate matter . Objective : We compared CO exposures and urinary PAH biomarkers pre- and postintervention with an improved biomass stove , the Patsari stove . Methods : In a sub sample of 63 women participating in a r and omized controlled trial in central Mexico , we measured personal CO exposure for 8 hr during the day using continuous monitors and passive sample rs . In addition , first-morning urine sample s obtained the next day were analyzed for monohydroxylated PAH metabolites by gas chromatography/isotope dilution/high-resolution mass spectrometry . Exposure data were collected during the use of an open fire ( preintervention ) and after installation of the improved stove ( postintervention ) for 47 women , enabling paired comparisons . Results : Median pre- and postintervention values were 4 and 1 ppm for continuous personal CO and 3 and 1 ppm for passive sample r CO , respectively . Postintervention measurements indicated an average reduction of 42 % for hydroxylated metabolites of naphthalene , fluorene , phenanthrene , and pyrene on a whole-weight concentration basis ( micrograms per liter of urine ) , and a 34 % reduction on a creatinine-adjusted basis ( micrograms per gram of creatinine ) . Pre- and postintervention geometric mean values for 1-hydroxypyrene were 3.2 and 2.0 μg/g creatinine , respectively . Conclusion : Use of the Patsari stove significantly reduced CO and  PAH exposures in women . However , levels of many PAH biomarkers remained higher than those reported among smokers Background : A growing body of evidence indicates a relationship between household indoor air pollution from cooking fires and adverse neonatal outcomes , such as  low birth weight ( LBW )  , in re source -poor countries . Objective : We examined the effect of reduced wood smoke exposure in pregnancy on LBW  of Guatemalan infants in RESPIRE ( R and omized Exposure Study of Pollution Indoors and Respiratory Effects ) . Methods : Pregnant women ( n = 266 ) either received a chimney stove ( intervention ) or continued to cook over an open fire ( control ) . Between October 2002 and December 2004 we weighed 174 eligible infants ( 69 to mothers who used a chimney stove and 105 to mothers who used an open fire during pregnancy ) within 48 hr of birth . Multivariate linear regression and adjusted odds ratios ( ORs ) were used to estimate differences in birth weight and LBW ( < 2,500 g ) associated with chimney-stove versus open-fire use during pregnancy . Results : Pregnant women using chimney stoves had a 39 % reduction in mean exposure to carbon monoxide compared with those using open fires . LBW prevalence was high at 22.4 % . On average , infants born to mothers who used a stove weighed 89 g more [ 95 % confidence interval ( CI ) , –27 to 204 g ] than infants whose mothers used open fires after adjusting for maternal height , diastolic blood pressure , gravidity , and season of birth . The adjusted OR for LBW was 0.74 ( 95 % CI , 0.33–1.66 ) among infants of stove users compared with open-fire users . Average birth weight was 296 g higher ( 95 % CI , 109–482 g ) in infants born during the cold season ( after harvest ) than in other infants ; this unanticipated finding may reflect the role of maternal nutrition on birth weight in an impoverished region . Conclusions : A chimney stove reduced wood smoke exposures and was associated with reduced LBW occurrence . Although not statistically significant , the estimated effect was consistent with previous studies Today , almost 3 billion people in developing countries rely on biomass as primary cooking fuel , with profound negative implication s for their well-being . Improved biomass cooking stoves are alleged to counteract these adverse effects . This paper evaluates take-up and impacts of low-cost improved stoves through a r and omized controlled trial . The r and omized stove is primarily design ed to curb firewood consumption , but not smoke emissions . Nonetheless , we find considerable effects not only on firewood consumption , but also on smoke exposure and , consequently , smoke-related disease symptoms . The reduced smoke exposure results from behavioural changes in terms of increased outside cooking and a reduction in cooking time . We conclude that in order to assess the effectiveness of a technology-oriented intervention , it is critical to not only account for the incidence of technology adoption - the extensive margin - but also for the way the new technology is used - the intensive margin Household use of fuelwood represents a socio-ecological condition with important health effects mainly in rural areas from developing countries . One approach to tackle this problem has been the introduction of efficient wood-burning chimney stoves . The aim of this study was to assess the impact of the introduction of Patsari stoves on the respiratory health of young children in highl and s Michoacán , Mexico . A total of 668 households in six rural communities in a fuelwood using region were selected and r and omized to receive an improved stove ( Patsari ) or rely entirely on the traditional wood fire until the end of the follow-up including 10 monthly visits . Adherence to the intervention was variable over the follow-up time . The actual use of the Patsari stove as reported by the mother showed a protective effect mainly on the upper and lower respiratory infection duration ( IRR URI 0.79 , 95 % CI 0.70–0.89 , and LRI 0.41 , 95 % CI 0.21–0.80 ) compared to households that used only an open fire . Fewer days of child ’s ill health represents saved time for the woman and avoided disease treatment costs for the family , as well as a decrease in public health costs due to a reduction in the frequency of patient visits BACKGROUND : Exposure to household air pollution ( HAP ) causes 4 million deaths annually , and strategies to reduce HAP exposure are urgently required . OBJECTIVE : To evaluate the acceptability and feasibility of conducting a trial of a cookstove intervention in rural Malawi . DESIGN : Non-smoking women were r and omised to continuing to use an open fire ( control ) or to using a wood-burning clay cookstove ( intervention )  . Symptom burden , oxygen saturation and exhaled carbon monoxide ( eCO ) were assessed at baseline and 7-day follow-up . A subset of women underwent HAP exposure monitoring . RESULTS : Of 51 women recruited , 50 ( 98 % ) completed the main study . The methodology was acceptable to participants . Headache , back pain and cough were the most commonly reported symptoms at baseline and follow-up . Median eCO was within normal limits , but with a difference of 0.5 parts per million ( ppm ) in median change of eCO from baseline to follow-up seen between the two groups ( P ∙ 0.035 ) . The peak ambient CO concentration detected was 150 ppm . CONCLUSION : This study suggests that a large cookstove intervention trial in Malawi would be feasible with careful community sensitisation . Monitoring exposure to HAP is challenging , and further studies evaluating potential biomarkers of exposure , including eCO , should be undertaken Summary Background WHO estimates exposure to air pollution from cooking with solid fuels is associated with over 4 million premature deaths worldwide every year including half a million children under the age of 5 years from pneumonia . We hypothesised that replacing open fires with cleaner burning biomass-fuelled cookstoves would reduce pneumonia incidence in young children . Methods We did a community-level open cluster r and omised controlled trial to compare the effects of a cleaner burning biomass-fuelled cookstove intervention to continuation of open fire cooking on pneumonia in children living in two rural districts , Chikhwawa and Karonga , of Malawi . Clusters were r and omly allocated to intervention and control groups using a computer-generated r and omisation schedule with stratification by site , distance from health centre , and size of cluster . Within clusters , households with a child under the age of 4·5 years were eligible . Intervention households received two biomass-fuelled cookstoves and a solar panel . The primary outcome was WHO Integrated Management of Childhood Illness (IMCI)-defined pneumonia episodes in children under 5 years of age . Efficacy and safety analyses were by intention to treat . The trial is registered with IS RCT N , number IS RCT N59448623 . Findings We enrolled 10 750 children from 8626 households across 150 clusters between Dec 9 , 2013 , and Feb 28 , 2016 . 10 543 children from 8470 households contributed 15 991 child-years of follow-up data to the intention-to-treat analysis . The IMCI pneumonia incidence rate in the intervention group was 15·76 ( 95 % CI 14·89–16·63 ) per 100 child-years and in the control group 15·58 ( 95 % CI 14·72–16·45 ) per 100 child-years , with an intervention versus control incidence rate ratio ( IRR ) of 1·01 ( 95 % CI 0·91–1·13 ; p=0·80 ) . Cooking-related serious adverse events ( burns ) were seen in 19 children ; nine in the intervention and ten ( one death ) in the control group ( IRR 0·91 [ 95 % CI 0·37–2·23 ] ; p=0·83 ) . Interpretation We found no evidence that an intervention comprising cleaner burning biomass-fuelled cookstoves reduced the risk of  pneumonia in young children in rural Malawi . Effective strategies to reduce the adverse health effects of household air pollution are needed . Funding Medical Research Council , UK Department for International Development , and Wellcome Trust Household air pollution ( HAP ) due to solid fuel use is a major public health threat in low-income countries . Most health effects are thought to be related to exposure to the fine particulate matter ( PM ) component of HAP , but it is currently impractical to measure personal exposure to PM in large studies . Carbon monoxide ( CO ) has been shown in cross-sectional analyses to be a reliable surrogate for particles<2.5 µm in diameter ( PM2.5 ) in kitchens where wood-burning cookfires are a dominant source , but it is unknown whether a similar PM2.5-CO relationship exists for personal exposures longitudinally . We repeatedly measured ( 216 measures , 116 women ) 24-hour personal  PM2.5  ( median [ IQR ] = 0.11 [ 0.05 , 0.21 ] mg/m3 ) and CO ( median [ IQR ] = 1.18 [ 0.50 , 2.37 ] mg/m3 ) among women cooking over open woodfires or chimney woodstoves in Guatemala . Pollution measures were natural-log transformed for analyses . In linear mixed effects models with r and om subject intercepts , we found that personal CO explained 78 % of between-subject variance in personal PM2.5 . We did not see a difference in slope by stove type . This work provides evidence that in setting s where there is a dominant source of biomass combustion , repeated measures of personal CO can be used as a reliable surrogate for an individual 's PM2.5 exposure . This finding has important implication s for the feasibility of reliably estimating long-term ( months to years ) PM2.5 exposure in large-scale epidemiological and intervention studies of HAP RATIONALE Exposure to biomass smoke has been related to adverse health effects . In Mexico , one household in four still cooks with biomass fuel , but there has been no evaluation of the health impact of reducing indoor air pollution . OBJECTIVES To evaluate the health impact of the introduction of an improved biomass stove ( Patsari ; Interdisciplinary Group for Appropriate Rural Technology [ GIRA ] , Patzcuaro , Mexico ) in Mexican women . METHODS A r and omized controlled trial was conducted in the Central Mexican state of Michoacán . Households were r and omized to receive the Patsari stove or keep their traditional open fire . A total of 552 women were followed with monthly visits over 10 months to assess stove use , inquire about respiratory and other symptoms , and obtain lung function measurements . Statistical analysis was conducted using longitudinal models . MEASUREMENTS AND MAIN RESULTS Adherence to the intervention was low ( 50 % ) . Women who reported using the Patsari stove most of the time compared with those using the open fire had significantly lower risk of respiratory symptoms ( relative risk [ RR ] , 0.77 ; 95 % confidence interval [ CI ] , 0.62 - 0.95 for cough and RR , 0.29 ; 95 % CI , 0.11 - 0.77 for wheezing ) adjusted for confounders . Similar results were found for other respiratory symptoms as well as for eye discomfort , headache , and back pain . Actual use of the Patsari stove was associated with a lower FEV(1 ) decline ( 31 ml ) compared with the open fire use ( 62 ml ) over 1 year of follow-up ( P = 0.012 ) for women 20 years of age and older , adjusting for confounders . CONCLUSIONS The use of the Patsari stove was significantly associated with a reduction of symptoms and of lung function decline comparable to smoking cessation Background : Epidemiology frequently relies on surrogates of long-term exposures , often either individual-level short-term measurements or group-level based on long-term characteristics of subjects and their environment . Whereas individual-level measures are often imprecise due to within-subject variability , group-level measures tend to be inaccurate due to residual between-subject variability within groups . Rather than choose between these error-prone estimates , we borrow strength from each by use of mixed-model prediction and we compare the predictive validity . Methods : We compared alternative measures of long-term exposure to carbon monoxide ( CO ) among children in the RESPIRE woodstove r and omized control trial during years 2003 and 2004 . The main study included 1932 repeated 48-hour-average personal CO measures among 509 children from 0–18 months of age . We used a validation study with additional CO measures among a r and om sub sample of 70 of the children to compare the predictive validity of individual-level estimates ( based on observed short-term exposures ) , group-level estimates ( based on stove type and other residential characteristics ) , and mixed-model predictions that combine these 2 sources of information . Results : The estimated error variance for mixed-model prediction was 63 % lower than the individual-level measure based on the exposure data and 58 % lower than the corresponding group-level measure . Conclusions : When both individual- and group-level estimates are available but imperfect , mixed-model prediction may provide substantially better measures of long-term exposure , potentially increasing the sensitivity of epidemiologic studies to underlying causal relations Exposure to household wood smoke from cooking is a risk factor for chronic obstructive lung disease among women in developing countries . The R and omized Exposure Study of Pollution Indoors and Respiratory Effects ( RESPIRE ) is a r and omized intervention trial evaluating the respiratory health effects of reducing indoor air pollution from open cooking fires . A total of 504 rural Mayan women in highl and Guatemala aged 15 - 50 years , all using traditional indoor open fires , were r and omized to either receive a chimney woodstove ( plancha ) or continue using the open fire . Assessment s of chronic respiratory symptoms and lung function and individual measurements of carbon monoxide exposure were performed at baseline and every 6 months up to 18 months . Use of a plancha significantly reduced carbon monoxide exposure by 61.6 % . For all respiratory symptoms , reductions in risk were observed in the plancha group during follow-up ; the reduction was statistically significant for wheeze ( relative risk = 0.42 , 95 % confidence interval : 0.25 , 0.70 ) . The number of respiratory symptoms reported by the women at each follow-up point was also significantly reduced by the plancha ( odds ratio = 0.7 , 95 % confidence interval : 0.50 , 0.97 ) . However , no significant effects on lung function were found after 12 - 18 months . Reducing indoor air pollution from household biomass burning may relieve symptoms consistent with chronic respiratory tract irritation BACKGROUND Pneumonia causes more child deaths than does any other disease . Observational studies have indicated that smoke from household solid fuel is a significant risk factor that affects about half the world 's children . We investigated whether an intervention to lower indoor wood smoke emissions would reduce pneumonia in children . METHODS We undertook a parallel r and omised controlled trial in highl and Guatemala , in a population using open indoor wood fires for cooking . We r and omly assigned 534 households with a pregnant woman or young infant to receive a woodstove with chimney ( n=269 ) or to remain as controls using open woodfires ( n=265 ) , by concealed permuted blocks of ten homes . Fieldworkers visited homes every week until children were aged 18 months to record the child 's health status . Sick children with cough and fast breathing , or signs of severe illness were referred to study physicians , masked to intervention status , for clinical examination . The primary outcome was physician-diagnosed pneumonia , without use of a chest radiograph . Analysis was by intention to treat ( ITT ) . Infant 48-h carbon monoxide measurements were used for exposure-response analysis after adjustment for covariates . This trial is registered , number IS RCT N29007941 . FINDINGS During 29,125 child-weeks of surveillance of 265 intervention and 253 control children , there were 124 physician-diagnosed pneumonia cases in intervention households and 139 in control households ( rate ratio [ RR ] 0·84 , 95 % CI 0·63 - 1·13 ; p=0·257 ) . After multiple imputation , there were 149 cases in intervention households and 180 in controls ( 0·78 , 0·59 - 1·06 , p=0·095 ; reduction 22 % , 95 % CI -6 % to 41 % ) . ITT analysis was undertaken for secondary outcomes : all and severe fieldworker-assessed pneumonia ; severe ( hypoxaemic ) physician-diagnosed pneumonia ; and radiologically confirmed , RSV-negative , and RSV-positive pneumonia , both total and severe . We recorded significant reductions in the intervention group for three severe outcomes -fieldworker-assessed , physician-diagnosed , and RSV-negative pneumonia -- but not for others . We identified no adverse effects from the intervention . The chimney stove reduced exposure by 50 % on average ( from 2·2 to 1·1 ppm carbon monoxide ) , but exposure distributions for the two groups overlapped substantially . In exposure-response analysis , a 50 % exposure reduction was significantly associated with physician-diagnosed pneumonia ( RR 0·82 , 0·70 - 0·98 ) , the greater precision result ing from less exposure misclassification compared with use of stove type alone in ITT analysis . INTERPRETATION In a population heavily exposed to wood smoke from cooking , a reduction in exposure achieved with chimney stoves did not significantly reduce physician-diagnosed pneumonia for children younger than 18 months . The significant reduction of a third in severe pneumonia , however , if confirmed , could have important implication s for reduction of child mortality . The significant exposure-response associations contribute to causal inference and suggest that stove or fuel interventions producing lower average exposures than these chimney stoves might be needed to substantially reduce pneumonia in population s heavily exposed to biomass fuel air pollution . FUNDING US National Institute of Environmental Health Sciences and WHO Background : Indoor air pollution ( IAP ) from combustion of biomass fuels represents a global health problem , estimated to cause 1.6 million premature deaths annually . Aims : RESPIRE ( R and omised Exposure Study of Pollution Indoors and Respiratory Effects ) Guatemala is the first r and omised controlled trial ever performed on health effects from solid fuel use . Its goal is to assess the effect of improved stoves ( planchas ) on exposure and health outcomes in a rural population reliant on wood fuel . Methods : Questions about symptoms were asked at baseline and periodically after the intervention , to an initial group of 504 women ( 259 r and omly assigned to planchas ( mean ( st and ard deviation ) age 27.4 ( 7.2 ) years ) and 245 using traditional open fires ( 28.1 ( 7.1 ) years ) ) .  Levels of carbon monoxide ( CO ) in exhaled breath , a biomarker of recent exposure to air pollution from biomass combustion , were measured at each visit . In addition to reducing IAP levels , the plancha may also have a positive health effect by changing the working posture to an upright position . Results : A high prevalence of eye discomfort , headache and backache was found . The odds of having sore eyes and headache were substantially reduced in the plancha group relative to the group using open fires for the follow-up period ( odds ratio ( OR ) 0.18 , 95 % confidence interval ( CI ) 0.11 to 0.29 and ( OR ) 0.63 , 95 % CI 0.42 to 0.94 , respectively ) . Median CO in breath among women in the intervention trial was significantly lower than controls . Conclusion : In addition to reducing discomfort for women , tangible improvements in symptoms experienced by a substantial proportion of women may help to gain acceptance and wider use of planchas
Objectives Improved biomass cookstoves may help reduce the substantial global burden of morbidity and mortality due to household air pollution ( HAP ) that disproportionately affects women and children in low and middle income countries ( LMICs ) .