Filter-based optical techniques compare light transmission intensities between loaded (I) and unloaded (I0) filters as a measure of light-absorbing mass for subsequent estimations of equivalent black carbon (eBC). We analyzed 5,379 15 mm Teflon filters from the Household Air Pollution Intervention Network (HAPIN) trial to assess the influence that different methods of I0 estimations have on eBC measures. We compared eBC measurements using filter-specific I0 values (Method 1) to those using three other methods of I0 estimation: the lab blank scan from a given session (Method 2), the average of all pre-sample filter scans (Method 3), and the average of all lab blank filter scans (Method 4). We assessed the agreement between Method 1 and the alternative methods using Bland-Altman analysis. We also assessed the relationship between Method 1 and the alternative methods across the complete measurement range and after stratifying exposure data into quartiles according to Method 1 eBC exposures. The mean (SD) personal eBC exposure for Method 1 was 7.8 μg/m3 (5.9), and exposures ranged from 1.3 to 46.8 μg/m3. Compared to Method 1, eBC using Methods 2, 3, and 4 were higher by 0.7 μg/m3, 0.1 μg/m3, and 0.7 μg/m3, respectively. The performances of linear regression models between Method 1 and all other methods were moderate to strong (R2 range: 0.42-0.93) in the second, third, and fourth quartiles; however, the models in the first quartile (eBC range: 1.3-2.9 μg/m3) performed poorly (R2 = 0.25-0.26), with error approximately 25% of the mean. Our findings suggest that, in most instances, conventional methods for obtaining I0 values can be used to sufficiently characterize eBC; however, analyzing filters before sampling adds appreciably to the accuracy of eBC estimations in lower concentration settings.Implications: Filter-based optical techniques compare light transmission intensities between loaded (I) and unloaded (I0) filters as a measure of light-absorbing mass for subsequent estimations of equivalent black carbon (eBC). To assess the influence that different methods of I0 estimations have on eBC measures, we analyzed 5,379 15 mm Teflon filters from the Household Air Pollution Intervention Network (HAPIN) trial. Our findings suggest that, in most instances, conventional methods for obtaining I0 values can be used to sufficiently characterize eBC; however, analyzing filters before sampling adds appreciably to the accuracy of eBC estimations in lower concentration settings.

Background: Clean fuels and stoves (CF-CS) can reduce household air pollution (HAP) and short-lived climate pollutants (SLCPs), yet measurements of health- and climate-relevant pollutants remain scarce in many settings, including Nigeria. We measured fine particulate matter (PM2.5) and black carbon (BC) to evaluate air quality and climate co-benefits of a clean cooking intervention in Lagos, Nigeria. Methods: Between September 2023 and July 2024, we enrolled 333 peri-urban households participating in a parent cluster-randomized controlled trial (NCT05048147). Households were classified by primary cooking fuel: clean fuels (liquefied petroleum gas or ethanol), mixed fuels (biomass and clean fuels), kerosene only, and kerosene with biomass. PM2.5 and BC were measured over 48 hours using household aerosol samplers. PM2.5 mass was determined gravimetrically, and BC was quantified with a SootScan OT-21 transmissometer. Findings: PM2.5 concentrations exceeded the WHO Interim Target-1 guideline (35 µg/m3) in all fuel groups. Geometric mean PM2.5 concentrations ranged from 85.4 µg/m3 among clean-fuel users to 121.1 µg/m³ in kerosene-with-biomass households. BC concentrations were lowest in clean-fuel households (geometric mean 6.7 µg/m3) and highest among kerosene-with-biomass users (9.7 µg/m3). Estimated BC emissions were 2 g per household annually among clean-fuel users compared with 259 g in mixed-fuel households (>99% attributable to biomass). Elevated pollution levels across groups were associated with stove stacking and ambient air pollution. Modelling suggests that exclusive clean-fuel use could reduce BC emissions by approximately 0.25 kg per household annually, corresponding to 1,500–5,500 metric tons avoided in urban Nigeria. Interpretation: Household air pollution remains high even among clean-fuel users. Accelerating transitions to exclusive clean cooking could deliver substantial health and climate benefits in rapidly urbanizing African settings.

BACKGROUND:Source apportionment is a method that reconstructs sources of pollution from monitored values. The identification of these sources is important to develop interventions and other strategies to improve environmental quality. OBJECTIVE:This study aimed to identify and quantify potential sources that contribute to fine particulate matter (PM2.5) personal exposures in a cohort of pregnant women participating in a fuel-cooking intervention trial in Guatemala. METHODS:We estimated the PM2.5 and black carbon (BC) concentrations from 629 polytetrafluoroethylene (PTFE) filter samples using gravimetric and transmittance analyses, and we analyzed inorganic elements using energy dispersive X-ray fluorescence (ED-XRF). The filters correspond to personal exposure samples collected with the Enhanced Children's MicroPEM™ (ECM) from pregnant women who cook using biomass or liquefied petroleum gas (LPG) fuels within the Household Air Pollution Intervention Network (HAPIN) randomized-controlled trial in rural Jalapa, Guatemala. We used the U.S. Environmental Protection Agency's (EPA) Positive Matrix Factorization (PMF) model to identify the potential sources. RESULTS:A four-factor source apportionment model was derived from PMF. The potential sources and their relative contributions to PM2.5 mass were identified as: biomass burning ( ~ 69.6%), fossil fuels (22%), crustal, and other soil ( ~ 4% each). When categorizing our samples by study group, baseline (155 µg/m3; 95% CI: 129.7, 180.2) and post-intervention control (127.2 µg/m3; 95% CI: 114.7, 139.7) samples had the highest amount of PM2.5 mass (49.7% and 40.7%, respectively) compared to 9.6% (29.9 µg/m3; 95% CI: 27.2, 32.7) from intervention samples. SIGNIFICANCE:We identified biomass burning, fossil fuel burning, crustal and other soil as sources of PM2.5 pollution in rural Jalapa, Guatemala. These findings pave the road for future source apportionment studies in this region and highlight the importance of source characterization to implement interventions to reduce PM2.5 emissions. Sources and average PM2.5 mass contribution in µg/m3 (%) from rural Jalapa, Guatemala. IMPACT:We identified four potential sources of PM2.5 in rural Jalapa, Guatemala, based on personal exposure samples from pregnant women participating in the HAPIN trial. Biomass and fossil fuel burning are the sources with the highest contributions, followed by crustal and other soil. The findings of this study highlight the potential to prioritize emissions reduction efforts in rural Guatemala through the implementation of specific interventions based on the derived sources of pollution.

Indoor nitrogen dioxide (NO _2 ) and fine particulate matter (PM _2.5 ) are concerns in U.S. households, especially those that cook using gas or propane stoves. Exposures to these and other indoor pollutants are linked to a variety of adverse health outcomes, including asthma morbidity, that disproportionately affect low-income households. We conducted a cross-sectional study of 138 homes in four low-income rural communities in California’s San Joaquin Valley, comparing air pollutant concentrations between households that participated in a state electrification program and households using propane or natural gas for cooking. In each home, pollutants were monitored for approximately one month using personal air monitors and for 48 h using reference-grade instruments. Median 48-h average indoor NO _2 concentrations were 63% lower in electric stove homes (electric: 6.0 ppb, gas: 16.0 ppb, p < 0.001). No electric stove homes had 48-h indoor NO _2 concentrations exceeding the California annual guideline of 30 ppb, while 17% of gas homes did. Additionally, no electric stove homes had 1-h rolling-average NO _2 concentrations exceeding the 100-ppb level deemed unhealthy for sensitive groups by the U.S. Environmental Protection Agency, whereas 41% of gas homes exceeded this threshold. PM _2.5 concentrations were similar across groups, indicating that cooking-related emissions from food were the dominant contributor to PM _2.5 mass concentrations rather than particles generated from gas combustion. Our evaluation of monitoring durations showed that two to four days of NO _2 data and one week of PM _2.5 data provided reliable estimates of longer-term averages, suggesting that shorter campaigns may yield robust estimates of indoor air quality. These results support the provision of electric cooking technologies as a strategy to address air quality-related health risks in rural, low-income communities and provide new evidence from an understudied population that can inform future indoor air quality research and energy transition policies.

Importance:Household air pollution from biomass cooking is considered an important risk factor for child pneumonia. Objective:To evaluate the longitudinal association between exposure to particulate matter with a diameter of less than or equal to 2.5 µm (PM2.5) or carbon monoxide (CO) and severe pneumonia in infants. Design, Setting, and Participants:This cohort study included infants (aged ≤12 months) whose mothers participated in a 4-country randomized clinical trial. Conducted from May 2018 to September 2021, the trial tested whether an 18-month liquefied petroleum gas stove and fuel distribution intervention reduced the incidence of severe pneumonia in offspring during infancy when compared with biomass cooking. The trial was conducted in communities where residents cooked primarily with biomass fuels in Guatemala, India, Peru, and Rwanda. Data analysis was conducted from December 2024 to July 2025. Exposures:Twenty-four hour personal exposure to PM2.5 and CO was measured 3 times during pregnancy and 3 times during infancy. Main Outcome and Measures:In this exposure-response analysis, severe pneumonia cases were identified using respiratory signs and symptoms with confirmation of consolidation by imaging and hypoxemia by pulse oximetry. The longitudinal association between severe pneumonia in infants and PM2.5 or CO exposures by infant-quarters, adjusted for confounders, was modeled. Results:Overall, 3061 infants (48.2% girls; mean [SD] gestational age at birth, 39.3 [1.7] weeks) contributed 11 996 infant-quarters and 13 910 measurements of personal PM2.5 exposures (range, 5.4-1182.0 µg/m3). A total of 175 episodes of severe pneumonia were identified in 160 infants. Those with at least 1 episode of severe pneumonia had similar mean (SD) prenatal (101 [100] µg/m3 vs 88 [80] µg/m3; P = .11) and postnatal (70 [78] µg/m3 vs 67 [93] µg/m3; P = .68) PM2.5 exposures when compared with infants without severe pneumonia. There were no associations between prenatal (adjusted risk ratio [RR], 1.03; 95% CI, 0.94-1.13) or postnatal (adjusted RR, 0.97; 95% CI, 0.87-1.09) PM2.5 exposures and severe pneumonia or between CO exposures and severe pneumonia. Conclusions and Relevance:In this cohort study with exposure-response analysis, there was no evidence of an association between longitudinal PM2.5 or CO exposures and severe pneumonia in infants. Taken with the intention-to-treat analysis from the randomized clinical trial, these results challenge prior research suggesting that PM2.5 or CO exposures from biomass cooking are an important risk factor for severe pneumonia in infants.

Lead (Pb) and cadmium (Cd) are metals that occur naturally in the environment and are present in biomass fuels, such as wood. When these fuels are burned, they can release Pb and Cd into the air, leading to exposure through inhalation. Studies of exposure to metals and health outcomes suggest harmful impacts, including cardiovascular diseases. We assessed baseline associations between Pb and Cd concentrations in dried blood spots with systolic and diastolic blood pressure (SBP, DBP) among women in the Household Air Pollution Intervention Network (HAPIN) trial. We analyzed data from three of the four HAPIN randomized controlled trial sites (Guatemala, Peru, and Rwanda), focusing on women aged 40 to 79 years living in households reliant on biomass cooking. Dried blood spots were collected, processed, and analyzed for Pb and Cd exposure; SBP and DBP were measured following international guidelines. Demographic, socioeconomic, and dietary variables were collected via standardized questionnaires administered by local field staff. Statistical analyses included multivariable linear regression to examine associations between Pb and Cd, separately, and BP, adjusting for covariates informed by a Directed Acyclic Graph. Additional analyses assessed effect modification by age and research site. There was regional variation in BP levels among women, with median SBP and DBP values higher in Rwanda (116.3 mmHg, 73.0 mmHg) and Guatemala (113.3 mmHg, 68.3 mmHg) compared to Peru (106.0 mmHg, 63.3 mmHg). Pb exposure showed positive associations with both SBP and DBP. For each log-unit increase in Pb concentration, we observed increases of 2.36 mmHg SBP (95% CI 0.51, 4.20) and 1.42 mmHg DBP (95% CI 0.16, 2.67). Cd was not associated with SBP or DBP in this analysis. Pb exposure may be an important risk factor for increased SBP and DBP, markers of cardiovascular disease risk.

Background Air pollution may impair child growth and cognitive development, with potential markers including birth length and head circumference. Methods The Household Air Pollution Intervention Network (HAPIN) trial was an open label multi-country-randomized controlled trial, with 3200 pregnant women aged 18-34 years (9-19 weeks of gestation) randomly assigned in a 1:1 ratio to receive liquefied petroleum gas (LPG) stove intervention compared to women continuing to cook with solid fuels for 18 months. Particulate matter <= 2.5 mu m (PM2.5), black carbon (BC) and carbon monoxide (CO) 24-hour personal exposures were measured three times during pregnancy. Head circumference and length were measured < 24 h of birth. We conducted intention-to-treat and exposure-response analyses to determine the intervention effects and associations between household air pollution (HAP) exposure during pregnancy and head circumference, head circumference-for-gestational age Z-score, length, and length-for-gestational age Z-scores at birth. ClinicalTrials.gov. Results Between May 2018, and Feb 2020, 3200 pregnant women were randomly assigned to intervention (n = 1593) and control groups (n = 1607) with 3060 births included in the analysis. There was a 71.9 % reduction in PM2.5 in the intervention group with similar reductions for BC and CO. Intention-to-treat analysis showed that the intervention did not affect head circumference (beta = -0.01 cm, 95 %CI -0.11, 0.09), head circumference-for-gestational age Z-score (beta = -0.01, 95 %CI -0.08, 0.07), or birth length (beta = 0.14 cm, 95 %CI -0.01, 0.29) but did increase birth length-for-gestational age Z-score (beta = 0.09, 95 %CI 0.01, 0.16). After covariate adjustment, exposure-response analysis revealed that each log-unit increase in BC was associated with a decrease in birth length-for-gestational age Z-score (beta = -0.07, 95 %CI -0.13, -0.005). There was no evidence of hypothesized associations with PM2.5 or CO. Conclusion An LPG intervention reduced HAP exposure during pregnancy but had minor effects on birth length-for-gestational age Z-score. Birth length-for-gestational age was only associated with BC. Clinical Trial Registration: The study has been registered with ClinicalTrials.gov (Identifier NCT02944682).

Background:Household air pollution from biomass cookstoves is a major concern in low- and middle-income countries because it may be linked with increasing rates of metabolic disorders such as diabetes. We assessed cross-sectional associations between household air pollution concentrations and glycated hemoglobin (HbA1c) levels. Methods:We analyzed data from 346 women 40 to < 80 years of age who cooked with biomass fuel and were enrolled in the Household Air Pollution Intervention Network (HAPIN) Trial in Guatemala, India, Peru, and Rwanda. We explored associations of 24-h average personal exposure to fine particulate matter [PM ≤ 2.5 μ m in aerodynamic diameter ( PM 2.5 )], black carbon (BC), and carbon monoxide (CO) with HbA1c through individual pollutant linear models adjusted for potential confounders. We examined the effect modification of age, body mass index (BMI), and research site on the associations. Results:We did not observe evidence of associations between HbA1c (percentage points) and 1-unit increases in log-transformed PM 2.5 [ - 0.07 ; 95% confidence interval (CI): - 0.18 , 0.05], BC (0.01; 95% CI: - 0.15 , 0.13), or CO (0.07; 95% CI: - 0.24 , 0.10). Effect modification of the BC associations with HbA1c was observed for BMI and research site. An association in the hypothesized direction was observed among women with high BMI ( ≥ 25   kg / m 2 ): 0.13 (95% CI: - 0.06 , 0.31) compared with low BMI ( < 25   kg / m 2 ): - 0.17 (95% CI: - 0.38 , 0.04; p interaction = 0.04 ). In the Guatemala research site, there was an association in the hypothesized direction with HbA1c and log-transformed BC (0.36; 95% CI: 0.03, 0.70) that was countered by an association in the opposite direction as that hypothesized for the India site ( - 0.21 ; 95% CI: - 0.45 , 0.02) and associations consistent with the null association in the Peru and Rwanda sites ( p interaction = 0.05 ). No other evidence of effect modification was observed. Conclusions:Evidence suggests a need for further research to better understand household air pollution's influence on HbA1c, with particular attention on potential effect modifiers. https://doi.org/10.1289/JHP1053.

Traditional gravimetric instruments used for personal air pollution exposure measurements are often cumbersome and noisy and do not offer real‐time assessment capability. The Enhanced Children’s MicroPEM (ECM) is a comparatively lightweight and quiet instrument designed to capture both integrated filter‐based gravimetric samples and real‐time continuous (nephelometric) particulate matter with an aerodynamic diameter of 2.5 μm or less (PM2.5) concentrations. We assessed the performance and reliability of collocated ECMs in a subset of pregnant women participating in a randomized controlled trial in Guatemala to test a liquefied petroleum gas (LPG) cookstove (intervention) versus biomass (control) for cooking. We compared average daily (24 h) PM2.5 concentrations for the paired gravimetric (n = 219) and paired adjusted nephelometric (n = 221) samples using Spearman correlation and Bland–Altman agreement; we also assessed reliability based on the intraclass correlation coefficient (ICC) and root mean square error (RMSE). Median PM2.5 gravimetric concentrations were 93.5 μg/m3 (interquartile range (IQR) = 52.6–160.5) and 21.4 μg/m3 (IQR = 12.0–32.0) in the control and LPG intervention groups, respectively; the median adjusted nephelometric concentrations were 83.7 μg/m3 (IQR = 47.6–148.9) and 22.6 μg/m3 (IQR = 17.5–29.7) in the control and LPG groups, respectively. Spearman correlations were higher in the control arm (0.91) than in the LPG intervention arm (0.67) in the gravimetric comparisons. The same trend was observed for adjusted nephelometric measurements in the control (0.92) and intervention arms (0.75). ICC values were high in both gravimetric (0.93) and nephelometric (0.95) collocations. Small differences in RMSE were observed for the gravimetric (26.69 μg/m3) and nephelometric collocations (31.76 μg/m3). Our findings demonstrate strong reliability between collocated ECMs for both gravimetric and adjusted nephelometric PM2.5 personal exposure samples in rural Guatemala.Trial Registration: ClinicalTrials.gov identifier: NCT02944682

Background:Exposure to household air pollution from the combustion of solid fuels is a leading risk factor for death and disease in low- and middle-income countries, where cleaner cooking and lighting options are often unavailable. Few studies have measured personal exposure during pregnancy, a sensitive period of development, particularly in Africa. Objective:We aimed to characterize exposure during early to midpregnancy among women in Rwanda and to assess predictors of personal exposure, including stove and fuel type, cooking behaviors, housing conditions, sociodemographic characteristics, and other potential sources of exposure. Methods:We assessed 24-h baseline personal exposure data among 798 pregnant women in the Household Air Pollution Intervention Network (HAPIN) trial in Rwanda, including 717 with fine particulate matter ( PM 2.5 ), 569 with black carbon (BC), and 716 with carbon monoxide (CO) samples. Best subsets regression identified key predictors of personal PM 2.5 , BC, and CO exposure, defined by maximizing adjusted R 2 values and minimizing prediction errors (Mallow's CP and the Bayesian information criterion). Results:The 24-h median concentrations at baseline were 88.9   μ g / m 3 [ interquartile range  ( IQR ) = 85.0 ], 10.9   μ g   / m 3 ( IQR = 7.6), and 1.12  ppm ( IQR = 1.9) for PM 2.5 , BC, and CO, respectively. Households using kerosene as a primary lighting source had higher PM 2.5 levels ( median = 116   μ g / m 3 , IQR = 107) than those using electricity ( 64   μ g / m 3 , IQR = 69). Women in households with modified biomass stoves with a chimney had lower median values ( 48   μ g / m 3 , IQR = 52) for PM 2.5 , compared with those in households using open fires ( 113   μ g / m 3 , IQR = 74) and other traditional stove types ( 155   μ g / m 3 , IQR = 43) that yielded the highest values. Consensus models from the best subsets' regression explained 26% of the variation in PM 2.5 , 36% in BC, and 31% in CO concentrations. Conclusions:Based on a unique and large dataset describing personal exposure among pregnant women in rural Rwanda, lighting and cooking practices described some variability in household PM 2.5 concentrations, but overall, substantial unexplained variability remained. https://doi.org/10.1289/JHP1049.

Household air pollution from burning biomass materials, the main cooking fuel in low- and middle-income countries, may be linked to metabolic dysfunction. We assessed cross-sectional associations between household air pollution and body mass index (BMI), expecting to see increased BMI with higher pollution concentrations. We analyzed data from 414 women aged 40 to 79 years who resided in the households using biomass fuel and were enrolled in the multi-country Household Air Pollution Intervention Network (HAPIN) Trial. We explored associations of 24-h average personal exposure to fine particulate matter (PM2.5), black carbon (BC), and carbon monoxide (CO) with BMI through single pollutant linear and logistic models adjusted for potential confounders (i.e., age, socioeconomic indicators, education, dietary diversity, secondhand smoke exposure, alcohol and grain consumption).Sensitivity analyses explored air pollutants as quartiles, and other variables as potential confounders, such as physical activity, enrollment site, and dietary items. We examined effect modification of research site on the associations. We observed mixed evidence of associations between household air pollution and BMI in linear regression. There was no association with BMI and PM₂.₅ (1-unit increase in log-transformed PM₂.₅ estimate 0.02 kg/m2 [95

Exposure to metals from the combustion of biomass via inhalation may result in negative health outcomes affecting a variety of organs and systems. Pregnant women cooking with biomass fuels may be exposed to metals, such as lead (Pb) and cadmium (Cd), and have unique risks for adverse health effects with potential impacts on the growing fetus. We assessed the associations between household air pollution and metals detected in dried blood spots from pregnant women at baseline in Rwanda. We analyzed data from 781 pregnant women aged 18–35 years who resided in rural households using biomass fuel and who were enrolled in the Household Air Pollution Intervention Network (HAPIN) Trial in Rwanda. We explored associations between 24-h average natural log-transformed personal exposures to fine particulate matter (PM2.5), black carbon (BC), and carbon monoxide (CO) and K + standardized Pb and Cd concentrations using linear regression models adjusted for potential confounders (i.e., age, body mass index, bicycle ownership, fish consumption, and food insecurity). The adjusted models showed positive but non-significant associations between air pollutant concentrations and metals detected in blood: PM₂.₅ and Pb (β coefficient: 0.06; 95

Background Household air pollution (HAP) is a leading environmental risk factor accounting for about 1.6 million premature deaths mainly in low- and middle-income countries (LMICs). However, no multicounty randomized controlled trials have assessed the effect of liquefied petroleum gas (LPG) stove intervention on HAP and maternal and child health outcomes. The Household Air Pollution Intervention Network (HAPIN) was the first to assess this by implementing a common protocol in four LMICs. Objective This manuscript describes the implementation of the HAPIN data management protocol via Research Electronic Data Capture (REDCap) used to collect over 50 million data points in more than 4000 variables from 80 case report forms (CRFs). Methods We recruited 800 pregnant women in each study country (Guatemala, India, Peru, and Rwanda) who used biomass fuels in their households. Households were randomly assigned to receive LPG stoves and 18 months of free LPG supply (intervention) or to continue using biomass fuels (control). Households were followed for 18 months and assessed for primary health outcomes: low birth weight, severe pneumonia, and stunting. The HAPIN Data Management Core (DMC) implemented identical REDCap projects for each study site using shared variable names and timelines in local languages. Field staff collected data offline using tablets on the REDCap Mobile Application. Results Utilizing the REDCap application allowed the HAPIN DMC to collect and store data securely, access data (near real-time), create reports, perform quality control, update questionnaires, and provide timely feedback to local data management teams. Additional REDCap functionalities (e.g. scheduling, data validation, and barcode scanning) supported the study. Conclusions While the HAPIN trial experienced some challenges, REDCap effectively met HAPIN study goals, including quality data collection and timely reporting and analysis on this important global health trial, and supported more than 40 peer-reviewed scientific publications to date.

BACKGROUND:Household air pollution might lead to fetal growth restriction during pregnancy. We aimed to investigate whether a liquefied petroleum gas (LPG) intervention to reduce personal exposures to household air pollution during pregnancy would alter fetal growth. METHODS:The Household Air Pollution Intervention Network (HAPIN) trial was an open-label randomised controlled trial conducted in ten resource-limited settings across Guatemala, India, Peru, and Rwanda. Pregnant women aged 18-34 years (9-19 weeks of gestation) were randomly assigned in a 1:1 ratio to receive an LPG stove, continuous fuel delivery, and behavioural messaging or to continue usual cooking with biomass for 18 months. We conducted ultrasound assessments at baseline, 24-28 weeks of gestation (the first pregnancy visit), and 32-36 weeks of gestation (the second pregnancy visit), to measure fetal size; we monitored 24 h personal exposures to household air pollutants during these visits; and we weighed children at birth. We conducted intention-to-treat analyses to estimate differences in fetal size between the intervention and control group, and exposure-response analyses to identify associations between household air pollutants and fetal size. This trial is registered with ClinicalTrials.gov (NCT02944682). FINDINGS:Between May 7, 2018, and Feb 29, 2020, we randomly assigned 3200 pregnant women (1593 to the intervention group and 1607 to the control group). The mean gestational age was 14·5 (SD 3·0) weeks and mean maternal age was 25·6 (4·5) years. We obtained ultrasound assessments in 3147 (98·3%) women at baseline, 3052 (95·4%) women at the first pregnancy visit, and 2962 (92·6%) at the second pregnancy visit, through to Aug 25, 2020. Intervention adherence was high (the median proportion of days with biomass stove use was 0·0%, IQR 0·0-1·6) and pregnant women in the intervention group had lower mean exposures to particulate matter with a diameter less than 2·5 μm (PM2·5; 35·0 [SD 37·2] μg/m3vs 103·3 [97·9] μg/m3) than did women in the control group. We did not find differences in averaged post-randomisation Z scores for head circumference (0·30 vs 0·39; p=0·04), abdominal circumference (0·38 vs 0·39; p=0·99), femur length (0·44 vs 0·45; p=0·73), and estimated fetal weight or birthweight (-0·13 vs -0·12; p=0·70) between the intervention and control groups. Personal exposures to household air pollutants were not associated with fetal size. INTERPRETATION:Although an LPG cooking intervention successfully reduced personal exposure to air pollution during pregnancy, it did not affect fetal size. Our findings do not support the use of unvented liquefied petroleum gas stoves as a strategy to increase fetal growth in settings were biomass fuels are used predominantly for cooking. FUNDING:US National Institutes of Health and Bill & Melinda Gates Foundation. TRANSLATIONS:For the Kinyarwanda, Spanish and Tamil translations of the abstract see Supplementary Materials section.

BackgroundHousehold air pollution is associated with stunted growth in infants. Whether the replacement of biomass fuel (e.g., wood, dung, or agricultural crop waste) with liquefied petroleum gas (LPG) for cooking can reduce the risk of stunting is unknown.MethodsWe conducted a randomized trial involving 3200 pregnant women 18 to 34 years of age in four low- and middle-income countries. Women at 9 to less than 20 weeks' gestation were randomly assigned to use a free LPG cookstove with continuous free fuel delivery for 18 months (intervention group) or to continue using a biomass cookstove (control group). The length of each infant was measured at 12 months of age, and personal exposures to fine particulate matter (particles with an aerodynamic diameter of <= 2.5 mu m) were monitored starting at pregnancy and continuing until the infants were 1 year of age. The primary outcome for which data are presented in the current report - stunting (defined as a length-for-age z score that was more than two standard deviations below the median of a growth standard) at 12 months of age - was one of four primary outcomes of the trial. Intention-to-treat analyses were performed to estimate the relative risk of stunting.ResultsAdherence to the intervention was high, and the intervention resulted in lower prenatal and postnatal 24-hour personal exposures to fine particulate matter than the control (mean prenatal exposure, 35.0 mu g per cubic meter vs. 103.3 mu g per cubic meter; mean postnatal exposure, 37.9 mu g per cubic meter vs. 109.2 mu g per cubic meter). Among 3061 live births, 1171 (76.2%) of the 1536 infants born to women in the intervention group and 1186 (77.8%) of the 1525 infants born to women in the control group had a valid length measurement at 12 months of age. Stunting occurred in 321 of the 1171 infants included in the analysis (27.4%) of the infants born to women in the intervention group and in 299 of the 1186 infants included in the analysis (25.2%) of those born to women in the control group (relative risk, 1.10; 98.75% confidence interval, 0.94 to 1.29; P=0.12).ConclusionsAn intervention strategy starting in pregnancy and aimed at mitigating household air pollution by replacing biomass fuel with LPG for cooking did not reduce the risk of stunting in infants. (Funded by the National Institutes of Health and the Bill and Melinda Gates Foundation; HAPIN ClinicalTrials.gov number, NCT02944682.) In a randomized trial involving pregnant women in low- and middle-income countries, the use of LPG stoves in place of biomass stoves did not result in a lower risk of stunting in offspring, despite lower levels of household air pollutants.

BACKGROUND:Relatively clean cooking fuels such as liquefied petroleum gas (LPG) emit less fine particulate matter (PM2·5) and carbon monoxide (CO) than polluting fuels (eg, wood, charcoal). Yet, some clean cooking interventions have not achieved substantial exposure reductions. This study evaluates determinants of between-community variability in exposures to household air pollution (HAP) across sub-Saharan Africa. METHODS:In this measurement study, we recruited households cooking primarily with LPG or exclusively with wood or charcoal in peri-urban Cameroon, Ghana, and Kenya from previously surveyed households. In 2019-20, we conducted monitoring of 24 h PM2·5 and CO kitchen concentrations (n=256) and female cook (n=248) and child (n=124) exposures. PM2·5 measurements used gravimetric and light scattering methods. Stove use monitoring and surveys on cooking characteristics and ambient air pollution exposure (eg, walking time to main road) were also administered. FINDINGS:The mean PM2·5 kitchen concentration was five times higher among households cooking with charcoal than those using LPG in the Kenyan community (297 μg/m3, 95% CI 216-406, vs 61 μg/m3, 49-76), but only 4 μg/m3 higher in the Ghanaian community (56 μg/m3, 45-70, vs 52 μg/m3, 40-68). The mean CO kitchen concentration in charcoal-using households was double the WHO guideline (6·11 parts per million [ppm]) in the Kenyan community (15·81 ppm, 95% CI 8·71-28·72), but below the guideline in the Ghanaian setting (1·77 ppm, 1·04-2·99). In all communities, mean PM2·5 cook exposures only met the WHO interim-1 target (35 μg/m3) among LPG users staying indoors and living more than 10 min walk from a road. INTERPRETATION:Community-level variation in the relative difference in HAP exposures between LPG and polluting cooking fuel users in peri-urban sub-Saharan Africa might be attributed to differences in ambient air pollution levels. Thus, mitigation of indoor and outdoor PM2·5 sources will probably be critical for obtaining significant exposure reductions in rapidly urbanising settings of sub-Saharan Africa. FUNDING:UK National Institute for Health and Care Research.