Household Air Pollution Interventions to Improve Health in Low- and Middle-Income Countries: An Official American Thoracic Society Research Statement.

Background: An estimated 3 billion people, largely in low- and middle-income countries, rely on unclean fuels for cooking, heating, and lighting to meet household energy needs. The resulting exposure to household air pollution (HAP) is a leading cause of pneumonia, chronic lung disease, and other adverse health effects. In the last decade, randomized controlled trials of clean cooking interventions to reduce HAP have been conducted. We aim to provide guidance on how to interpret the findings of these trials and how they should inform policy makers and practitioners.Methods: We assembled a multidisciplinary working group of international researchers, public health practitioners, and policymakers with expertise in household air pollution from within academia, the American Thoracic Society, funders, nongovernmental organizations, and global organizations, including the World Bank and the World Health Organization. We performed a literature search, convened four sessions via web conference, and developed consensus conclusions and recommendations via the Delphi method.Results: The committee reached consensus on 14 conclusions and recommendations. Although some trials using cleaner-burning biomass stoves or cleaner-cooking fuels have reduced HAP exposure, the committee was divided (with 55% saying no and 45% saying yes) on whether the studied interventions improved measured health outcomes.Conclusions: HAP is associated with adverse health effects in observational studies. However, it remains unclear which household energy interventions reduce exposure, improve health, can be scaled, and are sustainable. Researchers should engage with policy makers and practitioners working to scale cleaner energy solutions to understand and address their information needs.

A global review of the state of the evidence of household air pollution's contribution to ambient fine particulate matter and their related health impacts.

Direct exposure to household fine particulate air pollution (HAP) associated with inefficient combustion of fuels (wood, charcoal, coal, crop residues, kerosene, etc.) for cooking, space-heating, and lighting is estimated to result in 2.3 (1.6-3.1) million premature yearly deaths globally. HAP emitted indoors escapes outdoors and is a leading source of outdoor ambient fine particulate air pollution (AAP) in low- and middle-income countries, often being a larger contributor than well-recognized sources including road transport, industry, coal-fired power plants, brick kilns, and construction dust. We review published scientific studies that model the contribution of HAP to AAP at global and major sub-regional scales. We describe strengths and limitations of the current state of knowledge on HAP's contribution to AAP and the related impact on public health and provide recommendations to improve these estimates. We find that HAP is a dominant source of ambient fine particulate matter (PM2.5) globally - regardless of variations in model types, configurations, and emission inventories used - that contributes approximately 20 % of total global PM2.5 exposure. There are large regional variations: in South Asia, HAP contributes âˆ¼ 30 % of ambient PM2.5, while in high-income North America the fraction is âˆ¼ 7 %. The median estimate indicates that the household contribution to ambient air pollution results in a substantial premature mortality burden globally of about 0.77(0.54-1) million excess deaths, in addition to the 2.3 (1.6-3.1) million deaths from direct HAP exposure. Coordinated global action is required to avert this burden.

Impact of prenatal maternal psychological distress on fetal biometric parameters in household air pollution-exposed Nigerian women.

RATIONALE: Studies identify prenatal household air pollution (HAP) exposure and maternal psychological distress (PMPD) as independent factors contributing to gestational ill-health and adverse birth outcomes. OBJECTIVE: We investigated the impact of PMPD on fetal biometric parameters (FBP) in HAP-exposed pregnant Nigerian women. METHODS: The randomized controlled trial (RCT; ClinicalTrials.gov NCT02394574) investigated effects of HAP exposure in pregnant Nigerian women (n = 324), who customarily cooked with polluting fuels (firewood or kerosene). Half of the women (intervention group) were given CleanCook ethanol stoves to use for 156 days during the study. Once a month, all women were administered an abridged version of the SF-12v2TM health-related quality of life questionnaire to assess psychological distress. Using mixed effects linear regression models, adjusted for relevant covariates, we analyzed associations between the women's exposure to PM2·5 (particulate matter with an aerodynamic diameter<2·5 microns) from HAP, their PMPD scores, and FBP (ultrasound estimated fetal weight [UEFW], head circumference [HC], abdominal circumference [AC], femur length [FL], biparietal diameter [BPD], estimated gestational age [GA] and intrauterine growth restriction [IUGR]), and birth anthropometric measures (birth weight [BW] and birth length [BL]). RESULTS: PMPD negatively impacted UEFW, HC, FL, BPD and BL (p<0·05). Controls (kerosene/firewood users) experienced significantly higher PMPD compared with ethanol-stove users (p<0·05). The mediation analysis revealed that the proportion of the outcome (fetal biometrics, birth anthropometrics, IUGR and GA), which can be explained via PMPD by groups (intervention vs. control) after adjusting for confounding variables was 6·2% (0·062). No significant correlation was observed between levels of PM2.5 exposure and PMPD scores. CONCLUSIONS: PMPD was an independent mediator of adverse fetal biometric parameters in pregnant women, who were exposed to HAP from burning of firewood/kerosene. Formulating preventative measures to alleviate maternal distress during pregnancy and reducing exposure to HAP is important from public health perspectives.

Household air pollution, ultrasound measurement, fetal biometric parameters and intrauterine growth restriction.

BACKGROUND: Low birthweight, intrauterine growth restriction (IUGR) and perinatal mortality have been associated with air pollution. However, intervention studies that use ultrasound measurements to assess the effects of household air pollution (HAP) on fetal biometric parameters (FBP) are rare. We investigated the effect of a cookstove intervention on FBP and IUGR in a randomized controlled trial (RCT) cohort of HAP-exposed pregnant Nigerian women. METHODS: We recruited 324 women early in the second trimester of pregnancy. Between 16 and 18 weeks, we randomized them to either continue cooking with firewood/kerosene (control group) or receive a CleanCook stove and ethanol fuel (intervention group). We measured fetal biparietal diameter (BPD), head circumference (HC), femur length (FL), abdominal circumference (AC) and ultrasound-estimated fetal weight (U-EFW) in the second and third trimesters. The women were clinically followed up at six regular time points during their pregnancies. Once during the women's second trimester and once during the third, we made 72-h continuous measurements of their personal exposures to particulate matter having aerodynamic diameter < 2.5 µm (PM2.5). We adopted a modified intent-to-treat approach for the analysis. Differences between the intervention and control groups on impact of HAP on fetal growth trajectories were analyzed using mixed effects regression models. RESULTS: There were no significant differences in fetal growth trajectories between the intervention and control groups. CONCLUSIONS: Larger studies in a setting of low ambient air pollution are required to further investigate the effect of transitioning to a cleaner fuel such as ethanol on intrauterine growth. TRIAL REGISTRATION: ClinicalTrials.gov NCT02394574 ; September 2012.

Household air pollution and chronic hypoxia in the placenta of pregnant Nigerian women: A randomized controlled ethanol Cookstove intervention.

BACKGROUND: Household air pollution (HAP) is associated with adverse pregnancy outcomes. OBJECTIVES: Investigate impact of in-utero HAP exposure on placental development and chronic hypoxia. METHODS: Markers of chronic placental hypoxia [Hofbauer cells (HBC), syncytial knots (SK), chorionic vascular density (cVD) and hypoxia-inducible factor (HIF)] were stained by hematoxylin-eosin and/or immunohistochemically in placenta samples collected from firewood-/kerosene-users (A,n=16), and ethanol-users (B,n=20) that participated in a randomized controlled intervention trial in Ibadan, Nigeria. A third group of non-smoking and presumed natural gas-using Chicago women (C,n=12) were included in this exploratory pilot to assess for possible differences in placenta histology between similar racial groups. All patients had uncomplicated pregnancies and delivered at term. RESULTS: HBC, SK and cVD were significantly increased among firewood-/kerosene-users compared to ethanol-users and natural gas-using Chicago women (HBC medians 5.5, 3.5, and 2.0, respectively; SK means 55.6, 41.8 and 30.1; cVD means 8.8, 6.2, and 5.2; all p<0.01). HIF expression was significantly higher in Group A compared to B and C (all p<0.001). CONCLUSIONS: In-utero exposure to HAP is associated with pathologic changes and HIF expression consistent with chronic hypoxia in placenta of firewood/kerosene-users compared to ethanol-users with less HAP exposure and Chicago women with no presumed HAP exposure. Presence of chronic hypoxic signature in placenta of women exposed to HAP has implications for adverse pregnancy complications and future growth and development of the young children. Future larger studies need to focus on HAP exposure and placental disorders like preeclampsia and long-term health impact of in-utero exposure to HAP.

Pregnancy outcomes and ethanol cook stove intervention: A randomized-controlled trial in Ibadan, Nigeria.

BACKGROUND: Household air pollution (HAP) exposure has been linked to adverse pregnancy outcomes. OBJECTIVES: A randomized controlled trial was undertaken in Ibadan, Nigeria to determine the impact of cooking with ethanol on pregnancy outcomes. METHODS: Three-hundred-twenty-four pregnant women were randomized to either the control (continued cooking using kerosene/firewood stove, n=162) or intervention group (received ethanol stove, n=162). Primary outcome variables were birthweight, preterm delivery, intrauterine growth restriction (IUGR), and occurrence of miscarriage/stillbirth. RESULTS: Mean birthweights for ethanol and controls were 3076 and 2988g, respectively; the difference, 88g, (95% confidence interval: -18g to 194g), was not statistically significant (p=0.10). After adjusting for covariates, the difference reached significance (p=0.020). Rates of preterm delivery were 6.7% (ethanol) and 11.0% (control), (p=0.22). Number of miscarriages was 1(ethanol) vs. 4 (control) and stillbirths was 3 (ethanol) vs. 7 (control) (both non-significant). Average gestational age at delivery was significantly (p=0.015) higher in ethanol-users (39.2weeks) compared to controls (38.2weeks). Perinatal mortality (stillbirths and neonatal deaths) was twice as high in controls compared to ethanol-users (7.9% vs. 3.9%; p=0.045, after adjustment for covariates). We did not detect significant differences in exposure levels between the two treatment arms, perhaps due to large seasonal effects and high ambient air pollution levels. CONCLUSIONS: Transition from traditional biomass/kerosene fuel to ethanol reduced adverse pregnancy outcomes. However, the difference in birthweight was statistically significant only after covariate adjustment and the other significant differences were in tertiary endpoints. Our results are suggestive of a beneficial effect of ethanol use. Larger trials are required to validate these findings.

Household air pollution and angiogenic factors in pregnant Nigerian women: A randomized controlled ethanol cookstove intervention.

BACKGROUND: Maternal exposure to ambient air pollution affects placental growth markers. OBJECTIVES: Investigate impact of household air pollution (HAP) on placental growth markers. METHODS: Two groups of pregnant women were identified: firewood/kerosene stove-users (A, n=33) and bioethanol stove-users (B, n=44) that participated in a randomized control trial in Ibadan, Nigeria. A third group of non-smoking and presumed liquefied petroleum gas-using Chicago women (C, n=19) were included in this exploratory pilot to assess for possible differences between similar racial groups. Levels of placental growth factor (PlGF) and soluble fms-like tyrosine kinase 1 (sFlt-1) were measured in maternal and cord plasma using ELISA. RESULTS: Maternal and cord blood sFlt-1 and PlGF did not differ significantly between women of groups A and B. Nevertheless, both groups differed significantly from the Chicago group in that group A women had lower maternal sFlt-1 (1372.50 vs. 3194.19) but higher PlGF (1607.87 vs. 442.80), and higher cord blood sFlt-1 (2925.02 vs. 107.53) and PlGF (223.68 vs. 6.92), all p≤0.001. Group B showed similar trends (all p≤0.002). Maternal PlGF levels were positively correlated to minutes of HAP exposure when PM2.5 concentration was above 100µg/m3 in Nigerian women. CONCLUSIONS: Maternal levels of PlGF and cord blood levels of sFlt-1 and PlGF in Nigerian women with varying HAP exposures were significantly higher than Chicago-based women who had no presumed HAP exposure. It suggests that in-utero exposure to HAP influenced levels of angiogenic factors involved in normal placentation and growth and could represent compensation for pollutants exposure to preserve fetal viability.

Randomized Controlled Ethanol Cookstove Intervention and Blood Pressure in Pregnant Nigerian Women.

RATIONALE: Hypertension during pregnancy is a leading cause of maternal mortality. Exposure to household air pollution elevates blood pressure (BP). OBJECTIVES: To investigate the ability of a clean cookstove intervention to lower BP during pregnancy. METHODS: We conducted a randomized controlled trial in Nigeria. Pregnant women cooking with kerosene or firewood were randomly assigned to an ethanol arm (n = 162) or a control arm (n = 162). BP measurements were taken during six antenatal visits. In the primary analysis, we compared ethanol users with control subjects. In subgroup analyses, we compared baseline kerosene users assigned to the intervention with kerosene control subjects and compared baseline firewood users assigned to ethanol with firewood control subjects. MEASUREMENTS AND MAIN RESULTS: The change in diastolic blood pressure (DBP) over time was significantly different between ethanol users and control subjects (P = 0.040); systolic blood pressure (SBP) did not differ (P = 0.86). In subgroup analyses, there was no significant intervention effect for SBP; a significant difference for DBP (P = 0.031) existed among preintervention kerosene users. At the last visit, mean DBP was 2.8 mm Hg higher in control subjects than in ethanol users (3.6 mm Hg greater in control subjects than in ethanol users among preintervention kerosene users), and 6.4% of control subjects were hypertensive (SBP ≥140 and/or DBP ≥90 mm Hg) versus 1.9% of ethanol users (P = 0.051). Among preintervention kerosene users, 8.8% of control subjects were hypertensive compared with 1.8% of ethanol users (P = 0.029). CONCLUSIONS: To our knowledge, this is the first cookstove randomized controlled trial examining prenatal BP. Ethanol cookstoves have potential to reduce DBP and hypertension during pregnancy. Accordingly, clean cooking fuels may reduce adverse health impacts associated with household air pollution. Clinical trial registered with www.clinicaltrials.gov (NCT02394574).

Effect of a clean stove intervention on inflammatory biomarkers in pregnant women in Ibadan, Nigeria: A randomized controlled study.

BACKGROUND: Exposure to household air pollution (HAP) has been linked to systemic inflammation. We determined the impact of transition from traditional firewood/kerosene stove to bioethanol-burning stove on inflammatory biomarkers in pregnant Nigerian women. METHODS: Women (n=324), cooking with kerosene/firewood, were recruited during their first trimester of pregnancy from June 2013-October 2015 and were randomly allocated to either control (n=162) or intervention (n=162) group using web-based randomization. Controls continued to use their own firewood/kerosene stove, while intervention participants received bioethanol CleanCook stoves. Serum concentrations of retinol-binding protein (RBP), malondialdehyde (MDA), tumor necrosis factor alpha (TNF)-α, interleukin (IL)-6, and IL-8 were measured by ELISA. RESULTS: After excluding 53 women (loss of follow-up, untimely biomarker assessments, incorrect dates of enrollment), data from 271 women were included in analysis. Mean (SD) change in RBP, MDA, TNF-α, IL-6, and IL-8 between baseline and third trimester was -2.16 (4.47), -19.6 (46.4), 3.72 (37.2), 0.51 (14.4), and 13.2 (197), respectively, in intervention and -2.25 (4.30), -24.6 (43.6), 7.17 (32.6), -1.79, (11.4), and 31.3 (296) in control groups. None of these changes differed significantly between the two treatment arms. However, changes from baseline in TNF-α levels were significantly different between intervention and control groups in subset of women (n=99) using firewood before trial (-7.03 [32.9] vs. +12.4 [33.6]; 95% CI for group difference: -35.4 to -3.4, p=0.018). CONCLUSIONS: Decrease in TNF-α concentration from baseline to third trimesters in intervention group women could indicate reduced cardiovascular stress and prothrombotic effects from decreased HAP. Our findings suggest that ethanol-burning stoves may mitigate cardiovascular health risks.

Ventilated cookstoves associated with improvements in respiratory health-related quality of life in rural Bolivia.

BACKGROUND: Household air pollution (HAP) from combustion of biomass fuels worldwide is linked to asthma, respiratory infections and chronic pulmonary diseases. Implementation of ventilated cookstoves significantly reduces exposure to HAP. However, improvements in concurrent respiratory health-related quality of life (HRQoL) have not been previously evaluated with a standardized questionnaire. METHODS: The association between woodsmoke exposure and respiratory HRQoL outcomes was evaluated using an intervention study in a rural community in Bolivia. Indoor carbon monoxide (CO) levels from traditional stoves and from cookstoves with chimneys were analyzed alongside interview results of women heads-of-households using the St. George's Respiratory Questionnaire (SGRQ) in 2009 and 1-year post-intervention. RESULTS: Pronounced improvements in respiratory HRQoL and significant reductions of household CO levels followed installation of ventilated cookstoves. Stove implementation yielded lower indoor CO values and correlated positively with improved SGRQ scores. CONCLUSIONS: This is the first use of a standardized respiratory HRQoL assessment to determine the impact of ventilated cookstove implementation on reducing HAP. This preliminary study utilizes the SGRQ as a valuable tool enabling analysis of these health effects in relation to other respiratory disease states.