Globally, nearly 3 billion people rely on solid fuels for cooking and heating, the vast majority in low- and middle-income countries (LMICs). The resulting household air pollution (HAP) is the third leading risk factor in the 2010 global burden of disease, accounting for an estimated 4.3 million deaths annually, largely among women and young children. While cleaner fuels reduce HAP and seemingly increase birthweight, reduce childhood pneumonia incidence and stunting, and lower blood pressure in adults, robust evidence for any health benefits is lacking. Previous interventions have provided cleaner biomass-based cookstoves, but have failed to reduce exposure to levels that produce important health improvements. There have been no large-scale field trials with liquefied petroleum gas (LPG) cookstoves, likely the cleanest scalable intervention.
To conduct a randomized controlled trial of LPG stove and fuel distribution in 3,200 households in four diverse LMICs to deliver rigorous evidence regarding potential health benefits across the lifespan.
Using an intent-to-treat analysis, determine the effect of a randomized LPG stove and fuel intervention on health in four diverse LMIC populations using a common protocol.
- Compared to control households with biomass cookstoves (400/site), pregnant women in households that receive LPG stoves and fuel (400/site) will have offspring with increased birthweight, reduced pneumonia incidence and improved growth (length-for-age/stunting) up to age 2 years (primary outcomes); and decreased preterm birth and improved gross motor development up to age 2 years (secondary outcomes).
- Compared to control households with biomass cookstoves (100/site), older adult women (35-64 years) in households that receive LPG stoves and fuel (100/site) will have reduced blood pressure (primary outcome); improved endothelial function, decreased carotid intima-media thickness, and less respiratory health impairment and improved quality of life as measured by the St. George Respiratory Questionnaire and the Short Form 36, respectively (secondary outcomes), during the 30-month follow up period. Quality-adjusted life years saved from the intervention will be calculated to determine cost effectiveness.
Determine the exposure-response curves for HAP and health in four diverse LMIC populations.
Using repeated 48-hour exposure measurements, establish an exposure-response curve for all primary and secondary outcomes (assessing potential non-linearity), while adjusting for confounders. Determine which pollutants are better predictors of different outcomes. Conduct sensitivity analyses via restriction to intervention or control groups; and, use of state-of-the-art causal inference techniques as a novel approach to the analysis of exposure-response relationships. While evidence for an overall effect of the intervention is available from Aim 1, analysis of exposure-response is critical for quantitative risk assessment and policy determinations of acceptable levels of HAP regardless of cooking technology.
Determine relationships between LPG intervention and biomarkers of exposure/health effects.
- The Biomarker Center will conduct both targeted and exploratory (metabolomics) analyses.
- Hypothesis: Participants residing in households that receive LPG stoves will have lower carcinogen metabolites (urinary polycyclic aromatic hydrocarbons and volatile organic carbons) and endothelial, inflammatory, and oxidative stress biomarkers (e.g., ICAM-1, VCAM-1, endothelin-1, E-selectin, CRP, IL-6 among others) when compared to women in control households.
Thomas Clasen, Emory University
- National Institutes of Health, United States
- National Heart, Lung, and Blood Institute, United States
- National Institute of Environmental Health Sciences, United States
- National Institute of Child Health and Human Development, United States
- National Cancer Institute, United States
- Bill & Melinda Gates Foundation, United States