Exposure Contrasts of Pregnant Women during the Household Air Pollution Intervention Network Randomized Controlled Trial

BACKGROUND: Exposure to PM2:5 arising from solid fuel combustion is estimated to result in ∼ 2:3 million premature deaths and 91 million lost disability-adjusted life years annually. Interventions attempting to mitigate this burden have had limited success in reducing exposures to levels thought to provide substantive health benefits. OBJECTIVES: This paper reports exposure reductions achieved by a liquified petroleum gas (LPG) stove and fuel intervention for pregnant mothers in the Household Air Pollution Intervention Network (HAPIN) randomized controlled trial. METHODS: The HAPIN trial included 3,195 households primarily using biomass for cooking in Guatemala, India, Peru, and Rwanda. Twenty-four-hour exposures to PM2:5, carbon monoxide (CO), and black carbon (BC) were measured for pregnant women once before randomization into control (n = 1,605) and LPG (n = 1,590) arms and twice thereafter (aligned with trimester). Changes in exposure were estimated by directly comparing exposures between intervention and control arms and by using linear mixed-effect models to estimate the impact of the intervention on exposure levels. RESULTS: Median postrandomization exposures of particulate matter (PM) with aerodynamic diameter ≤2:5 lm (PM2:5) in the intervention arm were lower by 66% at the first (71.5 vs. 24:1 lg=m3), and second follow-up visits (69.5 vs. 23:7 lg=m3) compared to controls. BC exposures were lower in the intervention arm by 72% (9.7 vs. 2:7 lg=m3) and 70% (9.6 vs. 2:8 lg=m3) at the first and second follow-up visits, respectively, and carbon monoxide exposure was 82% lower at both visits (1.1 vs. 0:2 ppm) in comparison with controls. Exposure reductions were consistent over time and were similar across research locations. DISCUSSION: Postintervention PM2:5 exposures in the intervention arm were at the lower end of what has been reported for LPG and other clean fuel interventions, with 69% of PM2:5 samples falling below the World Health Organization Annual Interim Target 1 of 35 lg=m3 . This study indicates that an LPG intervention can reduce PM2:5 exposures to levels at or below WHO targets.