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

Abstract

Background: Exposure to ${\mathrm{PM}}_{2.5}$ arising from solid fuel combustion is estimated to result in $\sim 2.3$ 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 ${\mathrm{PM}}_{2.5}$, carbon monoxide (CO), and black carbon (BC) were measured for pregnant women once before randomization into control ($n=\mathrm{1,605}$) and LPG ($n=\mathrm{1,590}$) 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 $\le 2.5\mu m$ (${\mathrm{PM}}_{2.5}$) in the intervention arm were lower by 66% at the first (71.5 vs. $24.1{\mu g/m}^3$), and second follow-up visits (69.5 vs. $23.7{\mu g/m}^3$) compared to controls. BC exposures were lower in the intervention arm by 72% (9.7 vs. $2.7{\mu g/m}^3$) and 70% (9.6 vs. $2.8{\mu g/m}^3$) at the first and second follow-up visits, respectively, and carbon monoxide exposure was 82% lower at both visits (1.1 vs. $0.2\text{ppm}$) in comparison with controls. Exposure reductions were consistent over time and were similar across research locations.

Discussion: Postintervention ${\mathrm{PM}}_{2.5}$ 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 ${\mathrm{PM}}_{2.5}$ samples falling below the World Health Organization Annual Interim Target 1 of $35{\mu g/m}^3$. This study indicates that an LPG intervention can reduce ${\mathrm{PM}}_{2.5}$ exposures to levels at or below WHO targets. https://doi.org/10.1289/EHP10295.

Trial registration: ClinicalTrials.gov NCT02944682.