LPG stove and fuel intervention among pregnant women reduce fine particle air pollution exposures in three countries: Pilot results from the HAPIN trial

Abstract

The Household Air Pollution Intervention Network trial is a multi-country study on the effects of a liquefied petroleum gas (LPG) stove and fuel distribution intervention on women's and children's health. There is limited data on exposure reductions achieved by switching from solid to clean cooking fuels in rural settings across multiple countries. As formative research in 2017, we recruited pregnant women and characterized the impact of the intervention on personal exposures and kitchen levels of fine particulate matter (PM 2.5 ) in Guatemala, India, and Rwanda. Forty pregnant women were enrolled in each site. We measured cooking area concentrations of and personal exposures to PM 2.5 for 24 or 48 h using gravimetric-based PM 2.5 samplers at baseline and two follow-ups over two months after delivery of an LPG cookstove and free fuel supply. Mixed models were used to estimate PM 2.5 reductions. Median kitchen PM 2.5 concentrations were 296 μg/m 3 at baseline (interquartile range, IQR: 158–507), 24 μg/m 3 at first follow-up (IQR: 18–37), and 23 μg/m 3 at second follow-up (IQR: 14–37). Median personal exposures to PM 2.5 were 134 μg/m 3 at baseline (IQR: 71–224), 35 μg/m 3 at first follow-up (IQR: 23–51), and 32 μg/m 3 at second follow-up (IQR: 23–47). Overall, the LPG intervention was associated with a 92% (95% confidence interval (CI): 90–94%) reduction in kitchen PM 2.5 concentrations and a 74% (95% CI: 70–79%) reduction in personal PM 2.5 exposures. Results were similar for each site. Conclusions The intervention was associated with substantial reductions in kitchen and personal PM 2.5 overall and in all sites. Results suggest LPG interventions in these rural settings may lower exposures to the WHO annual interim target-1 of 35 μg/m 3 . The range of exposure contrasts falls on steep sections of estimated exposure-response curves for birthweight, blood pressure, and acute lower respiratory infections, implying potentially important health benefits when transitioning from solid fuels to LPG.

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

“… 18 – 21 Briefly, IRCs were located in relatively low-density rural areas that had low background air pollution concentrations according to 24- to 48-h ambient outdoor measurements, as well as minimal observation of other pollution sources. 17 , 22 , 23 Study locations were selected in areas where most households typically used traditional biomass stoves to fulfill their cooking and energy needs. Within each IRC, specific study sites were chosen during a 12-month period of formative research.…”

“…Intervention components were informed by formative research and described in detail previously. 21 , 22 The stoves and fuel cylinders were procured separately at each IRC following formative research on local cooking practices and equipment availability. Stove design varied by site, but all stoves had at least two burners and included additional components for preparation of traditional foods (e.g., a flat griddle for cooking tortillas in Guatemala and a roasting grill in Rwanda).…”

Exposure–response relationships for personal exposure to fine particulate matter (PM2·5), carbon monoxide, and black carbon and birthweight: Results from the multi-country Household Air Pollution Intervention Network (HAPIN) trial

“…The HAP exposure levels associated with biomass use (such as at baseline and in the control arm) in our study are at the lower end of what has been reported in previous trials, with the possible exception of the GRAPHS trial. Based on pilot phase exposure reductions 20,21 and estimated supra-linear E-R relationships for HAP and birthweight, 31 we hypothesised that the levels observed during pilot work implied that exposure reductions would occur on the steep part of the response curve for birthweight. Given the relative paucity of studies on quantitative E-R analyses for HAP based on personal exposures, it is quite possible that the shape of the E-R curve is different than what was previously estimated.…”

Facing the Realities of Pragmatic Design Choices in Environmental Health Studies: Experiences from the Household Air Pollution Intervention Network Trial

“…HAPIN was designed to be a proof-of-concept, efficacy trial. Indeed, the investigators conducted at least 18 months of formative field research [ 20 , 21 , 22 , 23 , 24 ] or leveraged ongoing research [ 25 ] to identify study settings with low population density and low ambient air pollution. Formative activities included training personnel in ultrasound measurements to assess gestational period that met eligibility criteria [ 26 ], developing procedures for stove installation and training in stove use [ 10 ], assessing methods of fuel delivery to assure a continuous fuel supply, developing and implementing behavioral messages for intervention adherence, including monitoring temperature of biomass fuel stoves in intervention homes [ 13 ] and collecting outcome data within specific time windows [ 10 ].…”