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Abstract
Objectives: 1) To evaluate the effectiveness of a liquefied petroleum gas (LPG) intervention in reducing HAP exposures among middle- and older-aged women, 2) characterize the major factors associated with black carbon (BC) exposures among pregnant women, 3) assess the role these factors play in modifying the BC exposure reduction via an LPG stove intervention, and 4) compare BC measures from the same optical instrument using two slight variations of the same optical absorption technique. Methods: Up to six repeated exposure measures were conducted for approximately 3,200 households enrolled in the Household Air Pollution Intervention Network (HAPIN) trial. The HAPIN study population included 3,195 pregnant women, their children, and 418 nonpregnant adult women. Personal particulate matter (PM2.5), carbon monoxide (CO), and BC were collected. Light absorbing carbon (LAC) was measured as a surrogate for BC. At each measurement visit, questionnaires were administered to collect individual- and household-level information. After baseline exposure visit, households were randomly allotted to either control (continued use of traditional biomass stove) or intervention (use of LPG stove) arm.
Results: The relationship between BC measures using pre-sampled filter scans versus laboratory blank filters as a reference was strong (R2: 0.97); however, this relationship (R2 = 0.25 – 0.26) was weak in low exposure settings (1.3 – 2.9 μg/m3). We identified stove type, kerosene use, study site, whether cooking activity, primary lighting source, other sources of smoke, kitchen location, roof material, participant occupation, hours of stove use, season, temperature, and relative humidity to be significant predictors of personal BC exposures among pregnant women. The contrast in prenatal BC exposures between study arms, post-randomization, differed according to study site, adherence to the assigned study stove, and cooking activity. We observed significant reductions in household air pollution exposure among middle- and older-aged women from the HAPIN LPG intervention.
Conclusion: Our results suggests that an LPG stove intervention can substantially and consistently reduce HAP exposures, including BC, for individuals relying on solid fuels for cooking. Our data also highlights several important factors that can potentially attenuate the effectiveness of an LPG intervention in reducing BC as well as measurement procedures that can provide more accurate estimates of BC exposure.