Geospatial determinants of maternal and child exposure to fine particulate matter in Kintampo, Ghana: Levels within the household and community, by building density and nearby roadways

Abstract

Background/Aim. Personal exposure to fine particulate matter (PM₂.₅) from household air pollution is well-documented in Sub-Saharan Africa, but spatial patterns of exposure are poorly characterized. Our study aimed to evaluate personal exposure to PM₂.₅ when within the household and community, and during typical hours of cooking, among mothers and children in rural communities near Kintampo, Ghana. We also explored other geographic determinants of exposure. Methods. Our study included 259 sessions of geolocated, gravimetrically-calibrated one-minute PM₂.₅ measurements from participants in the GRAPHS Child Lung Function Study. Household boundaries were defined using a 50-meter buffer around participants’ homes. Community boundaries were developed by applying a spatial clustering algorithm to an open-source dataset of building footprints in Africa. For each GPS location, we estimated building density (500m buffer) and proximity to roadways (100m buffer). We estimated the percentage change in logarithm PM₂.₅ by location (household, community), time of day (morning/evening cooking hours versus nighttime), building density and proximity to roadways using linear mixed effect models. Results. Relative to nighttime household exposures, PM₂.₅ exposure during evening cooking hours increased by 175% (95CI=162-188%) and 75% (95CI=50-105%) in the household and community, respectively. Exposures were elevated in areas with the highest versus lowest quartile of building density (Q1vsQ4=28%, 95CI=14-45%). The effect of building density was strongest when modeled jointly with evening cooking hours, and influenced levels in both the household and community (64% and 82% increase from Q1 to Q4, respectively). Being proximal to a tertiary or trunk roadway increased PM₂.₅ exposure by 44% (95CI=24-67%) and 13% (95CI=4-22%), respectively. Conclusions. Our findings suggest that neighbors’ cooking and other community PM₂.₅ sources contribute substantially to personal PM₂.₅ exposure. Building density may exacerbate community exposures when multiple households are cooking simultaneously. Proximity to tertiary or trunk roadways increase personal PM₂.₅ exposure. Keywords. Air pollution; exposure assessment; spatial statistics