Household PM2.5 in a South African urban and rural setting: A comparative analysis using low-cost sensors

Household air pollution (HAP) is responsible for millions of premature deaths each year . Exposure to household air pollutants as a risk factor for poor health has not been adequately quantified in many parts of the world, especially Sub-Saharan Africa. We aimed to assess HAP, specifically PM 2.5 , and its associations with dwelling and household characteristics in urban (Soweto) and rural (Agincourt) settings in South Africa. We monitored indoor PM 2.5 concentrations in 40 unique households using low-cost sensors, across two study sites and seasons. Low-cost sensors were calibrated by collocation, and associations between dwelling and household characteristics with indoor PM 2.5 concentrations were assessed using a log-linear regression model. PM 2.5 concentrations were greater in urban households in the summer (50 μg/m 3 (95% CI: 41–63) and in the winter (82 μg/m 3 (95% CI: 62–109)) compared to rural households (summer: 19 μg/m 3 (95%: CI 14–26) and winter: 48 μg/m 3 (95% CI: 44–53)). The log-linear model (n=39) explained 74% of the variance in leave-one-out cross validation. Significant associations with household PM 2.5 were observed with the following: the season, study setting, presence of tobacco smoking, presence of incense burning inside the dwelling, and the use of heating. This study found significant variations in HAP concentrations within and across the urban and rural communities, likely influenced by differences in ambient outdoor concentrations and individual behaviours such as incense burning. It is crucial to enhance community and policy maker awareness regarding the dangers of indoor smoking and the harmful effects of burning incense indoors. • Mean household concentrations of PM 2.5 were more than double in the urban study setting (64 μg/m 3 ) compared to the rural study setting (29 μg/m 3 ) • Mean household concentrations of PM 2.5 doubled in the winter month (64 μg/m 3 ), compared to the summer month (32 μg/m 3 ) • International and national guidelines were exceeded in the majority of households (86% and 52%, respectively) • Household PM 2.5 was associated with the presence of burning incense and environmental tobacco smoke (both associated with a 44% increase) • Incense burning occurred only in the urban study sample