Ambient and household exposure to particulate matter in a low income settlement

Abstract

Ambient and indoor exposure to particulate matter (PM) is a worldwide health problem, which is most prevalent in developing nations, and typically affects vulnerable groups (elderly, children, and sick people). In South Africa, where most low income communities rely on dirty solid fuels to satisfy their daily energy demands, the situation is no different. Although many houses are now electrified, the use of electricity as a primary energy carrier poses a huge economic burden to most impoverished households in the townships. Hence, people still rely on domestic combustion of dirty energy sources such as coal and wood to meet their household duties (cooking and heating) since are cheaper and easily accessible. Despite these benefits, little is known about the exposure that susceptible people, who live in such residential areas, experience because of the domestic burning of coal, in particular. This study was aimed at assessing the exposure of residential members that are subjected to ambient and indoor PM concentrations in Lebohang. Lebohang is a low income community located at the Mpumalanga Highveld, a region well known for having particulate concentrations, which frequently surpass the permissible NAAQS. To achieve the aim of this study, the outdoor PM2.5 and PM10 concentrations were firstly characterised using the ambient data collected from the monitoring station in Lebohang. Secondly, the indoor PM4 from 22 households that varied in structure and energy carrier use in the area; and which were sampled as part of the Sasol baseline monitoring campaign using DustTrak ll Model 8530 monitors, was also characterised. Thirdly, the indirect exposure assessment method was used well as the Monte Carlo simulation to estimate the PM exposure experienced by community members in Lebohang. These simulated estimates were based on outdoor and household PM measurements, the time activity data from the literature, and the 2011 Census community survey demographic information. It was found that ambient PM2.5 and PM10 in Lebohang were mostly at unhealthy levels, particularly during the cold period (May-August 2018) as both pollutants were not compliant with NAAQS. Meanwhile, the relatively clean ambient air quality was observed during the months that constitute the warm period (October 2017-February 2018). In terms of the indoor PM4, the 24h indoor concentrations of all houses enrolled in the study, regardless of their household type and primary energy carrier ranged between 24 and 482 μg.m-3. Surprisingly, based on the structural types, on average, formal homes (109 ± 67 μg.m-3) and informally structured households (105 ± 53 μg.m-3) measured similar indoor PM4 levels throughout the entire sampling period. Regarding PM exposure assessment, it was found that there are exposure inequalities in Lebohang and elderly people are the most susceptible group in this community. Finally, the study revealed that household exposure to PM contributes greatly to the total IPWE to PM concentrations residents experience in Lebohang.