Contrasting indoor and ambient particulate matter concentrations and thermal comfort in coal and non-coal burning households at South Africa Highveld

One of the key challenges noted in the sustainable development goals for good health and wellbeing (SDGs 3) is both ambient and household air pollution. Household solid fuel combustion represents one of the biggest threat to human health in South Africa. This study helps to understand the impact of solid fuel burning in an indoor and ambient environment. Continuous monitoring of particulate matter (PM4) was carried out in two houses, one used coal as a primary source of energy, while the other did not. For solid fuel burning (SFB) house the winter PM4 average 24-h concentration ranges between 60.9 μg m−3 and 207.5 μg m−3 while at non-solid fuel burning (NSFB) house it ranges between 15.3 μg m−3 and 84.2 μg m−3. In both houses, the national ambient air quality standard (NAAQS) for PM2.5 (40 μg m−3) were exceeded during winter. The summer PM4 levels ranged between 17.4 μg m−3 and 36.6 μg m−3 in the solid fuel burning house and between 14.2 μg m−3 and 39.9 μg m−3 at the non-solid fuel-burning house. During mornings and evenings, indoor concentrations were higher than the outdoor; these periods coincide with the fuel-burning pattern in this community. In the mid-afternoon, the outdoor PM levels sometimes went higher than the indoor levels, perhaps as a result of the pollution from the power plants in the neighbourhood. Using the linear regression model, there were no significant correlations between indoor/outdoor PM4 concentrations during the winter, but there were good correlations for both houses during the summer. There was an observed difference in the thermal comfort at the SFB and NSFB. The temperature at SFB went below the World Health Organisation standard in winter and above during the summer while at NSFB, the temperature was managed within the standard in both seasons.