Ambient and indoor particulate matter concentrations on the Mpumalanga highveld

Abstract

In order to better define tools for the protection of human health, the characterisation of particulate matter (PM) concentrations and the understanding of total exposure to these concentrations is critical. Many communities on the Mpumalanga Highveld in South Africa rely on coal for heating and cooking purposes. Consequently, individuals in such areas are often chronically and acutely exposed to elevated concentrations of PM, resulting in negative health impacts. An unprecedently rich data set was used to understand the magnitude as well as the spatial and temporal variability of PM concentrations in two low-income communities on the Mpumalanga Highveld, where solid fuel is the primary source of energy for heating and cooking purposes. Ambient, indoor and personal PM concentrations of different size fractions were simultaneously considered for analysis. Personal PM- and corresponding GPS measurements were used to define and contextualise personal exposure concentrations. Data was collected between 2013 and 2016 as part of Sasol and Eskom's air quality offset pilot study sampling campaigns in KwaDela and KwaZamokuhle, respectively. Results showed that air quality in KwaDela and KwaZamokuhle is very poor, especially so in winter months. Particulate matter concentrations were often found to be higher indoors than in the ambient environment. Ambient, indoor and personal measured PM concentrations were highly variable in space and time, as influenced by larger- and local scale meteorological conditions as well as by socio-economic factors. Peak personal exposure concentrations above the ambient air quality standards were not limited to a time of day nor to a specific micro-environment. However, high PM concentrations were most notable during peak burning times especially in and directly outside households. This study supports the notion that data logged at a centrally located ambient air quality monitoring station should be used with caution when making compliance related decisions and when conducting epidemiological studies in these areas. Whilst ambient air quality measurements are a useful guideline to use as a basis for air quality management interventions, it is important to include measurements taken in and around a household to ensure air quality management protocols are adequate to address the poor air quality that people breathe in low-income communities, and this particularly so on the Mpumalanga Highveld.