Abstract

MUYEMEKI, Luckson; BURGER, Roelof  and  PIKETH, Stuart J.. Evaluating the potential of remote sensing imagery in mapping ground-level fine particulate matter (PM₂₅) for the Vaal Triangle Priority Area. Clean Air J. [online]. 2020, vol.30, n.1, pp.1-7. ISSN 2410-972X.  http://dx.doi.org/10.17159/caj/2020/30/1.8066.

The quality of air breathed in South Africa is of great concern, especially in industrialised regions where PM₂₅ concentrations are high. Long term exposure to PM₂₅ is associated with serious adverse health impacts. Traditionally, PM₂₅ is monitored by a network of ground-based instruments. However, the coverage of monitoring networks in South Africa is not dense enough to fully capture the spatial variability of PM₂₅ concentrations. This study explored whether satellite remote sensing could offer a viable alternative to ground-based monitoring. Using an eight-year record (2009 to 2016) of satellite retrievals (MODIS, MISR and SeaWIFS) for PM₂₅ concentrations, spatial variations and temporal trends for PM_2.5 were evaluated for the Vaal Triangle Airshed Priority Area (VTAPA). Results were compared to corresponding measurements from the VTAPA surface monitoring stations. High PM₂₅ concentrations were clustered around the centre and towards the south-west of the VTAPA over the highly industrialised cities of Vanderbijlpark and Sasol-burg. Satellite retrievals tended to overestimate PM₂₅ concentrations. Overall, there was a poor agreement between satellite-retrieved PM₂₅ estimates and ground-level PM₂₅ measurements. Root mean square error values ranged from 6 to 11 μg/m³ and from -0.89 to 0.32 for the correlation coefficient. For satellite remote sensing to be effectively exploited for air quality assessments in the VTAPA and elsewhere, further research to improve the precision and accuracy of satellite-retrieved PM₂₅ is required.

Keywords : Satellite retrievals; ground-based data; PM₂₅ concentration; spatial variations.

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