Ambient air pollution has important impacts on a variety of environmental issues, particularly on human health and ecosystem
processes. A key tool for understanding the impacts of atmospheric pollution is through the long-term measurement of the ambient
concentrations of criteria atmospheric pollutants. Monitoring of ambient pollution concentrations has been conducted in two of the
National Air Quality Priority Areas since 2007. During this time period, significant changes in the management of air pollution have
occurred, including the adoption of the ambient air quality standards, and the implementation of Section 21 emission standards.
This paper examines the long-term evolution of ambient concentrations for PM and SO2 in the Vaal Triangle Airshed Priority Area and
Highveld Priority Area. These trends will be evaluated against the implementation of management interventions and the variation in
the measured concentrations and emerging areas of concern are highlighted.