A decadal analysis of particulate matter (PM2.5) and surface ozone (O3) over Vaal Priority Area, South Africa

Atmospheric pollutants that affect human health most significantly are particulate matter (PM2.5) and surface ozone (O3). This paper analysed the long-term temporal trends for PM2.5 and ground level O3 for six air quality monitoring stations in the Vaal Triangle Area of South Africa from 2007 to 2017. Research has been conducted on the short-term temporal trends for PM2.5 concentration and surface O3 concentrations. There are no studies that have focussed on the long-term temporal trends for PM2.5 and O3 in the Vaal Triangle Area of South Africa, because these air quality monitoring stations have only existed for a period of approximately 11 years. The data used in this study is derived from ground-based instruments from the South African Weather Service. Temporal patterns for time of day, days of the week, and seasons were observed for all air quality stations. PM2.5 concentration increased during early mornings and late afternoons, with higher concentration during weekdays than weekends and an increase from late winter through to spring and summer. Surface O3 concentrations peaked during the spring and summer months and during midday when there was maximum sunlight acting as a catalyst for photochemical reactions. The long term trends illustrated that there has been no significant decrease in annual average concentration for PM2.5 in four of the six stations and surface O3 for the six stations in the past 10 years in the Vaal Triangle Area of South Africa.