Human health risks of inhalable exposure to PM2.5 in Pretoria, South Africa

Abstract

Aim: The aim of this project was to measure PM2.5, soot, black carbon, and UV particulate matter, and assess the health risks PM2.5 poses to humans in Pretoria, as part of my MSc (Epidemiology) project. Design: The study is a two-part study combining an exposure assessment and Human Health Risk Assessment study. Setting: The study was conducted in an urban background area located in Pretoria, Gezina, South Africa. The area is mostly a residential area, away from the highway and without much heavy traffic. Data and method: Gravimetric analysis was used to determine PM2.5 concentrations every third day from 19 April 2019 to 23 April 2019. An estimate of possible health risks from exposure to airborne PM2.5 was performed using the USA Environmental Protection Agency human health risk assessment framework. A scenario-assessment approach was utilised, where normal (average exposure) and worst-case (continuous exposure) scenarios were developed for intermediate (24-hour) and chronic (annual) exposure periods for different exposure groups (infants, children, adults). Outcome measures: Absence of major adverse health effects from exposure to airborne pollutants. Results: The average annual ambient concentration of PM2.5 was 21.5 ± 13.6µg/m3, which was higher than the annual PM2.5 World Health Organization air quality guideline. Infants and children, rather than adults, are more likely to be affected by 24-hour exposure. Additionally, for chronic annual exposure, PM2.5 posed low health risks to sensitive individuals, with the severity of risk varying across exposed groups. Conclusion: Levels of PM2.5 posed a low health risk to people in Pretoria, however a follow-up study should investigate the risks posed by the PM2.5 chemical composition. It is recommended that the City of Tshwane Air Quality Management Plan, which is currently under review, addresses local and long-range sources of PM2.5 in the city.