Health risk assessment of PM_2.5 and PM_2.5-bound trace elements in Pretoria, South Africa

Abstract

Exposure to outdoor air pollutants poses a risk for both non-carcinogenic and carcinogenic respiratory disease outcomes. A standardized health risk assessment (US EPA) utilizes air quality data, body mass and breathing rates to determine potential risk. This health risk assessment study assesses the hazard quotient (HQ) for total PM_2.5 and trace elemental constituents (Br, Cl, K, Ni, S, Si, Ti and U) exposure in Pretoria, South Africa. The World Health Organization (WHO) air quality guideline (5 µg m⁻³) and the yearly South African National Ambient Air Quality Standard (NAAQS) (20 µg m⁻³) were the references dosages for total PM_2.5. A total of 350 days was sampled in Pretoria, South Africa. The mean total PM_2.5 concentration during the 34-month study period was 23.2 µg m⁻³ (0.7–139 µg m⁻³). The HQ for total PM_2.5 was 1.17, 3.47 and 3.78 for adults, children and infants. Non-carcinogenic risks for trace elements K, Cl, S and Si were above 1 for adults. Seasonally, Si was the highest during autumn for adults (1.9) and during spring for S (5.5). The HQ values for K and Cl were highest during winter. The exposure to Ni posed a risk for cancer throughout the year and for As during winters.

Keywords:

• Air pollution
• particulates
• seasonal
• respiratory diseases
• risk
• sources
• cancer

Acknowledgments

The authors wish to thank Adewale Ayedemi and Nandi Mwase for PM_2.5 sampling campaigns than ran during the 2017–2018 and 2018–2019 years, respectively, at the School of Health Systems and Public Health, University of Pretoria.

Ethical approval

The study obtained approval from the Faculty of Health Sciences Research Ethics Committee, University of Pretoria (References 36/2017 and 300/2020) on 21 February 2021.

Author contributions

Conceptualization, J.W.; sampling for 2019–2020, C.H.-D.; formal analysis, C.H.-D.; investigation, J.B and P.M.; resources, J.B.; data curation, C.H.-D.; writing—original draft preparation, C.H.-D.; review and editing, C.H.-D.; supervision, J.W., J.B. and P.M. All authors have read and agreed to the published version of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Data are available upon request, but if used in another manuscript the authors wish to be included as coauthors.

Additional information

Funding

J.W. received funding from the South African National Research Foundation (Collaborative Postgraduate Training Program grant CPT160424162937). The sources of funding had no influence on the project.