Inhalation health risk assessment of ambient PM_2.5 and associated trace elements in Cape Town, South Africa

Abstract

Few human health risk assessment studies of air pollution exist in Africa. This study used the US EPA health risk framework to investigate the human health risks due to inhalation exposure to ambient PM_2.5 and some of its trace element composition (Cl, Si, and Ti) in Cape Town, South Africa, for 12 months (April 2017 to April 2018). The safe average daily dose was determined using the yearly WHO guideline and South African ambient air quality standard for PM_2.5 and the US EPA regional screening levels for trace elements. The average yearly PM_2.5 concentration (13 µg/m³) was above the yearly WHO guideline (5 µg/m³), but below the yearly South African standard (20 µg/m³). The average yearly PM_2.5 concentration posed a low risk to adults (Hazard Quotient = 0.66) compared to infants (HQ = 2.13) and children (HQ =1.96). Cl posed health risks to all age groups (HQ > 1). The study concludes that PM_2.5 and its trace element components pose adverse health effects to all population age groups. The toxicity of PM_2.5 depends on its composition; hence this study recommends a source apportionment study to quantify the source contributions and inform the right abatement strategies.

Keywords:

• Cape Town
• human health risk assessment
• inhalation exposure
• PM_2.5
• trace elements

Acknowledgments

The authors would like to thank John Peter Williams, who conducted the sampling of the PM_2.5 data used in this study as part of his MSc studies at the University of the Western Cape.

Authors’ contribution

This manuscript was part of the Ph.D. project of Anna Alfeus. Prof Janine Wichmann and Dr. Joyce Shirinde supervised the Ph.D. thesis. Anna Alfeus (AA*), Joyce Shirinde (JS), Peter Molnar (PM), Johan Boman (JB), and Janine Wichmann (JW) are the authors of this manuscript. AA* wrote the draft manuscript. PM and JB did data curation. The current version of the manuscript was approved by all authors.

Data availability

The authors are working on other manuscripts with the data, hence the data is not available to the public.

Disclosure statement

The authors declare no conflict of interest.

Additional information

Funding

The authors acknowledge the University of Pretoria doctoral bursary, University of Namibia Staff Development office and the AGNES grant office for funding this study. JW received data collection and analysis funding with an NRF grant (UP Faculty of Health Sciences Ethics ref. 36/2017).