Human health risk evaluation of particle air pollution (PM10 and PM2.5) and heavy metals in Dakar's two urban areas

Abstract

Air pollution is a major problem, including harmful elements such as particulate matter (PM) and heavy metals (HMs). These pollutants are among the leading causes of premature death. This study assesses the health effects of PM₁₀, PM_2.5, and HMs between 2018 and 2019 in two areas of Dakar, Senegal: Hlm (industrial site) and Yoff (coastal and urban site). Numerous PM samples were collected, and 69 samples from each size fraction were selected for this study. Energy-dispersive X-ray fluorescence (ED-XRF) spectroscopy was used to analyse the PM and identify the HMs present in the samples. The relative risk (RR) and attributable fraction (AF) of exposure to PM₁₀ and PM_2.5 were estimated to assess mortality and morbidity. The average PM₁₀ concentrations were 232.318 μg/m³ at Hlm and 209.854 μg/m³ at Yoff, while the highest PM_2.5 concentrations reached 309.355 μg/m³ at Hlm and 319.172 μg/m³ at Yoff. For short-term exposure to PM₁₀, the RR for all-cause mortality across all age groups was 1.195% at Hlm and 1.174% at Yoff. The RR for respiratory mortality in children under five was 1.428% at Hlm and 1.377% at Yoff. For long-term exposure to PM_2.5, the RR for cardiopulmonary mortality showed slight variations between the two sites (1.964% at Hlm and 1.973% at Yoff). Similarly, the RR for lung cancer in individuals aged over 30 years was 2.746% at Hlm and 2.766% at Yoff. Additionally, the assessment of HM exposure through three routes (inhalation, ingestion, and dermal contact) allowed for the determination of the hazard index (HI) and carcinogenic risk (CR). At both sites, none of the HI values for Cr, Cu, Mn, Ni, V, and Zn exceeded the threshold of 1. This study also revealed that the CR values for Cr, Ni, and Pb were outside the regulatory range of 10^–6 and 10^–4.

Graphical Abstract