Concentrations and health risks of particulate matter (PM2.5) and associated elements in the ambient air of Lagos, Southwestern Nigeria

Abstract

Particulate matter (PM) exposure from ambient air has been implicated in several diseases, which necessitates periodic air monitoring in every dwelling place, particularly urban centers, to detect overexposure early. The main objective of this study was to determine the levels of PM2.5 and associated elements, namely carbon monoxide (CO), ozone (O3), and nitrogen dioxide (NO2) in Lagos, Nigeria. An
Aerosol Mass Monitor was employed to quantify the concentrations of PM2.5, NO2, CO, and O3 at ten selected locations in the city, namely, Allen Avenue, Kolington, Isheri, Badagry, Opebi, Eti-Osa, Ajeniya, Awolowo, Orile, and Ajegunle. The values obtained were thereafter used to estimate the hazard quotient (HQ) of the average hourly dose (AHD) and average daily dose (ADD) exposures to the particles. The results revealed that PM2.5 levels in all the locations were above the 15µg/m3 permissible level recommended by the World Health Organization (WHO), except in Badagry (5.36µg/m3). NO2 was above the 25µg/m3 permissible level in all locations except in Badagry (6.11µg/m3) and Ajeniya (0.00µg/m3). Meanwhile, in all the locations, CO was above the tolerable level (i.e., >7µg/m3) while O3 was within permissible levels (i.e., <100µg/m3). The HQ of the AHD of the pollutants was less than the threshold of 1, but the HQ of the ADD was greater than 1 in many locations. It can be inferred from the results that daily exposure to PM2.5, NO2, and CO in the city can cause serious health consequences for residents. Agencies in charge of health and the environment in the city are advised to formulate policies towards pollution reduction.