Exposure risk and source analysis of toxic metal(loid)s in indoor dust of Eastern Nigeria during COVID-19 lockdown

Abstract

Outbreak and emergency occasioned by coronavirus virus disease forcefully led to imposition of lockdown in Nigeria; a situation that consequently exposed humans to heavy metal(loid)s laden dust. Hence, this study measured the concentration of heavy metal(loid)s in indoor dust from households of three selected semi-urban areas (Rumuodomaya-Ogale, Ekwulobia and Awka) of Eastern Nigeria. Dust samples (n = 144) were collected from household’s windows and floors using clean brush, filtered, digested by standard method and analyzed for Cd, Co, Ni, Hg, As, Mn, Al, Pb, Cr, Zn, and Fe using Atomic Absorption Spectrometry (Model: Varian AA240, USA). Results show that Fe was dominant when compared to other metals assessed. Whereas the total heavy metal(loid)s concentration (THMC) of the floor dusts was higher than that of window dusts from Ekwulobia, there was no significant difference (p > 0.05) in total heavy metal(loid)s level in window and floor dust of the three semi-urban areas across the months. Awka showed the least THMC in the window (1.17 – 1.52 mg kg −1 ) and floor (1.08 – 2.35 mg kg −1 ) dusts in comparison with Ekwulobia (window: 1.23 mg/kg to 9.05 mg kg −1 ; floor: 1.27 mg kg −1 to 9.22 mg kg −1 ) and Rumuodomaya-Ogale (window: 1.49 – 2.70 mg kg −1 ; floor: 1.24 – 2.23 mg kg −1 ). The cancer and non-cancer risk of exposure to the heavy metal(loid)s dusts was insignificant while most of the heavy metal(loid)s could be related to anthropogenic origin based on the Positive Matrix Factorization and Principal Component Analysis models. • Heavy metal(loid)s (HMs) in dusts of Ekwulobia was high during COVID-19 lockdown. • Indoor cooking contributed to the HMs concentrations of the three residential areas. • Cancer and non-cancer risk of exposure to HMs in the indoor dusts were negligible. • The dust quality assessments showed low contamination and ecological risk.