Multivariate toxicological assessments of inhaled fine-submicron particle-bound metals in school-aged children of Dhaka city

Abstract

Dhaka, being one of the most air-polluted cities, experiences a peak pollution level during the dry winter due to its geographical location, climatic conditions, regional urban activities, and air mass trajectories, which are exacerbated by transboundary effects; a reduced pattern was observed during monsoon. Fine and submicron particle (PM_2.5 and PM₁)-bound metals were investigated in fifteen schools across three least-to-polluted cluster regions in Dhaka during the monsoon and winter to identify the dreadful impact of air pollution on school-age children whose airways are smaller and still developing. Children's respiratory deposition flux (RDF) showed PM₁ had a higher retention of metals in alveolar regions, which accounts for 86.91–93.23 % of PM_2.5. In addition, inhalation significantly contributes to both carcinogenic and non-carcinogenic risks, 89.51 % and 72.62 % of the total, respectively. Regarding non-carcinogenic risk, Mn and Pb showed the maximum hazard quotient (HQ) values (3.3 and 2.6) in school environments of industrial and commercial areas, respectively. The Cr, As, and V were the predominant contributors to substantial carcinogenic risk for children. The positive matrix factorization (PMF) deciphers the release of Cr, Mn, and Ni into the atmosphere from industries, whereas automobile exhaust, coal combustion, and heavy-oil combustion solely emit Pb, As, and V in the air, respectively. In industrial and commercial areas, the cancer risk of children was 65 and 36.6 times higher than in residential zones, respectively. This study intends to identify and categorize distinct pollution sources and their potential risks, consequently providing the required information to develop an integrated approach to reduce emissions.