Health risks from airborne heavy metals in particulate matter: Evidence from a Southeast Asian megacity, Dhaka, Bangladesh

Air pollution from heavy metals (HMs) presents a growing threat to public health in rapidly urbanizing cities like Dhaka, Bangladesh. This study aimed to quantify the concentrations of HMs in total suspended particulate (TSP) and assess the associated health risks in Dhaka city. TSP samples were collected from residential, educational, construction and waste-related areas and analyzed using inductively coupled plasma mass spectrometry (ICP-MS) for 13 metals: As, Se, Pb, Cd, Co, Cr, Cu, Mn, Ni, Zn, V, Fe and Al. The highest TSP concentration was recorded at medical waste site (459.3 ± 180.0 µgm −3 ), exceeding the US EPA standard (150 µgm −3 ) by more than threefold. Zn showed the highest concentration (8.306 ± 2.621 µgm −3 ) at the municipal waste site, while Pb and Cd levels significantly surpassed WHO guidelines, with Pb reaching nearly six times and Cd 16 times the recommended limits. Health risk assessment revealed non-carcinogenic hazard index (HI) values between 27.39 and 61.36, far exceeding the safety threshold (HI = 1), with Cu contributing the highest hazard quotient (HQ = 31.17) in residential areas. Carcinogenic risk (CR) values for Cr, As, Cd, Pb, Co, and Ni also exceeded acceptable levels (1 ×10 −6 ), where Cr poses the highest risk (7.43 ×10 −2 ) at the municipal waste site. These findings emphasize the urgency for stricter air quality regulations, improved waste management and pollution source control to mitigate the health impacts of airborne HMs in Dhaka. Our future studies would explore long-term exposure effects and trace pollution sources to inform targeted interventions.