Seasonal variation in metals concentration associated with settled dust and their risk assessment in school children of Agra (India)

Abstract

Metals associated with indoor dust are shown to be a key pollutant and resuspension of dust in critical microenvironments like schools can lead to detrimental health effects to children. The present study was carried out from December 2021 to November 2022 to examine variations in metal concentration with season and associated health risks from school dust in Agra, India. Dust samples were digested in aqua-regia followed by analysis for metals concentration by ICP-AES. Geo-accumulation (Igeo), pollution (PI), integrated pollution (IPI), and pollution load (PLI) indexes were used to determine metals contamination, Principal Component Analysis and Cluster Analysis were employed for the identification of causative sources of metals while USEPA health risk assessment models were utilized to assess the health risks in children. The results indicated that in all seasons settled dust of roadside schools of both regions accumulated higher concentrations of metals as compared to residential schools except semi-urban schools in post-monsoon season. The total metal concentration (mgkg−1) in school dust samples of Agra ranged from 62507–85037, 72477–97022, 48912–66083 to 58605–92290 in winter, summer, monsoon, and post-monsoon respectively. In all seasons, the PLI values of settled dust of all schools ranged from less than one to greater than unity which indicates pollution levels by metals. Further, Igeo values revealed that school dusts were moderately and heavily contaminated by Cd in all seasons. The assessment of health risk specifies ingestion as the main exposure route followed by dermal intake and inhalation. The Hazard Index value for all examined metals was lower than the safer limit of one while on the contrary for Pb, total cancer risk was higher the than safer limit via inhalation pathway. The findings of the study indicate that more investigations are required on potentially toxic metal contaminations in schools of Agra, especially for Pb, Cd and Cr.