Assessment of trace metal concentration in the ambient air of the Prayagraj City during Diwali festival-a case study.

Abstract

The study evaluated the particulate matter trend and trace element concentrations, during the Diwali week for two consecutive years, November 2018 and October 2019. Diwali celebrations worsen the city's air quality from poor to a severe category of air quality index (AQI). A peak rise in PM10 concentration was found on Diwali day, 1.8 times more than a normal day of the same period. The concentration was 5.6-fold more than the permissible limit prescribed by National Ambient Air Quality Standards (NAAQS), India, and 11.26-fold higher than the permissible limit of World Health Organization (WHO). The more firework bursting in the year 2019 results in the rise of PM10 concentration by 132% compared with the previous year. Lead (Pb), a carcinogen, was found in higher levels, in Diwali samples of year 2019. The average metal concentration on Diwali day was found in the following order: Pb (396.17) > Cu (70.34) > Mn (66.34) > Cr (29.66) > Ni (4.96) in year 2019 while Ni (195.20) > Pb (149.45) > Mn (64.85) > Cu (13.44) in year 2018. A significant positive correlation between Cr and Pb, Cu and Pb, Cr and Cu, and with PM10 have been observed, indicating their emission from a common source and the contribution of firecrackers to particulate pollution. Principal component analysis (PCA) identified the contribution of the bursting of firecrackers and vehicular emissions towards PM10 pollution in the year 2019 and vehicular emissions and dust resuspension in the year 2018 over the megacity Prayagraj.