No abstract

The dithiothreitol (DTT) assay was used to investigate the oxidative potential (OP) of atmospheric fine particles (PM2.5) to form reactive oxygen species (ROS) during Diwali festival firework activity at a site in the Indo-Gangetic Plain, India. During the study period, the 12-hour mean PM2.5 was reported to be 263 ±151 µg m-3, which was 4.4 times higher than the NAAQS standards. Increased levels of gaseous pollutants (NOx, SO2, CO and O3), as well as metal concentrations such as Ba, Pb, Cu, Fe, Mg, K, Al, and Mn, were also observed during fireworks displays. The increased PM2.5-NOx slope for fireworks, which included traffic emissions, revealed that fireworks played a significant role. The highest value of OP of PM was detected in the next morning of Diwali, with a volume-based DTT value of 1.4 nmol min-1 m-3 and a mass-based DTT value of 11.8 pmol min-1 μg-1, implying higher PM-related DTT activity due to fireworks. A positive association was found between redox-active metals like Cr, Cu, Ni, and V and DTT activity which could be due to the ability of these metals to catalyse ROS generation in ambient air. Ba and Se concentrations in the particulate matter, which are key components of firecrackers, were likewise highly linked to DTT activity. During the daytime, ozone levels were strongly correlated (r2 = 0.9) with OPv activity; this may be due to photochemical processes which may lead to the formation of tropospheric O3. Elements C, O, Al, Si, S, K, and Ba were found to be the most prevalent in elemental mappings, which suggests that fireworks may have contributed to their abundance. A comparison of the daily OPv activity and hazard index (HI) suggests that the HI may be a poor metric for measuring the health impacts of PM exposure on human health.

This study focuses on the spatio-temporal variation in air quality caused by the nationwide Lamp event of nine minutes named as “#9pm 9min event” during the historic lockdown in the...

The potential of the atmospheric fine aerosols (PM2.5) to generate reactive oxygen species (ROS) during firework activity in Diwali festival was assessed by the dithiothreitol (DTT) assay at a site in the Indo-Gangetic Plain, India. The 12-h mean PM2.5 was found to be 262.9 ±150.7 µg m-3 during the study period which was 4.4 times exceeded the NAAQS limits. Firework activity was also characterized by increased levels of gaseous pollutants (NOx, SO2, CO and O3), and trace metal concentrations like Ba, Pb, Cu, Fe, Mg, K, Al and Mn. Elevated PM2.5-NOx slope for fireworks including traffic emissions suggested significant contribution of fireworks. The highest value of PM ROS activity, volume-based DTT value was 1.37 nmol min-1 m-3 and mass-based DTT value was 11.77 pmol min-1 μg-1, found in the next morning of Diwali, suggesting stronger PM associated ROS activity due to fireworks. A positive association was found between redox-active metals like Cd, Cr, Cu, Ni, and V and DTT activity that could be due to the ability of these metals to catalyze ROS generation in ambient air, while Ba, Be and Se in atmosphere as major constituents of firecrackers were also strongly associated with DTT activity. The ozone levels were strongly correlated (r2 = 0.87) with DTTv activity during daytime due to photochemical activities including chemical species associated with fireworks responsible for forming tropospheric O3. Comparison of the daily DTTv activity and hazard index (HI) suggests that the HI may be a poor metric to measure the health effects by which PM exposure can induce deterioration in human health.