Analysis for suspension time of airborne particles due to Diwali fireworks in an urban atmosphere Lucknow

The study analyzed the additional load and suspension time of particle pollutants emerging from Diwali firecracker combustion between two different urban landscape sites in Lucknow, India. PM_# (1, 2.5, and 10) and PSD (range: 0.2 μm to 20 μm), and chemical speciation of 15-elements and 6-ions of PM_2.5 were assessed for Diwali and non-Diwali-days. In the commercial site, pre-Diwali-days to Diwali-day and pre-Diwali-days to post-Diwali-days added an extra load of PM_# in the atmosphere by 3 to 5 times and 1.5 to 2 times respectively. Whereas, in the residential site, 2 to 3 times and 1 to 1.5 times increased PM_# was observed. Variations in PM_# suspension time due to Diwali fireworks were found as ~10 days at residential site and ~6 days at commercial site due to dissimilarities in the local source mix. Further, unimodal and bimodal PSD distributions and nearness observed between PSDs in two of the study sites revealed the influence of relative sources during Diwali and non-Diwali-days. Chemical markers of Diwali fireworks were identified as abundant in PM_2.5 during Diwali and post-Diwali-days, but less in pre-Diwali-days. A strong correlation between markers of Diwali fireworks and their occurrence with PCA groups further confirmed the suspension period of PM_# even during post-Diwali-days.