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Exposure to particulate matter less than 2.5 µm in diameter (PM2.5) is a cause of concern in cities and major emission regions of northern India. An intensive field campaign involving the states of Punjab, Haryana and Delhi national capital region (NCR) was conducted in 2022 using 29 Compact and Useful PM2.5 Instrument with Gas sensors (CUPI-Gs). Continuous observations show that the PM2.5 in the region increased gradually from < 60 µg m−3 in 6–10 October to up to 500 µg m−3 on 5–9 November, which subsequently decreased to about 100 µg m−3 in 20–30 November. Two distinct plumes of PM2.5 over 500 µg m−3 are tracked from crop residue burning in Punjab to Delhi NCR on 2–3 November and 10–11 November with delays of 1 and 3 days, respectively. Experimental campaign demonstrates the advantages of source region observations to link agricultural waste burning and air pollution at local to regional scales. [ABSTRACT FROM AUTHOR]

The study assesses 13 air pollutants, including VOCs from fireworks during the Diwali festival from 2017 to 2020, in six Indo Gangetic Plains (IGP) states. Percentage increase in 8-h average nighttime concentrations on Diwali compared to the previous night and Pearson correlation analysis were used to assess the pollutants emitted from fireworks. Stubble burning (SB) season in IGP coincides with Diwali festival every year and its influence on ambient air during Diwali was also checked. Air quality on Diwali had an additional effect of SB emissions during all years and maximum was observed in 2018. Results showed that PM 2.5 and SO 2 are emitted as major fractions from fireworks. NH 3 , NO and ethyl-benzene were also prominent in firework emissions but in lesser proportions. The highest hourly PM 2.5 concentration was found above 900 μg/m3 in 2017 in Delhi. Ozone rarely showed an increase and was negatively correlated with all pollutants during all years. Only PM 2.5, among the major emissions from fireworks, showed significant Long-Range Transport (LRT) in IGP. NO, CO and PM 2.5 in years which had more stubble burning, showed their regional transport to lower IGP due to their longer atmospheric lifetimes and meteorology. These same years had an excessive increase in NO and CO concentrations on Diwali. The combined effect of SB with firework emissions resulted in more elevated trends for the coming days. The years with maximum fireworks were 2019 in Punjab and Haryana, 2017 in Delhi and 2018 in Uttar Pradesh, Bihar and West Bengal. In 2020, least fireworks were observed among all states, showing the positive effects of a ban on burning fireworks in the whole airshed of IGP. The study fills the gap in evaluating the combined impact of Diwali fireworks and SB emissions on the air quality of IGP airshed, which was missing in the literature. [Display omitted] • There was no significant nighttime ozone formation observed from fireworks. • PM 2.5 , SO 2 are emitted as major fractions from fireworks. • Firework emissions during excessive stubble burning uplift the levels of all pollutants, including VOCs, for coming days. • The years with prevailing stubble burning emissions have very high concentrations of CO & NOx all over IGP. [ABSTRACT FROM AUTHOR]