Diwali is one of the largest festivals for Hindu religion which falls in the period October-November every year. During the festival days, extensive burning of firecrackers takes place, especially in the evening hours, constituting a significant source of aerosols, black carbon (BC), organics, and trace gases. The widespread use of sparklers was found to be associated with short-term air quality degradation events. The present study focuses on the influence of Diwali fireworks emissions on surface ozone (O3), nitrogen oxides (NO x ), and BC aerosol concentration over the tropical urban region of Hyderabad, India during three consecutive years (2009-2011). The trace gases are analyzed for pre-Diwali, Diwali, and post-Diwali days in order to reveal the festivity's contribution to the ambient air quality over the city. A twofold to threefold increase is observed in O3, NO x , and BC concentrations during the festival period compared to control days for 2009-2011, which is mainly attributed to firecrackers burning. The high correlation coefficient (~0.74) between NO x and SO2 concentrations and higher SO2/NO x (S/N) index suggested air quality degradation due to firecrackers burning. Furthermore, the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation-derived aerosol subtyping map also confirmed the presence of smoke aerosols emitted from firecrackers burning over the region. Nevertheless, the concentration level of pollutants exhibited substantial decline over the region during the years 2010 and 2011 compared to 2009 ascribed to various awareness campaigns and increased cost of firecrackers.

In this study, temporal variations of surface ozone (O3) were investigated at tropical urban site of Hyderabad during the year 2009. O3, oxides of nitrogen (NOx = NO + NO2), black carbon (BC), and meteorological parameters were continuously monitored at the established air monitoring station. Results revealed the production of surface O3 from NO2 through photochemical oxidation. Averaged datasets illustrated the variations in ground‐level concentrations of these air pollutants along different time scales. Maximum mean concentrations of O3 (56.75 ppbv) and NOx (8.9 ppbv) were observed in summer. Diurnal‐seasonal changes in surface O3 and NOx concentrations were explicated with complex atmospheric chemistry, boundary layer dynamics, and local meteorology. In addition, nocturnal chemistry of NOx played a decisive role in the formation of O3 during day time. Mean BC mass concentration in winter (10.92 µg m−3) was high during morning hours. Heterogeneous chemistry of BC on O3 destruction and NOx formation was elucidated. Apart from these local observations, long‐range transport of trace gases and BC aerosols were evidenced from air mass back trajectories. Further, statistical modeling was performed to predict O3 using multi‐linear regression method, which resulted in 91% of the overall variance.

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