Abstract:The effect of fireworks on the air quality was assessed from the ambient concentrations of various air pollutants (SO 2 , NO 2 , PM 10 and TSP) during Diwali festival in Hisar city (India), in November 1999. The extensive use of fireworks was found to be related with short-term variation in air quality. During the festival the concentration of SO 2 was observed to be increased ~10 -fold at few sites, whereas the concentrations of NO 2 , PM 10 and TSP increased 2-3 times, compared to the data collected on a typical winter day in December 1999. The maximum NO 2 concentration was observed a day after the festival. The diurnal pattern of the above pollutants showed a slight increase in the night. The levels of these pollutants observed during Diwali were found to be moderately high, which can be associated with serious health impacts.