A study was conducted in the residential areas of Delhi, India, to assess the variation in ambient air quality and ambient noise levels during pre-Diwali month (DM), Diwali day (DD) and post-Diwali month during the period 2006 to 2008. The use of fireworks during DD showed 1.3 to 4.0 times increase in concentration of respirable particulate matter (PM(10)) and 1.6 to 2.5 times increase in concentration of total suspended particulate matter (TSP) than the concentration during DM. There was a significant increase in sulfur dioxide (SO(2)) concentration but the concentration of nitrogen dioxide (NO(2)) did not show any considerable variation. Ambient noise level were 1.2 to 1.3 times higher than normal day. The study also showed a strong correlation between PM(10) and TSP (R (2) ≥ 0.9) and SO(2) and NO(2) (R (2) ≥ 0.9) on DD. The correlation between noise level and gaseous pollutant were moderate (R (2) ≥ 0.5). The average concentration of the pollutants during DD was found higher in 2007 which could be due to adverse meteorological conditions. The statistical interpretation of data indicated that the celebration of Diwali festival affects the ambient air and noise quality. The study would provide public awareness about the health risks associated with the celebrations of Diwali festival so as to take proper precautions.

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A short-term study was conducted with a view to assess the ambient air quality in the surroundings area of compost plant at Okhla, Delhi. Three selected locations viz., CRRI Campus, Hazi Colony, and Gaffar Manzil were selected during the month of November 2008. The study revealed that 24 hourly average concentration of respirable suspended particulate matter (RSPM) at all selected locations were alarmingly high as compared to National Ambient Air Quality Standards (NAAQS) specified by Central Pollution Control Board (CPCB) 2009, during the study period. The 24 hourly average concentrations of sulphur dioxide (SO 2 ) and ammonia (NH 3 ) were within the permissible limits prescribed by the NAAQS. Nitrogen dioxide (NO 2 ) concentration was found to exceed the permissible limits at all the three locations with percent exceedence ranging between 67%-75%. High concentrations of NO 2 could be due to auto-exhaust emissions on Delhi-Mathura road, burning of LPG gas for domestic use, incinerator stack gases and diesel run electric generator. The concentrations of H 2 S were low, which could be due to aerobic nature of waste processing composting plant. The 8 hourly average concentration of CO was quite high at all the three monitoring stations. Percent exceedence of CO levels ranged between 83% -86%. The localized domestic and automobile emissions in surrounding areas could be the major contributor of CO. The overall assessment of the air quality during the study period at selected locations indicated that the maximum contribution of pollutant responsible for critical Air Quality Index (AQI) values was the respirable particulate matter (RSPM) which fell under the category of severe on majority of the days.