Pollution from carbon monoxide, nitrogen dioxide, sulphate and suspended particulate matter due to ignition of fireworks during the festival of Diwali is well established. Although surface ozone exhibits high natural variability throughout the year, any short term enhancement in ozone levels coupled with high level of pollutants during Diwali might prove to be deadly for a large number of elderly people and children with heart and respiratory ailments. Despite this fact, very little study on surface ozone pollution during the festival of Diwali has been reported from India so far. In the light of these observations, the changes in ozone concentration observed during Diwali at New Delhi in India have been studied to determine the amount and possible causes of ozone pollution apart from pollution due to ignition of fireworks.