Firecrackers during Diwali/Deepavali are reported to be the main source of Delhi’s post-festival PM2.5 pollution, with multiple outlets citing an IITM Pune assessment based on an emissions modelling system. Coverage says the share linked to crackers is highest around the days immediately after the festival, then falls as the period progresses.
The reported numbers largely align across outlets, with vehicular emissions described as a relatively small contributor during the peak assessment window. The studies also attribute smaller fractions of PM2.5 to secondary inorganic and secondary organic aerosols, along with some contribution from waste burning.
Differences in coverage are mainly in the exact timing and the headline figure used (ranging around the high-70s to about 71%), as well as how explicitly outlets mention the day-to-day change in contribution across a multi-day window. Some headlines emphasise “Delhi’s pollution” generally, while others specify “post-Deepavali” or “after Diwali” periods and focus on the relative ranking of pollution sources.
