Firecrackers drive Delhi air pollution after Deepavali, IITM data shows

Firecrackers emerged as the biggest driver of Delhi's air pollution on November 9 and November 10, according to source-apportionment estimates from the Indian Institute of Tropical Meteorology. Firecrackers accounted for 71.1% of the pollution load on Monday, November 9, which was a day after Deepavali. This contribution dropped to 29.8% on Tuesday, November 10. The estimates carried a standard deviation of 104.1 percentage points on Monday and 27.7 percentage points on Tuesday, showing considerable variability and uncertainty in the models. On Monday, vehicular emissions made up 6.9% of the pollution. Secondary inorganic aerosols followed at 5%, while secondary organic aerosols contributed 4.5%. Mixed or unresolved biofuel stood at 4.45%, and mineral dust and ash along with mixed combustion each accounted at 2.5%. Wood burning contributed 1.3%, and waste burning involving municipal and plastic-rubber waste made up 1.1%. Coal combustion and industrial emissions contributed 0.5% and 0.2% respectively. On Tuesday, secondary organic aerosols became the second-largest contributor at 17.5%. Vehicular emissions and secondary inorganic aerosols each made up 11.7% of the load. Wood burning rose to 10.7%, waste burning reached 7.7%, and mixed combustion accounted for 5.1%. Mixed or unresolved biofuel contributed 3.3%, and mineral dust and ash stood at 1.5%. Delhi's average 24-hour Air Quality Index improved slightly to 299 on Tuesday in the poor category, before climbing to 312 on Wednesday to enter the very poor category.

Context

Air quality in the national capital regularly worsens during the winter months due to a combination of local emissions, waste burning, vehicular exhaust, and seasonal weather patterns. Source-apportionment models help scientists understand which specific sectors contribute most to the smog at any given time, guiding local policy responses.