What’s polluting Delhi’s air? City stays in ‘very poor’ zone for third straight day

Delhi’s air quality continued to remain in the ‘very poor’ category on Wednesday, two days after Diwali. With the air quality index (AQI) being recorded at 353, the figure was marginally higher than Tuesday’s reading of 351, as per Central Pollution Control Board (CPCB) data.

Source apportionment data from the Decision Support System (DSS) for air quality management shows that the mix of pollution sources impacting Delhi has changed since Diwali on October 20.

At 36.06% of the total emissions, the DSS attributed the highest pollution load on Wednesday to the “others” category, which stands for unaccounted sources. The category broadly covers unaccounted or out-of-inventory sources beyond the study radius used by the DSS emission inventory.

According to DSS data, the transport sector was the second most significant contributor to Delhi’s pollution at 15.77%. While the energy sector contributed 1.61%, construction activities accounted for 2.18%, and waste burning 1.47% to the pollution.

Meanwhile, the industrial contribution from Delhi and peripheral NCR areas stood at 3.49%, while stubble burning contributed 1.62% to Delhi’s PM2.5 load on Wednesday. The share of stubble burning had risen to 2.62% on October 17, before dipping due to changes in wind direction and speed. According to experts, cases of stubble burning are expected to rise again as northwesterly winds have started carrying emissions from Punjab and Haryana to Delhi.

The DSS data further shows that Ghaziabad (5.28%), Jhajjar (5.11%), Gautam Buddha Nagar (4.01%), Gurgaon (2.08%), Bulandshahr (1.68%), and Panipat (0.86%) added to Delhi’s pollution load. In all, contributions from neighbouring industrial and urban clusters accounted for nearly one-fifth of the total pollution in Delhi.

Sunil Dahiya, lead analyst and founder of think-tank Envirocatalysts pointed out that the “others” category likely includes emissions from power plants, industries, and rural burning in Punjab and Haryana, which the DSS inventory doesn’t dynamically capture.

“The emission inventory is not dynamic. Anything beyond the defined study area is clubbed as ‘others’. If we don’t update the inventory, it becomes difficult to take targeted actions,” he added.