Air pollution: Delhi AQI slips to ‘very poor’ category; firecrackers on Diwali could worsen air quality, forecast suggests

Delhi’s overall Air Quality Index (AQI) declined to the ‘very poor’ category today, the Centre-run System of Air Quality and Weather Forecasting and Research (SAFAR) said. This is the first time this season that the AQI in the national capital has declined to the category.

The Indian Meteorological Department (IMD) had earlier warned that Delhi’s air quality is likely to remain in the lower spectrums of the ‘poor’ to ‘very poor’ categories on Tuesday and Wednesday. On Thursday, the air quality is likely to decline to the lower end of the ‘very poor’ category.

PM2.5 and PM10 concentrations today stood at 252 in the ‘poor’ and 131 in the ‘very poor’ category, respectively.

The air quality is likely to remain ‘very poor’ on Saturday and Sunday, the IMD said, adding PM2.5 would be the predominant pollutant.

The decline comes after Delhi witnessed its cleanest October air since at least 2018. During last month, the average AQI in the city-state was recorded at 173 — down from 265 last year.

Experts attributed the improvement to record monsoon rainfall. The national capital also witnessed record October rainfall due to the presence of a western disturbance and the delayed withdrawal of the monsoon current.

One of the reasons being attributed to the decline in Delhi’s AQI is the rise in farm fire incidents in Haryana and Punjab. After witnessing a decline around October 24 and 25 following widespread rainfall in parts of India’s northwest, active fire events have risen in Haryana and Punjab over the past few days.

The situation is likely to get worse on Diwali even if there is no emission from firecrackers, SAFAR researchers noted. The presence of firecracker pollutants will lead to further deterioration.

Delhi’s PM2.5 levels are expected to hover in the upper band of the ‘poor’ category under a “zero firecracker emission scenario” between Thursday and Saturday. When additional emissions from firecrackers are taken into account, even 50% of the emission from 2019 could push the index to the ‘severe’ category from Thursday night, the SAFAR forecast said.