Rain deficit led to ‘smog episodes’ and ‘poor AQI’ in Delhi, says CSE’s report

This year Delhi recorded a 64 percent deficit in rainfall in October and a 33 percent deficit in September, according to the India Meteorological Department (IMD).

CSE’s report flagged the sudden increase and rapid build of PM levels in November while explaining it said, “On November 2, PM 2.5 levels in Delhi crossed 300 µg/m3 or “severe+” level for the first time this season. It was a very sudden escalation as the level rose a staggering 68 percent within 24 hours. In the last five years, the overall trend shows PM2.5 levels started to rise steadily from the start of October. However, this year, the PM2.5 levels started to rise from the middle of September onwards.”

While the concentration of nitrogen dioxide, mostly from vehicles, is rising, particulate matter levels are also high. On November 2, the average NO2 level was 58.4 µg/m3, up from 28.6 µg/m3 on October 24.

Certain high-traffic locations in the city have reported NO2 levels which are three to four times higher than the 24-hour standard, the CSE report said. The 24-hour standard for NO2 is 80 µg/m3. ITO was found to be the most polluted location for NO2 with a level of 219 µg/m3, followed by Nehru Nagar at a level of 122 µg/m3, and Siri Fort at 95 µg/m3.

The report also noted that despite the implementation of action plans at the 13 pollution hotspots in the city, areas like Mundka and Anand Vihar, remain the most polluted in the city, while newer hotspots like Nehru Nagar are emerging now.

On Monday, the AQI in Delhi remained in the ‘severe’ category for the fifth consecutive day, with an average AQI of 436 at 8 am.