Rains improve Delhi AQI to moderate category from severe

New Delhi: A day after rains lashed Delhi and NCR, the pollution level reduced significantly to the moderate category with AQI hovering between 120-150 in several parts of the capital on Tuesday.

Besides rains, favourable wind speed under the influence of a western disturbance affecting northwest India provided much needed relief to people from choking air quality.

The Safdarjung Observatory, the national capital's primary weather station, recorded 7.2 mm of rainfall till 8:30 pm on Monday.

The wind speed improved to 20 kilometres per hour, aiding the dispersion of pollutants, an official at the India Meteorological Department said.

Delhi's air quality index (AQI) stood at 395 at 4 pm on Monday.

The 24-hour average AQI, recorded at 4 pm every day, was 395 on Sunday, 389 on Saturday, 415 on Friday, 390 on Thursday, 394 on Wednesday, 365 on Tuesday, 348 on Monday and 301 on November 19.

An AQI between zero and 50 is considered 'good', 51 and 100 'satisfactory', 101 and 200 'moderate', 201 and 300 'poor', 301 and 400 'very poor', 401 and 450 'severe' and above 450 'severe-plus'.  Earlier on Monday, a thick layer of smog blanketed Delhi, reducing visibility to just 600 metres at the Safdarjung Observatory. The visibility was 800 metres at the Indira Gandhi International Airport.

The national capital recorded 12 severe air quality days this November so far.

The city recorded just three severe air quality days in November last year, while it experienced 12 such days in 2021, the maximum in the month since the Central Pollution Control Board (CPCB) began monitoring.

There were nine such days in November 2020, seven in 2019; five in 2018; seven in 2017; 10 in 2016, and six in 2015, according to CPCB.

According to a joint project by the Delhi government and the Indian Institute of Technology-Kanpur, biomass burning was the top reason for Delhi's foul air, contributing 31 to 51 per cent to the capital's air pollution in the last few days.