Delhi recorded AQI of 41 on Monday, lowest since records kept

New Delhi: Delhi on Monday recorded an air quality index (AQI) of 41 -- the lowest since 2015 since when AQI monitoring records are being maintained in the national capital.

According to the Central Pollution Control Board’s (CPCB) 4pm bulletin, the average AQI in Delhi was 41 in the “good” category. This was also the fourth “good” air day recorded over a month since 2015.

Board officials said the good air quality was because of a combination of factors, including incessant rainfall, good winds and already reduced levels of pollution during the lockdown months. The CPCB data says while 2015 and 2016 did not record any “good” days, two were recorded in 2017 on July 30 and 31, with AQI readings of 43 and 47, respectively.

The year 2018 did not record any “good” air day as well. In 2019, two consecutive ‘days were recorded on August 18 and 19, with AQI readings of 49 on both of those days.

So far, five “good” air days have been recorded this year.

“There were two good air days in 2017 followed by two in 2019. This year we already have five good air days, and 41 is the lowest AQI. Its good news for residents,” said a senior CPCB official who asked not to be named.

The first such day was on March 28 (during the first week of the Covid-19-induced lockdown) with an AQI reading of 45.

Then on August 13, after heavy rain, the AQI was recorded at 50. On August 20, again, when Delhi received “very heavy” rainfall, the AQI was again 50. On August 24, an AQI of 45 was recorded.

On a scale of 0-500, a value of 0-50, the air quality is considered good (minimal health risk), 51 -100 is satisfactory (minor discomfort to sensitive people), 100-200 is moderate (breathing discomfort to people with lungs and heart disease), 200-300 is poor (breathing discomfort to most people on prolonged exposure), 300-400 is very poor (respiratory illness on prolonged exposure) and 400-500 is severe (affects healthy people and seriously impacts those with existing diseases).

“Usually, the monsoon months are cleaner than the rest of the year. This month, as well as this year so far, has been exceptionally good because of intense and continuous rainfall as well as good winds over the past few days, which cleansed the air of all the pollutants. Besides, the overall pollution levels have been low as an impact of the lockdown imposed to curb Covid,” said a second senior CPCB official who also asked not to be named.

HT had earlier reported that this August recorded only “good” and “satisfactory” days with not a single “poor” air quality day being recorded.

According to officials in the India Meteorological Department (IMD), with incessant rainfall over the past two weeks, this August has been the second ‘wettest’ in 12 years. The Capital received 364.8 mm rainfall this August, 30% above the normal mark.

Vivek Chattopadhyay, senior program manager, clean air programme, Centre for Science and Environment (CSE) said, “The air quality analysis for this year in comparison to previous years reveals the air has been much cleaner because of a combination of factors. The good meteorological conditions combined with low emission because of the lockdown and reduced economic activity even after the reopening together resulted in good air.”