For the first time in two years, Delhi has seen two days of ‘good’ air quality in July, according to a report by the Central Pollution Control Board (CPCB). Moreover, not a single day in July saw ‘poor’ air quality, a feat that has not been replicated in any month of the last 25, save August 2016. These classifications are part of a 6-grade, colour-coded Air Quality Index (AQI) that the government uses to rate air quality.
Officials attribute July’s salubrious air to a “combination” of above-normal rains and the various steps taken in the aftermath of the Graded Action Plan — notified this January — whereby municipal and State authorities must undertake a series of steps if particulate matter pollution exceeds 300g/m3, i.e., ‘severe’ pollution.
While the peak monsoon months of July and August typically see an improvement in air quality — because monsoon winds and rain settle noxious particles to the ground — the average air quality in these months is mostly only ‘moderately’ good, or still not absolutely safe for asthmatics or those with underlying respiratory problems. Delhi gets monsoon rains only around mid-July and has got 25% less monsoon rainfall than what is normal for June 1 to August 3. Two weeks of June and one in July, however, saw excessively heavy rainfall.
“There is no single factor but weather has played a role. The real test, however, will be during the winter months,” said D. Saha, who heads air quality monitoring at the CPCB. Since the organisation began issuing colour-coded air quality reports only since May 2015, Mr. Saha said he was not sure if previous Julys had seen air quality improve to the levels observed last month.
