March air was ‘moderate’, but pollution dipped sharply since March 25

In March, the city recorded an average daily air quality index (AQI) value of 113, implying that it was experiencing largely ‘moderate’ air quality over the past

In March, the city recorded an average daily air quality index (AQI) value of 113, implying that it was experiencing largely ‘moderate’ air quality over the past month. However, the city has seen a sharp dip in pollution levels since March 25, when a nationwide lockdown to contain the outbreak of the coronavirus disease (Covid-19) was enforced. Since the lockdown began, most vehicles have been off the streets and Gurugram’s air quality has ranged between 42 to 77, in terms of its daily average AQI value, while levels of particulate matter have remained within nationally prescribed ‘safe’ limits.

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The city’s average AQI value for February, as per Central Pollution Control Board data, was 190 (also in the ‘moderate’ category). “The air quality has remained in the ‘moderate’ category over February and March, but with a slight improvement due to the lockdown, as well as the rainfall earlier in the month. We will see an even sharper improvement between March and April, as the lockdown continues, mainly due to the shutdown of industries and lack of vehicles on roads,” Sachin Panwar, a city-based air quality scientist, said.

Morning and evening peaks in the level of PM 2.5 (due to daily rush-hour commutes causing heavy traffic movement) have also flattened in the days since the lockdown came into force, according to an analysis by the Centre for Science and Environment (CSE). Data from three of Gurugram’s air quality monitors—at Gwal Pahadi, Sector 51, and Vikas Sadan—confirms that this is the case. All three monitors show PM2.5 to be at an average value between 40 and 50µg/m³ per day over the past 10 days, which is within the national safe limit of 60µg/m³.

These monitors also show a sharp reduction in the levels of nitrogen dioxide (NO2), which can be directly attributed to the absence of vehicles on city streets, and closure of non-essential industries, both of which burn fuel and are major sources of NO2 in the atmosphere. “This analysis brings out the pronounced effect of traffic on hourly pollution trend and daily exposures to toxic vehicular pollution. With traffic minimised, hourly trends plummet. This is sharply evident in NO2 trends,” the CSE said in its analysis.