Air quality deteriorates in May as public mobility increases

Air quality in the city deteriorated in May, with an average daily reading of 143 on the air quality index (AQI), according to data from the Central Pollution Control

Air quality in the city deteriorated in May, with an average daily reading of 143 on the air quality index (AQI), according to data from the Central Pollution Control Board (CPCB). This was up from an average AQI value of 110 in April, and 113 in March. Experts said they expected the uptick in pollution, as the past month has seen an increase in vehicular movement during phases three and four of the ongoing nationwide lockdown to curb the spread of the Covid-19 pandemic.

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The deterioration of air quality between April and May is also atypical, experts said. “Usually, with a rise in temperature as the summer progresses, air quality tends to improve in May. This year we are seeing the reverse take place. But on the whole, air quality is still better than it was during the same time last year,” Sachin Panwar, a city-based air quality scientist, said.

Another indicator that points to increasing vehicular emissions as the cause for Gurugram’s deteriorating air quality is a spike in atmospheric ozone, which was recorded as a primary pollutant on 22 days in May, as per the CPCB’s daily AQI bulletin for the city. Ozone is a composite, or secondary pollutant, formed due to chemical reactions undergone by other pollutants, such as sulphur oxides and nitrogen oxides.

“NOx are directly emitted by vehicles. The formation of ground-level ozone implies that primary pollutants, in this case, nitrogen oxides, are being emitted into the atmosphere,” Panwar explained.

This is also reflected in data from Gurugram’s four air quality monitors. For example, on April 30, the average concentration of NOx in the city’s air was 8 parts per billion (ppb), down from 14ppb on April 1. In May, however, the concentration of NOx in city air shot up, exceeding over 100ppb on several days of the month.

Further evidence of increased public mobility can be seen in data published by Google. Between April 26 and May 25 in Haryana, public movement to retail and recreational spaces increased by 24%, while visits to transit stations increased by 15%, and visits to pharmacies, food markets and grocery stores increased by 38%. Visits to workplaces also increased by 6% during the same time frame, while visits to parks and public spaces increased by 8%.

Despite repeated calls and texts, Haryana State Pollution Control Board (HSPCB) officials were not available for comment.