The first half of October witnessed better air because of the extended rains, but the second half of the month saw ‘poor’ and ‘very poor’ days that made the average AQI deteriorate, experts said. Local pollution sources like garbage burning and road dust, as well as the weather (lack of ventilation due to low wind speed) combined to make pollution levels worse in the month this year, they said.
This October, the city saw six ‘very poor’ days, 11 ‘poor’ days, eight ‘moderate’, two ‘satisfactory’ and four ‘good’ days. Last year, there were two ‘very poor’ days, five ‘poor’ days, 17 ‘moderate’ days, six ‘satisfactory’ days and one ‘good’ day.
While emission sources for a defined area remain more or less the same throughout the year, the concentration varies with the season. Air quality in north India is usually problematic after monsoon, which is a transition phase, because of lowering of wind speed and temperature. Historically, wind speed of 2m/s or below can lead to a dangerous situation in terms of pollutants, experts said.
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“This October had less rain compared to last October. Also, Diwali was early this year which also contributed to the month’s overall AQI. Last year, Diwali was on November 4, so the Diwali pollutants were not included in the October AQI,” said Shubhansh Tiwari, a research associate at Amity Centre for Air Pollution Control.
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’, and 401 and 500 ‘severe’. According to guidelines issued by the Central Pollution Control Board, when AQI is in the ‘moderate’ category, there can be breathing discomfort to the people with asthma and lung or heart disease.
Meanwhile, the city’s AQI on Monday was ‘very poor’ at 376. While the Sector 51 monitoring station reported ‘severe’ AQI at 415, it was ‘very poor’ at Vikas Sadan (327) and Teri Gram (396). Data was unavailable at Gwalpahari station.
Officials from the Haryana State Pollution Control Board (HSPCB) pointed out that suspension of road dust due to vehicular traffic is of special concern as dust is a carrier of toxins from combustion sources and can be harmful. “The strategy to address this problem has to be diverse and not limited to only road cleaning and sweeping. It is also created by mismanaged urban construction and roads. Broken and unpaved roads are the major cause of dust pollution in the city,” said Sandeep Singh, the HSPCB regional officer for Gurgaon.