Farm fires rage, but favourable wind helps Delhi’s air

Delhi’s air on Tuesday deteriorated and touched the outer margins of the ‘very poor’ category.

Delhi’s air on Tuesday deteriorated and touched the outer margins of the ‘very poor’ category.

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Even though farm fires continued raging in Punjab and Haryana, with more than 3,000 cases being spotted on Tuesday again, a change in the wind direction helped keep the share of stubble fumes on the city’s pollution under check.

Central Pollution Control Board (CPCB) data shows that the overall air quality index of Delhi was 302, in the ‘very poor’ category. On Monday, the city’s AQI had improved to ‘poor’ category, at 293.

Scientists at the India Meteorological Department (IMD) said that though the city choked, high wind speed helped keep the situation from deteriorating.

VK Soni, head of IMD’s environment monitoring research centre, said that the AQI levels are likely to remain in the early end of ‘very poor’ category till November 5, after which there could be a marginal deterioration again.

“On Tuesday, in the morning, there was a spike in the pollution levels but by noon the wind speed picked up and the air cleared up. The wind speed post-noon was around 15kmph, which helped disperse the pollution,” said Soni.

“The boundary layer wind direction became unfavourable (south-westerly on Tuesday morning) after a long spell, fire-related stubble burning share in PM2.5 (ultrafine particulate matter with diameter less than 2.5 micrometers) in Delhi’s air has significantly decreased and is estimated as 10% for Tuesday. Today (Tuesday) is a typical example of high fire count and low impact in Delhi’s air, due to unfavourable transport level winds demonstrating as to how meteorology can play a decisive role,” read the Safar air quality analysis.