Despite the average wind speed of 15-16 km / h, the air quality in Delhi remained poor on Thursday for the second day in a row. According to the daily bulletin of the Central Pollution Control Board, Delhi posted an AQI value of 208, putting it in the ‘poor’ area.
Experts said that although faster winds play an important role in dispersing pollutants, it is not helping in Delhi’s case as the wind speed is not constant throughout the day. Also, the wind direction is not helpful as it blows from the northwest bringing particulate matter (PM2.5 and PM10, one of the main pollutants in Delhi’s air) from Haryana and Punjab, where agricultural fires are raging, they said. .
According to scientists from the Indian Meteorological Department (IMD), the wind speed decreases between the afternoon and early morning. They also said that currently northwesterly winds are bringing fumes from burning crop stubble in Haryana and Punjab, which according to the Delhi government is one of the major contributors of particulate matter to Delhi’s air.
“These pollutants cannot be dispersed as much with the daytime wind alone, since the winds calm down from the afternoon until the early hours of the morning. The duration during which the wind speed is good is very short. In addition, with a drop in mercury, the ventilation rate (the ability of the atmosphere to dilute and disperse pollutants in a region) has also become slightly low, ”said Kuldeep Srivastava, head of the regional weather forecast center of the IM D.
On Wednesday, Delhi’s air sank in the “poor” area for the first time since June 28. Government agencies warned that the air quality in Delhi could deteriorate further over the next two days even if it remains in the “poor” area. According to the CPCB, prolonged exposure to poor air can cause respiratory discomfort in most people.
According to the Weather and Air Quality Research and Forecasting System (Safar), the central government’s air quality monitoring and forecasting wing, being PM 2.5 the lead pollutant is characteristic of winter. “The forecast for the AQI is at the upper end of the moderate to poor category on Friday. However, it is expected to improve thereafter to return to the moderate category. On Wednesday a gradual increase in stubble fires was observed around Punjab, Haryana and neighboring border regions. The boundary layer wind direction and speed are favorable for the transport of pollutants into Delhi at present, but a change in wind direction is likely from 11 October, which is likely to help improve the air quality, ”stated the Safar newsletter.
According to Safar, the fire count in the northwest region on October 7 was 399.
IMD’s Srivastava also said wind speeds in the region are likely to improve by Sunday.
“Air quality may improve slightly from October 11-12 due to likely thunderous developments in the region. The wind direction will also change to the southeast during this time. However, this pattern will change as of October 15, with the return of northwesterly winds and a decrease in both day and night temperatures, ”said Srivastava.
On Thursday, the low temperature was set at 19.1 degrees Celsius, two levels below normal, while the maximum was set at 35.6 degrees, two levels above normal.
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