Slow wind may worsen bad air today, says Met

NEW DELHI: The Capital’s Air Quality Index (AQI) stayed in the “very poor” category on Sunday, with an average 24-hour reading of 303, according to the Central Pollution Control Board’s (CPCB) national bulletin released at 4pm every day.

The AQI reading was 303 (very poor) on Saturday too.

While strong northwesterly winds blowing towards the Capital brought stubble fire emissions from Punjab, Delhi witnessed strong surface winds during the day, which helped disperse pollutants.

VK Soni, scientist at India Meteorological Department (IMD) and part of Commission for Air Quality Management in National Capital Region and Adjoining Areas, said despite impact of stubble emissions, the AQI did not deteriorate on Sunday, as wind speed ranged from 6-20kmph during the day. “This negated the impact of the farm fires and the strong local winds ensured pollutants did not accumulate,” he said.

Agencies on Sunday forecast that Delhi’s AQI will deteriorate slightly on Monday, with local wind speeds dropping slightly.

Soni said while winds are expected to become calm once again in the early hours of Monday, the wind direction is expected to be variable, thereby reducing the impact of stubble burning. “A western disturbance is expected in northern India again and that will bring some moisture to Delhincr. Moisture and low wind speed will act negatively, but a variable wind direction will ensure stubble contribution to Delhi’s pollution is low,” he said, adding wind speed over Delhi will once again pick up from November 15-18.

According to the System of Air Quality and Weather Forecasting And Research (Safar), under the ministry of earth sciences, the contribution of stubble burning to Delhi’s PM 2.5 concentration was 24% on Sunday, up from a contribution of 17% on Saturday. The highest single-day contribution this season was 34%, recorded on November 3.

Punjab, Haryana and Uttar Pradesh recorded a total of 2,409 farm fires on Sunday. The combined total was 2,602 fires on Saturday. Of these, Punjab contributed 2,175 fires on Sunday and 2,467 fires to the combined count on Saturday.

“Despite a moderate stubble emission share due to favourable upper-level wind flow (blowing from northwest), the AQI is likely to remain within ‘very poor’ or in the upper end of the ‘poor’ category on November 14 and 15 due to efficient dispersion of pollutants by local weather,” said Safar.

Forecasts by the Early Warning System (EWS) for Delhi, which the CAQM uses, also show AQI is likely to remain “very poor” on November 14 and 15, before improving to the “poor” category once again on November 16.

“The outlook for the subsequent six days shows the air quality is likely to remain largely between ‘poor’ and ‘very poor’ category,” EWS said.