‘Pollution inches back up, air may get worse’: IMD

Central Pollution Control Board (CPCB) data showed that on Friday, Delhi’s overall air quality index (AQI) settled at 339, in the ‘very poor’ category, a day after improving to 314.

After two days of minor respite from ‘severe’ levels of pollution, the air quality in Delhi started dropped again on Friday as wind direction changed from easterly to north-westerly, bringing in stubble burning smoke from states such as Punjab and Haryana.

Street vendors push their tri-cycle carts amid an atmosphere shrouded in smog, in New Delhi. (PTI)

Central Pollution Control Board (CPCB) data showed that on Friday, Delhi’s overall air quality index (AQI) settled at 339, in the ‘very poor’ category, a day after improving to 314.

The AQI was in the ‘severe’ zone for six days, starting November 5. Delhi got minor relief on Wednesday and Thursday, when the AQI improved to the ‘very poor’ category after winds shifted direction, blowing in from the east.

VK Soni, head of IMD’s environment monitoring research centre, said after two days of winds from the eastern side of Delhi, the city started receiving north-westerly winds from early Friday. This increased the contribution of stubble smoke from Punjab and Haryana to 14% from 3% a day before.

“The wind speed also slowed down, which added to the pollution concentrations today (Friday),” Soni said.

Kuldeep Srivastava, head of IMD’s regional weather forecasting centre, said the average wind speed on Friday was around 8kmph, which led to an increase in the pollution levels. He said from Diwali afternoon, the wind speed will dip to nearly 6kmph.

“From Diwali evening(Saturday), the air quality is likely to start deteriorating. However, from Sunday night, the wind direction is expected to change again to easterly and there is a possibility of light rain. The pollution particles stick to the moisture in the air and settle closer to the ground, making the air quality worse,” Srivastava said.

The IMD forecast said from Monday, the wind speed is likely to improve, which again could improve the air quality.

The Union ministry of earth sciences’ air quality monitoring centre, System of Air Quality and Weather Forecasting and Research (Safar), said the change of wind direction led to an increase in the contribution of stubble burning smoke from Punjab and Haryana.

On Thursday, the share of stubble smoke on Delhi’s PM 2.5 levels (ultrafine particulate matter with diameter less than 2.5 micrometres) was 3%, which increased to 14% on Saturday.

“The overall air quality of Delhi is in the very poor category. Air quality is predicted to deteriorate and remain in the higher end of very poor levels in the absence of any additional emissions due to fireworks during the Diwali period. The stubble burning-induced impact in AQI is expected to increase from negligible to moderate for the next two days,” the Safar air quality analysis read.