The air quality fell to “very poor” levels on Thursday and is likely to worsen over the next few days, weather officials said, warning of a deterioration in conditions in the coming days – particularly after Diwali.
The daily air quality index (AQI) – calculated as a 24-hour average till 4pm – was at 311 on Thursday, a level last seen on October 16 before a pick-up in wind speeds helped keep air pollution down.
According to a Delhi environment department official, easterly winds will cease from Sunday – the day of Diwali – and will be replaced by northwesterly winds, which could bring in pollutants from farm fires in the neighbouring states of Punjab and Haryana.
The change in wind direction will also cause a drop in temperature, and, along with residual moisture, could create fog.
“This could turn matters worse, as the calm winds, fog and dip in temperature could help trap the smoke from stubble burning, firecrackers and other local emissions,” this official added, asking not to be named.
The warning prompted the task-force headed by the Central Pollution Control Board (CPCB) to recommend a slew of pre-emptive measures such as banning construction activity between 6pm and 6am, and shutting down coal-powered industries (except power plants) from October 26 to October 30 in Delhi and neighbouring satellite towns.
A final call would be taken by the Environment Pollution (Prevention and Control) Authority. “We will take the call as soon as we receive the recommendations,” said Sunita Narain, member of EPCA.
“The next few days will be challenging and in addition to intense action by agencies, additional preventive measures may be required to check the deteriorating air quality,” said Prashant Gargava, member secretary of CPCB, who headed the task-force meeting.
By 7pm on Thursday, the concentration of PM10 (the coarser dust particles) was already three times the permissible limit of 100ug/m3. The concentration of PM2.5 – ultra fine particles that can reach deep within lungs – was more than twice the safe limits of 60ug/m3.
The minimum temperature, which was hovering at 17.7°C on Thursday, is predicted to drop to around 15°C on Diwali and post-Diwali day. The maximum temperature on Thursday was 32.1 degrees Celsius.
