The air quality in the national capital and its surroundings turned "severe" on Thursday with humidity trapping particulate matter added to stubble burning by Punjab and Haryana farmers.
While restrictions on construction, industries and garbage burning came in to force from Thursday, more bans were being considered including one on entry of trucks and the odd-even vehicle rationing scheme.
Stubble burning in Punjab and Haryana was contributing to 28 to 30 per cent of the city's pollution, Polash Mukherjee, Senior Research Associate with the Centre for Science and Environment (CSE) told IANS.
With negligible wind over Delhi, pollutants were trapped due to rise in humidity early on Thursday when the air quality was put as "very poor".
The central government's System of Air Quality and Weather Forecasting And Research (SAFAR) advised people to avoid all outdoor physical activities and those with asthma to keep relief medication handy.
At 11 a.m., the Air Quality Index of Delhi was 394. However, with sharp rise in major pollutants and Delhi's PM2.5 at 247 and PM10 at 448 microgrammes per cubic meters, the quality turned severe as it crossed the 400 mark.
Across the National Capital Region, the average PM2.5 and PM10 concentrations were 241 and 431 units, respectively.
For air quality to be severe, the PM2.5 must be between 250 and 300 or PM10 must be between 430 and 500, according to Central Pollution Control Board (CPCB).
The first day of restriction in Delhi was imposed on Thursday after "severe-plus" air quality was measured with the AQI crossing the 500 mark.
Chandni Chowk, Dwarka sub-city, Rohini, R.K. Puram, Narela and Punjabi Bagh were among the 18 regions, out of 36, which reeled under severe air quality with PM2.5 above 400 units.
In Gurugram, Faridabad, Noida and Greater Noida it was already "severe" by 11 a.m.
Both PM2.5 and 10 get into the lungs and cause cardiovascular and respiratory diseases, but PM2.5 is more dangerous because it mixes with the blood stream.
The Central Pollution Control Board (CPCB) had said high moisture level in the air has trapped emissions from local sources and hanging low over the city in the absence of wind. Air from neighbouring Punjab and Haryana, where paddy stubble burning is in full swing, is not entering the city as of now. When it starts, the situation is expected to deteriorate further, claimed officials from CPCB.
(With inputs from IANS)
