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As monsoon ends, Delhi’s air quality turns ‘poor’

The Supreme Court-appointed body Environment Pollution (Prevention and Control) Authority (EPCA) has called for a meeting on Friday to explore possible solutions to control local dust.

delhi Updated: Sep 30, 2018 11:09 IST
HT Correspondent
HT Correspondent
Hindustan Times, New Delhi
Delhi air,air pollution,air quality
The air quality of Delhi started deteriorating since Thursday night and by Friday the average air quality of the city was standing at 197, just four notches below the ‘poor’ zone.(HT File PHOTO)

The air quality in the national capital turned ‘poor’ on Saturday, after a gap of almost two months. The last time the city’s air quality had entered the ‘poor’ zone was in the first week of August when the winds brought in huge amounts of dust particles from Oman.

The situation in Gurgaon and Greater Noida was worse, with the air quality levels on the brink of being ‘very poor’.

SAFAR, which works under the ministry of earth sciences and is India’s official pollution forecasting system, has forecast that pollution levels are likely to increase over the next two days.

The Supreme Court-appointed body Environment Pollution (Prevention and Control) Authority (EPCA) has called for a meeting on Friday to explore possible solutions to control local dust.

The air quality of Delhi started deteriorating since Thursday night and by Friday the average air quality of the city was standing at 197, just four notches below the ‘poor’ zone.

“On Saturday, the AQI in Delhi was recorded to be 219, which is ‘poor’ according to the National Air Quality Index. Pollution levels started increasing soon after rains stopped in the city. The AQI of Gurgaon and Greater Noida were 298 and 299 respectively,” said a senior official of the Central Pollution Control Board (CPCB).

On a scale of 0 – 500, an AQI value between 201 and 300 is considered to be ‘poor’ while a value between 301 and 400 is considered to be ‘very poor’. Beyond 400 it is tagged as ‘severe’.

In the winter of 2017,- Delhi encountered a week-long spell of smog when the AQI hit a peak of 486 on November 9.

CPCB scientists had then blamed it on incoming dust particles from west Asia.

Experts said that the sudden spike in pollution levels this time is because of the rise in natural and coarse dust particles, the levels of which have shot up alarmingly since September 24 — the day when Delhi received its last monsoon rain.

“From around 39ug/m3 at 6pm on September 24, the level of PM10 (coarse dust particles) has shot up to 254ug/m3 around the same time on Saturday. It is now more than 2.5 times above the daily permissible limits of 100ug/m3,” said the CPCB official.

The level of PM2.5 (ultrafine particles that comes out from vehicles, industries and garbage burning) has also risen, but not to that extent. PM2.5 level was registered to be 101 ug/m3 at 6 pm on Saturday. The permissible limit is 60ug/m3.

“Such deterioration of air quality is normal during this time of the year when southeasterly winds of the monsoon season gives way to northwesterly winds before winter. During this time the air becomes dry and its velocity is almost zero. As a result, local pollutants are not getting dispersed. This will continue till wind speed picks up,” said D Saha, former head of the CPCB’s air quality laboratory.

“We are gradually entering the danger zone because the rains have ended and winter is approaching. We have to take stock of the preparedness before the Graded Response Action Plan comes into play from October 15 and tougher measures would have to be implemented to keep situations under control,” said Anumita Roy Chowdhury, executive director (research and advocacy) at Centre for Science and Environment.

First Published: Sep 30, 2018 08:58 IST