Experts said to check further deterioration authorities must act quickly against all emission sources. As per System of Air Quality and Weather Forecasting And Research (Safar) extended outlook, further deterioration in AQI of Delhi may start from the fourth week of October.
As the AQI crossed the 300-mark, the AQI plunged to the very poor category for first time this season, two times higher than safe levels.
PM2.5 has deteriorated sharply to 131 in the very poor category. The PM 10 score at 241 is much better in the moderate category, according to pollution readings by Safar India.
Experts said the PM 2.5 pollutants are rising dangerously.
Vivek Chattopadhyaya, Programme Manager, Air Pollution Control Unit, Centre for Science and Environment (CSE) said the air quality is deteriorating fast due to stagnating weather and has reached to very poor category on hourly basis.
As per the CPCB's monitoring portal, average PM2.5 at noon on Wednesday was 134.6 microgram per cubic metre which is about two times higher than the safe level for 24 hours (60 microgramme per cubic metre), he added.
"To prevent further deterioration authorities must gear up to intensify their action on all emission sources," he added.
The late monsoon withdrawal is not good for air quality in North India as the time progresses towards winter. During the fourth week of October, the temperature will also see a dip, Safar said.
As per Central Pollution Control Board (CPCB), very poor category air can cause respiratory illness on prolonged exposure.
( With inputs from IANS )