New Delhi, Jun 25 (IANS): The Central Pollution Control Board (CPCB) on Thursday reviewed the preparedness of authorities in Delhi and surrounding regions to deal with air pollution problem in the winter season.

CPCB Chairperson Ravi Shankar Prasad reviewed the preparedness of state Pollution Control Boards, Municipal Corporations, and other agencies. "The agencies were directed to submit a detailed Action Plan by the first week of July," a CPCB statement said.

Even though the national capital records high-level of air pollution throughout the year, the air quality especially becomes toxic in winters. The sky-rocketing levels are attributed to crop residue burning and vehicular pollution.

Each winter, a grey noxious smog envelops the capital city and other cities in the north. On an average day, PM 2.5, which is too small to be filtered out of the body, mounts to the "very poor" category.

According to a report by the CPCB and Ministry of Environment, Forests and Climate Change, cold, dry air, and ground based inversion with low wind conditions are responsible for increasing concentration of pollutants in winters.

"Moreover, dense smog formation during winter months has also been witnessed in Delhi, the reason of which is vehicular pollution as well as the prevailing meteorological conditions in the months of December and January. Similarly, wind patterns also affect the weather conditions," the report accessed by IANS stated.

Due to deteriorating AQI in 2019, schools were shut down, and the Delhi government's odd-even scheme was also brought into force.