On Wednesday, air quality in New Delhi dropped to "severe" due to a drop in temperature and wind speed that trapped pollutants in the atmosphere, provoking health warnings from the government for the 12th time in two months.

On Tuesday, the air quality index crossed 400 which indicated a level of pollution that affects healthy people and have serious impacts on those with existing diseases, as per the government guidance. The index measures small particulate matter of 2.5 microns or less in diameter (PM2.5) that penetrates the lungs and enter the blood system. Prolonged exposure to such particles can contribute to the risk of developing cardiovascular and respiratory diseases, also lung cancer, according to the World Health Organization.

The Ministry of Health said that those who are vulnerable to health risks should avoid outdoor physical activities when the air quality index is between poor to severe.

Air quality levels in Delhi have progressedfrom "very poor" to "severe" during the last two weeks due to cool temperatures. Schools were closed for four days in November when the index had climbed past 500.

Government-run monitor SAFAR has predicted rain in the next two days and have hoped that showers would bring down pollution levels.

Source: ET Healthworld