The air pollution level in Indian capital city New Delhi and outskirts of the national capital region (NCR) Wednesday became severe, government agency said.
According to the Central Pollution Control Board (CPCB), the overall air quality index (AQI) in the city remained in severe category at 402.
"The AQI in Delhi at 10:00 a.m. (local time) today was recorded at 402," data released by CPCB said. "The prominent pollutants are PM 2.5 and PM 10, and air quality is in the severe level category."
For the past four days, people in the Indian capital have been breathing very poor air.
As per CPCB, AQI between 0-50 is considered "good," between 51-100 "satisfactory," between 101-200 "moderate," between 201-300 "poor," between 301-400 "very poor," and between 401-500 "severe" and beyond 500 is severe plus emergency.
Health officials say deterioration in air quality causes respiratory illness on prolonged exposure and people should stop outdoor activities in early morning and after sunset time.
People should also avoid prolonged or heavy exertion and use masks known as N-95 or P-100 respirators while going out to minimize effect, experts said.
System of Air Quality and Weather Forecasting And Research (SAFAR), an institute monitoring air pollution said an improvement in AQI is expected by Thursday.
"By Dec. 13, further improvement in AQI is forecast towards the lower end of the poor to the moderate category. Only a few biomass fire counts have been observed and no significant biomass fire PM 2.5 contribution is expecting for the coming days," SAFAR said.
"The approaching western disturbance (WD) is likely to affect northwest India by Dec. 12. Significant improvement in AQI through increased ventilation and washout due to rainfall is expecting by Dec. 13. After the WD, increased moisture can lead to foggy conditions."
Last month air quality in the city remained in a hazardous range for several days. The local government even implemented car rationing scheme know as "odd-even" formula to tackle rising air pollution in the city.
Delhi tops the chart of the most polluted city in the world.
Industrial activities and vehicular traffic are significant contributors to air pollution in the city, along with rampant construction. For the past many years, every year ahead of winter the air quality in Delhi became hazardous.
Officials in Delhi blame the stubble burning in neighbouring states of Punjab and Haryana for the increasing pollution.