An AQI between 0-50 is considered good, 51-100 is satisfactory, 101-200 moderate, 201-300 poor, 301-400 very poor and 401-500 is marked as severe/hazardous.
The air quality in the national capital on Thursday morning plunged to "severe levels" for the second consecutive day, said System of Air Quality and Weather Forecasting and Research (SAFAR).
SAFAR has advised 'Sensitive Groups' to reduce prolonged or heavy exertion. People are advised to take more breaks and do less intense activities.
According to SAFAR, the rise in air pollution is because of the prevalence of calm surface winds and decrease in ventilation coefficient which creates a conducive environment for pollutant accumulation.
The national capital will witness strong surface winds during the day time today and the temperature would be oscillating between 9 degrees Celsius to 24 degrees Celsius, predicted India Meteorological Department (IMD).
The national capital region has been reeling under harmful levels of air pollution ever since Diwali, majorly owing to stubble burning in the neighbouring states of Haryana, Punjab and Uttar Pradesh.
The PM 10 levels were slightly better at Lodhi Road, docking in at 135 which falls in the 'moderate' category while the PM 2.5 remained 'poor' at 235.
Today, the overall air quality of Delhi was recorded at 218, with PM 10 at 155 and PM 2.5 at 67. People of the city expressed happiness over the improved air quality. "The pollution levels have definitely come down. The air is much cleaner today," said a resident of the city.
This was the third edition of the odd-even restrictions, a flagship scheme of the AAP government, on private vehicles in Delhi.
Air quality condition is likely to marginally improve by tomorrow (Friday), but a reasonable improvement to the 'very poor' is expected only by November 16 (Saturday).