The national capital recorded its best air quality in over two months on Thursday after rains washed away pollutants, even as authorities warned that the respite would not last long due to unfavourable weather conditions.
The city's air quality index (AQI) dropped to 193, which falls in the 'moderate' category. The last time Delhi's air quality fell in moderate category was in October beginning.
Delhi's air quality has been in the severe category for the last three days with an AQI of over 400, according Central Pollution Control Board (CPCB) data.
The respite comes after overnight rainfall, which along with moderate winds managed to wash away the pollutants significantly, the Centre-run System of Air Quality and Weather Forecasting (SAFAR) said.
Fourteen areas in Delhi recorded 'poor' air quality and in 19 areas it was 'moderate'.
The overall PM2.5 level (fine particulate matter in the air with a diameter of less than 2.5 micrometre) was recorded at 93 and the PM10 level at 160, it said. The AQI on Monday was 412, on Tuesday 415 and 413 on Wednesday morning.
An AQI between 100 to 200 comes under moderate category, 201 and 300 is considered 'poor', 301 and 400 'very poor' and 401 and 500 'severe'.
Neighbouring Ghaziabad and Faridabad recorded 'poor' air quality, while Gurgaon and Noida recorded 'moderate' air quality, the CPCB data showed.
"However, respite is expected not to last longer as humidity is very high and temperature is likely to cool. Both factors are unfavourable and may push AQI to 'very poor' level by tomorrow (Friday)," the SAFAR said.
According to the Indian Institute of Tropical Meteorology, the maximum ventilation index is likely to be 3,500 sqm/second on Thursday and 7,000 sqm/second on Friday.
A ventilation index lower than 6,000 sqm/second with average wind speed less than 10 kmph are unfavourable for dispersion of pollutants.