The air quality in the national Capital remained in the 'very poor' category on Monday after Sunday's brief spell of rain brought marginal relief from high levels of pollution. The overall Air Quality Index (AQI) as recorded by the Central Pollution Control Board (CPCB) was 333 at 4 pm. On Sunday, the AQI settled at 347, with the city recording its lowest pollution level of the year.

The light showers coupled with sufficient wind speed on Sunday washed away pollutants, helping the city breathe better. According to the authorities, the moderate surface wind speed will aid in cleansing the air of pollutants and make the air breathable during the daytime.

The System of Air Quality and Weather Forecasting And Research (SAFAR), however, has warned that the respite may be shortlived and unlikely to last beyond Tuesday. High levels of humidity and plummeting mercury will trap pollutants present in the air, creating smog like situation. The authorities have also said that the AQI will again rise but is likely to remain in the 'very poor' category. The overall PM2.5 (fine particulate matter in the air with a diameter of less than 2.5 micrometer) level was recorded at 172 which falls in the 'very poor' category while the PM10 (fine particulate matter in the air with a diameter of fewer than 10 micrometres) level was recorded at 263, which is under 'poor' category, according to SAFAR.

Around 22 places in Delhi recorded 'very poor' air quality, while it was 'poor' in two areas. Ghaziabad, Faridabad, Gurgaon and Noida in the National Capital Region recorded 'very poor' air quality, it said.

An AQI between 100 and 200 comes under 'moderate' category, 201 and 300 is considered 'poor', 301 and 400 is 'very poor' and 401 and 500 are considered 'severe'.