Cold wave grips Delhi-NCR, air quality falls to poor in Delhi

Air quality in Delhi remained 'poor' on Tuesday (January 21) with air quality index (AQI) crossing 250 in most parts of the capital. The overall AQI docked at 282 with the air quality at Chandni Chowk and Ayanagar recorded at 326 and 217, said System of Air Quality and Weather Forecasting And Research (SAFAR). The air quality in Noida and Gurugram was recorded at 323 (very poor category) and Gurugram at 270 (poor).

The minimum temperature recorded at Safdarjung was 10.6 degree celsius and it was 9.6 degree celsius near Palam at 5:30 am. The visibility at Safdarjung was 500 meters, while it was just 250 meters at Palam.

An AQI between 0-50 is considered `good`, 51-100 `satisfactory`, 101-200 `moderate`, 201-300 `poor`, 301-400 `very poor` and 401-500 is marked as `severe`. An AQI above 500 falls in the `severe plus` category.

During winter each year, most of northern India suffers from a spike in toxicity in the air due to the change in weather patterns and crop residue burning in the neighbouring states of Haryana, Punjab and Uttar Pradesh.