Noida, Ghaziabad 'most polluted' cities with AQI in 'severe' category

The air quality index in Delhi and NCR fell to 'severe' category on the second day of the new year as weather turned unfavourable. Ghaziabad and Noida turned to be the most polluted cities on the new year, occupying first and second spots as the AQI fell in the 'severe' category.

The cold, dense fog and low wind speed kept pollutants, mostly from local source, trapped in the air, said weather analysts. They expect ventilation to improve slightly over the next 24 hours, but it may take until January 3 to pull the two cities out of the 'severe' category.

Meanwhile the air quality index of Gurugram fell under 'very poor' category. Presence of particulate matters, PM 2.5 and PM 10, remained high in Delhi's five neighbourhood - Ghaziabad, Noida, Greater Noida, Faridabad and Gurugram, according to the Central Pollution Control Board (CPCB).

The average 24-hour AQI at 4 pm on Saturday was 462 in Ghaziabad, 450 in Greater Noida, 448 in Noida, 415 in Faridabad and 336 in Gurgaon, according to CPCB's Sameer app.

According to the index, an AQI between zero and 50 is considered 'good', 51 and 100 'satisfactory', 101 and 200 'moderate', 201 and 300 'poor', 301 and 400 'very poor', and 401 and 500 'severe'.

The CPCB states that an AQI in the 'severe' category affects healthy people and seriously impacts those with existing diseases while 'very poor' may lead to respiratory illness on prolonged exposure.

The AQI for each city is based on the average value of all stations there. Noida, Faridabad, Ghaziabad have four stations each, while Gurgaon has three and Greater Noida two, according to the app.

According to the System of air quality and weather forecasting and research (SAFAR), the AQI is set to improve to the very Poor category by Saturday January 2 and further improve to ‘poor’ category by Sunday January 3.