Delhi's pollution levels worsen even further as AQI soars above 400

As the national capital's temperatures continue to drop, Delhi's air quality worsened on Dec 18 and approached the "severe plus" category, according to data supplied by the Central Pollution Control Board.

With an air quality index (AQI) value of 445, Delhi remained above 400 for the second consecutive day, making it the nation's most polluted metropolis.

The next highest AQI was 400 in nearby Gurugram, followed by 359 in Ghaziabad and Noida.

Around 67 cities nationwide recorded AQI readings above 200, up from 38 a week ago and 32 on Dec 2.

AQI levels below 100 were reported in less than one-fourth of the 252 cities that submitted data on Dec 18.

At 26.6%, the proportion of cities with AQI readings of 200 also hit its highest point in almost a month.

The situation was the same in the metros. Kolkata likewise had an AQI of about 200, while Mumbai's was at its lowest in 24 days at 199.Hyderabad's AQI was 111, and Chennai's was 120. With an AQI of 92, Bengaluru was the cleanest metropolis. The AQIs of Tirunelveli in Tamil Nadu and Aizwal, the capital of Mizoram, were either the same as or lower than London's, at 25 and 26, respectively.

Depending on the severity of the problem, the air quality is categorized into four stages: "poor" (AQI 201-300) in Stage I; "very poor" (AQI 301-400) in Stage II; "severe" (AQI 401-450) in Stage III; and "severe plus" (AQI > 450) in Stage IV.

As part of the winter air pollution management measures, the Central Air Quality Panel for Delhi-NCR imposed Stage IV limitations under the Graded Response Action Plan (GRAP) on Dec 16.

This included a complete restriction on construction activity, spurred by the region's deteriorating air quality, which had fallen into the 'severe' category due to unfavorable weather conditions.

Roads, flyovers, electricity transmission lines, pipelines, communications infrastructure, and other linear public projects are now included in the Stage III prohibition on construction and demolition (C&D) operations.

For classes VI to IX and XI, schools in Delhi and the National Capital Region (NCR) districts of Gurugram, Faridabad, Ghaziabad, and Gautam Buddh Nagar must implement hybrid learning, providing both online and offline choices.

Students and their parents make the decision to take classes online. Depending on viability, other NCR areas are urged to do the same.

In the NCR, 50% of public, municipal, and private workplaces must be located on-site; the remaining employees must work from home.