Delhi's air quality 'very poor' for fourth straight day; AQI over 400

Delhi's air quality was recorded in the 'very poor' category for the fourth consecutive day on Thursday, according to Central Pollution Control Board data.

The air quality index (AQI) in Anand Vihar (428) and Ashok Vihar (405) was recorded in the 'severe' category at 6:30 pm, the CPCB data showed.

The AQI in Wazirpur, Bawana, Jahangirpuri and Mundka was in the 'very poor' category.

The neighbouring cities of Ghaziabad (373), Noida (354), Greater Noida (368), Gurugram (362) and Faridabad (315) reported 'very poor' air quality.

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 air quality in the national capital started deteriorating from October 24 with the AQI slipping to the 'very poor' category from 'poor'.

Pollution levels crept up on the night of October 23 amid a drop in temperature and wind speed and due to people bursting firecrackers and a rise in the number of farm fires.

On October 19, the sub-committee of the Commission for Air Quality Management (CAQM) had implemented Stage II of the Graded Response Action Plan (GRAP) a set of anti-air pollution measures followed in Delhi and its vicinity according to the severity of the situation in the capital.

GRAP's Stage II includes banning the use of coal and firewood in hotels, restaurants and open eateries. The use of diesel generators, except for essential services, is also banned.

GRAP is classified under four stages depending on the air quality in Delhi. Stage I in a case of 'poor' air quality (AQI 201-300), Stage II for 'very poor' air quality, Stage III for 'severe' air quality (AQI 401-450), and Stage IV for 'severe plus' air quality (AQI>450).

If the situation turns 'severe' (Stage III), authorities will enforce a ban on construction and demolition activities in NCR, except for essential projects (such as railways, metros, airports, ISBTs and national security/defence-related projects of national importance).

Brick kilns, hot mix plants and stone crushers not operating on clean fuels, and mining and associated activities in NCR will also be banned under Stage III.

The state governments in Delhi-NCR may also impose restrictions on BS-III petrol and BS-IV diesel light motor vehicles (four-wheelers) under Stage III.

The measures in the 'severe plus' category or Stage IV include a ban on the entry of trucks into Delhi and on plying of Delhi-registered diesel-run medium goods vehicles and heavy goods vehicles in the city, except those carrying essential commodities.

The use of four-wheeler diesel light motor vehicles, except for BS-VI vehicles and vehicles engaged in essential services, will also be banned in Delhi and the bordering districts of NCR.

Stage IV will also entail a ban on industries running on dirty fuels and on construction and demolition activities in linear public projects such as highways, roads, flyovers, over bridges, power transmission and pipelines.