New Delhi: The air quality in national capital dropped towards ‘very poor category’ on Wednesday. In some areas, the Air Quality Index (AQI) was recorded to be a hazardous level. An AQI between 0 and 50 is considered “good”, 51 and 100 “satisfactory”, 101 and 200 “moderate”, 201 and 300 “poor”, 301 and 400 “very poor” and that between 401 and 500 is categorised as “severe”.

During wee hours on Wednesday, the AQI was recorded to be at 407 at Anand Vihar whereas, it was 280 at Mandir Marg. Meanwhile on Tuesday, the overall Air Quality Index (AQI) of Delhi was recorded at 293, just eight points below the ‘very poor’ category. The PM10 level (presence of particles with diameter less than 10 micrometres) in Delhi stood at 274 and the PM2.5 level was recorded at 119. Both PM10 and PM2.5 are in poor category, according to Central Pollution Control Board’s data.

Several factors like vehicular pollution, construction activities and meteorological factors like wind speed are believed to be responsible for continuing pollution in the city.

On Monday, an emergency plan to combat air pollution came into force in Delhi-NCR. The Graded Response Action Plan (GRAP), which has come into effect for the second year, ensures stringent actions are taken based on the air quality.

Under the plan, measures like mechanised sweeping of roads, ban on garbage burning, pollution control measures at brick kilns and deployment of police to ensure smooth passage of traffic at vulnerable areas are in force in Delhi-National Capital Region (NCR) as the air quality lies in the poor category.

Furthermore, a ban on the use of gensets has also been imposed in the city. However, they are being allowed to operate in parts of the NCR due to power issues.

The GRAP, notified by the Ministry of Environment, Forest and Climate Change in 2012, prescribes a set of measures to curb air pollution based on the Central Pollution Control Board’s (CPCB) daily Air Quality Index (AQI).

The emergency plan gets implemented if “very poor” or “severe” air pollution levels are recorded for 48 hours but given the extent of winter pollution witnessed by the national capital, the plan has been implemented as the air quality slipped to the “poor” category.

Air pollution in Delhi and nearby states increases particularly due to burning of paddy straw during October and November and wheat straw during April in Punjab and Haryana. Recently, NASA had released images showing rampant stubble burning activity in the two states. On its official website, it had stated that burning of crop residue in Punjab and Haryana has increased significantly over the past 10 days in and near Amritsar, Ambala, Karnal, Sirsa and Hisar.