CAQM lifts GRAP IV as AQI improves

As Delhi’s air quality improved to ‘poor’ at 271 on Wednesday on the back of stronger winds, though the conditions are forecast to worsen again, the Commission for Air Quality Management (CAQM) revoked the strictest restrictions under Graded Response Action Plan-1V. These curbs were imposed on December 13. However, restrictions under GRAP-3,2 and 1 will remain in force, the CAQM said.

Delhi’s 24-hour average air quality index (AQI) stood at 271, in the ‘poor’ category, on Wednesday, a sharp improvement from the ‘severe’ AQI of 412 recorded at 4 pm on Tuesday, according to the Central Pollution Control Board (CPCB) data.

The last time the city’s air quality was recorded in the poor category was on December 10, after which it remained in the ‘very poor’ and ‘severe’ zones for several days before improving again on Wednesday. Favourable meteorological conditions, particularly surface wind speeds of 15–25 kmph during the day, helped improve air quality. The predominant surface wind was from the northwest, with speeds reaching up to 20 kmph during the afternoon hours.

However, the wind speeds are expected to decrease to below 10 kmph from the west direction during the evening and night, according to the Air Quality Early Warning System.

Out of the 40 functional air quality monitoring stations in the city, four recorded ‘moderate’ AQI levels below 200 -- Lodhi Road, IIT Delhi, IGI Airport and Aya Nagar -- while 33 were in the poor category.

Only two stations -- Nehru Nagar and Dwarka -- recorded ‘very poor’ AQI above 300, according to the CPCB’s SAMEER app.

The CPCB classifies an AQI between 0 and 50 as ‘good’, 51 and 100 as ‘satisfactory’, 101 and 200 as ‘moderate’, 201 and 300 as ‘poor’, 301 and 400 as ‘very poor’ and 401 and 500 as ‘severe’.

Data from the Decision Support System (DSS) for Air Quality Management showed that vehicular emissions were the largest contributor to Delhi’s pollution load on Wednesday, accounting for 17.5 per cent. This was followed by industries in Delhi and adjoining areas (8.6 per cent), construction activities (2.4 per cent) and waste burning (1.3 per cent).

Among the NCR districts, Jhajjar in Haryana contributed the highest share to pollution at 12 per cent, followed by Sonipat (6.5 per cent) and Rohtak (5.4 per cent) in Haryana and Ghaziabad (2.7 per cent) in Uttar Pradesh, the data showed.

However, the Air Quality Early Warning System said that Delhi’s air quality is likely to slip back into the ‘very poor’ zone over the next six days. On the weather front, Delhi on Wednesday recorded a maximum temperature of 22.7 degrees Celsius, two notches above normal, and a minimum of 10.2 degrees Celsius, 2.7 degrees above normal, the India Meteorological Department (IMD) said. The relative humidity stood at 100 per cent at 8.30 am and 78 per cent at 5.30 pm.

The IMD has forecast a minimum temperature of 6 degrees Celsius and a maximum of 22 degrees Celsius for Christmas Day on Thursday, with mainly clear sky after shallow to moderate fog at many places during morning hours.

The predominant surface winds are likely to be from the west at up to 10 kmph in the morning, increasing to around 12 kmph from the northwest in the afternoon before weakening to below 5 kmph from the north during the evening and night, according to the Air Quality Early Warning System.