NEW DELHI: Delhi’s air quality continued to remain in the ‘severe’ category for the second consecutive day on Wednesday with an air quality index (AQI) of 407. Air Quality Early Warning System for Delhi, a system under the Union ministry of earth sciences, said significant improvement in the air quality was likely from December 27. The city is expected to receive rain on December 27 and 28 under the influence of a western disturbance.
Experts said calm wind, low mixing layer height and temperature led to accumulation of pollutants. Though no cold wave was reported in the capital on Wednesday, the minimum temperature was recorded at 4.4 degrees Celsius, three degrees below normal, at Safdarjung, which is the city’s base station. The night temperature was recorded at 4.2 degrees Celsius at Lodhi Road. Low temperature slows down the dispersal of pollutants.
Dipankar Saha, former head of Central Pollution Control Board’s laboratory, said, “The air quality goes from ‘very poor’ to ‘severe’ category when the wind speed reduces close to 2m/s. In these circumstances, the local pollutants cannot disperse and accumulation increases concentration of pollutants. The only solution is to reduce emissions from all possible sources.”
RK Jenamani, senior scientist at India Meteorological Department, said, “The wind was almost calm but it picked up to 5-10 kmph speed during the afternoon. However, relatively stronger winds are expected from December 27.”
After the air quality had deteriorated in November, Commission for Air Quality Management in National Capital Region and Adjoining Areas had imposed some restrictions to control the pollution. However, the major restrictions like closure of thermal power plants, construction ban, entry of trucks into Delhi, closure of schools and educational institutes and closure of industries were recently lifted.
According to the early warning system, the air quality is likely to remain in ‘very poor’ category till December 25 and improve thereafter. “Significant improvement may be seen from December 27 when AQI will reach in poor/moderate category.”