Delhi air quality improves slightly, lands in ‘very poor’ category

Vibha Sharma

New Delhi, December 5

A day after the air quality of Delhi-NCR shot up to the “severe” category, the AQI this morning showed a marginal improvement. Though still hazardous, it landed in a slightly better “very poor category” with AQI registering around 363.

An AQI between 201 and 300 is considered “poor”, 301 and 400 “very poor”, and 401 and 500 “severe”. The AQI between 0-50 is considered “good”, 51 and 100 “satisfactory”, 101 and 200 “moderate”.

Notably, air pollution levels and hazardous air quality post-Diwali remained one the major bones of contention and political mudslinging between two key political entities—the BJP and the AAP— in Delhi in the month of October with the saffron party leaders majorly blaming Arvind Kejriwal-led party over mismanagement of ‘parali’—paddy stubble—in Punjab where it is in power.

However, even though there is no ‘parali’ burning now, the air quality on Sunday forced the Commission for Air Quality Management (CAQM) to invoke Stage III of the Graded Response Action Plan (GRAP) with immediate effect, banning construction and demolition activities, particularly stone crushers and mining and associated activities, industrial operations, brick kilns, hot mix plants using non-approved fuels.

The fact is there are many reasons for higher pollutants in the air like C&D, vehicular traffic and topographical and weather conditions and patterns being a few.

There is a close relationship between air pollution and winds and temperatures. According to experts, the concentration of air pollution depends closely on wind parameters like speed, direction and air pressure. Therefore, to study and tackle air pollution of any region, it is also important to check its weather pattern.

Wind speed is inversely proportional to the concentration of pollutants in the air. Therefore, if winds are calm and low, pollutants will not disperse. Cooler air can also trap airborne pollutants longer while warm air carries them higher than the ground level—a reason why weather conditions play a major role in enhancing pollution.

Meanwhile, though the surface winds have started to pick up again in the Delhi region, the AQI is expected to remain in the “very poor” category for the next three days. A gradual drop in the AQI is expected as weather conditions become more favourable.