Air quality improves marginally in the national capital

The air quality in Delhi improved slightly on Tuesday but continued to be in the 'poor category', according to the AQI index of the Central Pollution Control Board.

This could be, perhaps, due to the easterlies that have reduced the impact of the northwesterlies which have been bringing the biomass from stubble burning in the states of Haryana and Punjab to Delhi.

The AQI recorded on Tuesday was 206 as against Monday's 249.

On Tuesday evening, the Air Quality Index recorded by the Siri Fort monitoring centre of the Central Pollution Control Board was 305 (very poor), the highest in the city.

Kuldeep Srivastava, head of India Meteorological Department's Regional Weather Forecasting Centre (RWMC), said the easterlies could help in checking the biomass movement from Punjab and Haryana but it will not have any effect in dealing with external pollutants.

However, the air quality is likely to improve further in the last week of October due to a western disturbance, SAFAR (System of Air Quality and Weather Forecasting And Research) said. This also coincides with Diwali.

"The repeated western disturbances are expected in the last week of October, which is likely to positively influence Delhi's air quality. A fresh WD is expected to have an impact by October 23 and one more WD is expected by the end of this month," it said.

The calm anticyclonic condition is expected to recoup only by the first week of November and associated sinking motion will make the atmosphere very stable with calm surface winds, it added.

"Both will lead to stagnant weather conditions, which favour rapid fine particulate matter formation and accumulation of pollutants. The crisis deepens if it is encountered with any additional internal or external emissions (stubble burning) sources," it added.

"In a landlocked city like Delhi, it may lead to rapid accumulation and may trigger high pollution events. If local emissions are controlled, we may avoid air quality crises," it added.

Stubble burning in Punjab and Haryana has been a vital factor in spiking the AQI in Delhi. This year, Punjab recorded a 25 per cent increase in stubble burning incidents as compared to 2018, which the state government attributed to early harvesting of paddy crop this year.

The number of farm fires in Haryana, however, has decreased by 10 per cent as compared to last year, despite the "moderate implementation of the ban on stubble burning due to elections", according to officials. Till October 20, Punjab recorded 2,482 cases of stubble burning against 1,980 last year, an increase of around 25 per cent.