Delhi air quality index: Pollution in Delhi, National Capital Region may worsen over the next week

Air quality in Delhi is expected to remain "poor" for a fourth straight day today, with the national capital likely to record an Air Quality Index of 256, up from 222 on Saturday and 208 on Friday. The AQI is likely to worsen to "very poor" by the third week of October, according to the centre-run System of Air Quality and Weather Forecasting and Research (SAFAR). Certain neighbourhoods in Delhi, such as Anand Vihar and Wazirpur, have already recorded AQIs of more 300, placing them in the "very poor" category.

The deterioration of air quality has been linked to stubble burning in the neighbouring states of Punjab and Haryana. Stubble burning has also contributed to an increase in PM2.5 levels - atmospheric particulate matter with a diameter less than 2.5 micrometres - with the concentration of the pollutant expected to rise to 6 per cent by Tuesday.

"The fire counts in Punjab and Haryana have increased significantly over the last two days. The wind direction in Delhi is westerly which is unfavourable thereby carrying the smoke from the stubble burning towards Delhi," LS Kurinji, a research analyst with the Council on Energy, Environment and Water (CEEW), was quoted by news agency IANS.

"Delhi will probably encounter poor air quality in the coming days due to the prevailing wind direction and the stubble burning," she added.

Delhi air quality has been declared "poor" for the first time in three months. It had remained "satisfactory" between July and September, aided by the monsoon and favourable wind conditions.

The National Green Tribunal had banned crop residue burning in Haryana

In 2015, the National Green Tribunal banned crop residue burning in Rajasthan, Uttar Pradesh, Haryana and Punjab. The ban seemed to have little effect - last year, NASA released images of farm fires from Punjab and Haryana, where more than 120 cases have been reported this year, showing crop residue burning as the cause of air pollution.

Air quality levels are likely to become a political battleground between the ruling Aam Aadmi Party (AAP) and the opposition BJP ahead of Assembly polls expected in 2020.

Addressing a press conference in Delhi last week, Environment Minister Prakash Javadekar said the Central Pollution Control Board (CPCB) had deployed 46 teams to track pollution levels and take appropriate action.

Delhi Chief Minister Arvind Kejriwal, who addressed a climate change summit in Denmark via video conference on Friday, after being denied permission to attend by the centre, raised the issue during his talk and said his AAP government had reduced air pollution levels by 25 per cent over the past three years, thanks to initiatives like the "odd-even scheme" that will come into effect between November 4 and November 15.

With input from PTI, IANS