Delhi was ranked the most polluted city in India in October, with an average PM2.5 concentration of 111 micrograms per cubic metre. The Centre for Research on Energy and Clean Air (CREA) in its monthly report on air quality revealed the national capital was the most polluted city in October in India and all the top 10 polluted cities in India in October were located in the National Capital Region (NCR).

“ Delhi's October average was 2.5 times higher than September's average of 43 micrograms per cubic metre. Delhi recorded 9 days in the ‘Good’ category, 5 days in the ‘Satisfactory’ category, 8 days in the ‘Moderate’ category, 4 days in the ‘Poor’ (91-120 µg/m³) category and 14 days in the ‘Very Poor’ (121-250 µg/m³) category.  October average is 2.5 times higher than September’s average of 43 µg/m³, when there were 9 days in the ‘Good’ category, 16 days in the ‘Satisfactory’ category, 4 days in the ‘Moderate’ category, and 1 day in the ‘Very Poor (121-250)’ category,” the report said

“Although the average contribution from stubble burning to PM2.5 levels in Delhi was less than 10% in October, the increased PM2.5 concentration indicates contributions from year-round sources,” it added.

The other most polluted NCR cities are Ghaziabad (110 micrograms per cubic metre), Muzaffarnagar (103), Hapur (98), Noida (93), Meerut (90), Charkhi Dadri (86), Greater Noida (86), Gurugram (83), and Bahadurgarh (83).

Meanwhile, Toxic smog hung over the capital city on Tuesday and more stations recorded ‘severe’ air quality even though the overall Air Quality Index of the capital remained in the upper levels of the ‘very poor’ zone for the seventh straight day. The smog that had formed in the morning persisted through the day due to calm wind and mist conditions, due to this pollution kept soaring as the day passed. PM2.5 concentration in Delhi was found 41.4 times the WHO annual air quality guideline value at noon, according to Swiss based IQ Air app.

The city’s average AQI was 373 at 4 pm on Tuesday. This figure was marginally better as compared to the 24-hour average recorded at 4 pm on Monday, when the AQI stood at 381. During the morning, air pollution in many areas in Delhi remained in the “severe” category for the third consecutive day on Tuesday, with the average AQI in Anand Vihar reaching 448 (PM10). Out of the 38 AQI monitoring stations in different parts of the national capital, 13 were in ‘severe’ air quality zones. These included NSIT Dwarka, Nehru Nagar, Moti Marg, Anand Vihar, Ashok Vihar, Dwarka, Sonia Vihar, Vivek Vihar, Punjabi Bagh, Mundka, Wazirpur, Rohini, and Jahangirpuri.

The air quality index is expected to deteriorate in the coming day as experts attributed that AQI is anticipated to remain in the “very poor” or “severe” category as the winds are becoming calm without any new western disturbance.

At present, the major contributors to PM2.5 pollution are local and regional sources.  The tremendous increase in air pollution has been attributed to high volumes of vehicles on roads, construction works, dust, stubble burning and calm winds. The transport sector is the most significant contributor at 10.778 percent, as per the Decision Support System data by the Indian Institute of Tropical Meteorology (IITM). While the residential sector contribution is 2.854 percent, industries contributed (2.67 percent), construction 1. 47percent, energy sector 1.395 percent, waste burning 1.048 percent, and road dust 0.86 percent.

The Delhi government has identified 13 hotspots of air pollution are at Narela, Bawana, Mundka, Wazirpur, Rohini, R K Puram, Okhla, Jahangirpuri, Anand Vihar (including Mandoli), Punjabi Bagh, Mayapuri, Dwarka and Ashok Vihar.

According to early warning system, mainly smog condition with predominant surface wind from variable directions with wind speed reaching 04–06 kmph prevailed during daytime and calm winds during night. “The wind was variable direction in Delhi and NCR with speed of 4-08 kmph, cauing smog/swallow fog in the morning. Predicted maximum mixing depth was estimated 1750 m. The ventilation index lower than 6000 m2/s with average wind speed less than 10 kmph is unfavourable for dispersion of pollutants. Meteorological conditions are likely to be extremely unfavourable for dispersion of pollutants,” it said.

Residents have been advised not to undertake any kind of physical activity outdoors to avoid the risk of inhaling toxic fumes that can lead to respiratory illness in the long term. Air quality worsens when there is an increase in the presence of toxic particulate matter (PM) 2.5 and 10

Environment Minister Gopal Rai said on Tuesday announced to launch a compaign to discourage open burning of waste will begin from Wednesday in view of the rising air pollution. Addressing a press conference, Rai said 588 teams from different civic agencies, including the Municipal Corporation of Delhi (MCD), will be deployed on field to report open burning incidents across the city. "Pollution level in Delhi has reached 400, next ten days are going to be crucial. I held a meeting with 33 departments to take stock of the situation. All departments have been instructed to stay on alert mode," Rai said.