Pollution levels in Delhi deteriorated on Tuesday to the severe category with an air quality index (AQI) of 424 on Tuesday the highest so far this year as the layer of acrid smog persisting over the capital thickened amid calmer winds and raging farm fires in Punjab.
NASA's satellite images showed a dense cluster of red dots denoting farm fires in Punjab and parts of Haryana, and a layer of smoke blanketing huge swathes of the Indo-Gangetic plains -- from east Pakistan to east Uttar Pradesh.
As per the bulletin released by the Central Pollution Control Board (CPCB), the AQI of the national capital stood at 424 at 4pm. However, the AQI of the neighboring states of the Delhi such as Greater Noida (402) and Faridabad (403) also slipped to the ‘severe’ category, while Ghaziabad (381) and Noida (398) remained under the ‘very poor’ category.
Out of the total 35 station, 22 stations in the city recorded the AQI in the ‘Severe’ category including Sonia Vihar (465), Vivek Vihar (446), and Wazirpur (450), Ashok Vihar (450), Bawana (435), Burari (437), DTU (416) , Dwarka-Sector 8 (425), ITO (412), Jahangir Puri (450), Jawahar Lal Nehru stadium (408), and Major Dhyan Chand National Stadium (417. According to the CPCB, the concentration of lung-damaging fine particles known as PM2.5 was above 450 micrograms per cubic metre, around eight times the safe limit of 60 micrograms per cubic metre, in many areas.
PM 2.5 level from 61 to 120 is considered “moderate to poor”, 121 to 250 is “very poor”, 251 to 350 is “severe” and more than 350 is “severe plus”. According to an analysis by the Delhi Pollution Control Committee (DPCC), people in the capital breathe the worst air between November 1 and November 15 when stubble burning peaks. The city records an average PM2.5 concentration of 285 micrograms per cubic metre from November 1 to November 15. An official at the India Meteorological Department (IMD) said a thick layer of smog lowered visibility to 600 metres at the Safdarjung airport and 900 metres at the Palam airport in the morning.
Low wind speed and low temperatures at night are allowing accumulation of pollutants, said Mahesh Palawat, vice president (meteorology and climate change), Skymet Weather.
However, the transport-level wind direction and speed is favourable for transport of smoke from stubble burning. He said humidity may increase and the wind speed may reduce further from November 4 under the influence of a strong Western Disturbance leading to another episode of smog. System of Air Quality and Weather Forecasting And Research (SAFAR), a forecasting agency under Union Ministry of Earth Sciences, said share of farm fires in Delhi PM2.5 pollution stood at 22 per cent on Monday. It was 26 per cent on Sunday, the highest this year so far, and 21 per cent on Saturday.
The Indian Agricultural Research Institute (IARI) reported 1,842 farm fires in Punjab on Tuesday and 2,131 on Monday - the highest so far this season.
Punjab has recorded a total of 17,846 farm fires since September 15, when stubble burning usually begins. Of this, 102,229 were recorded in the last eight days.
Environment Minister Gopal Rai on Tuesday reiterated that Punjab would have seen a large reduction in stubble burnAing had Centre supported state government's “mega plan” to provide cash incentive to farmers for not burning crop residue.