New Delhi, Nov 5 : The share of stubble burning in Delhi's air pollution rose to 42 per cent on Thursday, the maximum so far this season, as city's residents woke up to air quality in severe category, according to a central government's air quality monitoring agency. On Wednesday, stubble burning had contributed only five per cent to Delhi's pollution, 10 per cent on Tuesday and 16 percent on Monday and 40 per cent a day before. Last year, the farm fire contribution to Delhi's pollution had peaked to 44 per cent on November 1. Capital city's air quality index stood at 471 micrograms per cubic meter at noon, in severe category. According to the Central Pollution Control Board, all the 35 pollution monitoring station in Delhi showed severe air quality index reading. Vivek Vihar in East Delhi has the most noxious air at 495. Delhi's neighbouring regions -- Ghaziabad, Faridabad, Noida and Greater Noida are logging severe quality of air. Ghaziabad and Greater Noida's air quality remained by far worse, with air quality of 490 and 476 micrograms per cubic meter, respectively, almost touching the hazardous category. According to Head of India Meteorological Department's Regional Forecasting Centre, Kuldeep Srivastava, "There is a layer of pollutant in the atmosphere from the smoke emanating from the stubble burning and local sources. There will be no respite for the next two-three days (till Sunday)." Severe air quality causes respiratory issues in healthy people, and serious health issues in people with lung or heart disease. People may also experience difficulty doing light physical activity. According to Ministry of Earth Science's System of Air Quality and Weather Forecasting and Research, Delhi, "SAFAR synergized stubble fire counts over Punjab, Haryana, UP, Uttarakhand, and neighbouring areas increased significantly and stood at 4,135 on Wednesday, the highest of the season." The air quality forecasting agency also said that the boundary layer wind direction is favourable for direct fire-related transport and that the "stubble burning share in PM2.5 in Delhi's air is estimated as 42 per cent for Thursday." "Current sudden deterioration is attributed primarily due to very low boundary layer height and sudden increased injection of fire-related pollutants due to favourable transport winds. "Better Dispersion condition and not so low day time boundary layer height is forecasted for the next two days likely to improve AQI unless more than estimated fire-related emission take place." /IANS