With level of pollutants like PM10 and PM 2.5 increasing to 265 and 129, the quality of air in Delhi and the National Capital Region plummeted to the poor and very poor category on Tuesday. India Meteorological Department's Delhi wing observed that significant trimming in stubble burning along with the change in wind direction can improve the situation. Also, the key role of local, industrial and construction site pollutants adds to the worsening air condition.
Kuldeep Srivastava, head of IMD's regional weather forecasting centre told ANI, "Three factors are involved for deteriorating air quality. The stubble burning in Punjab and Haryana and the local pollutants generated by industry or construction sites. Winds brought smoke of stubble burning towards Delhi/NCR. Change in wind direction and significant reduction of stubble burning will help in improving air quality."
The Delhi/NCR region is experiencing northwesterly winds over the last few days. "Since the last two days, wind speed has decreased incapacitating pollutants to disperse. Wind direction has changed to easterly today. Accumulation of pollutants has deteriorated the air condition," observed Mr Srivastava.
Amid increasing levels of air pollution in the national capital region, close to 700 cases of stubble burning were reported from Punjab and Haryana between September 21-29. Over a period of nine days, Active Fire Events (AFE) registered in Punjab and Haryana this year are 579 and 120 against a much-lower number of 208 and 27 last year.
The Environment Pollution (Prevention & Control) Authority (EPCA) issued a letter to Chief Secretaries of Delhi, Uttar Pradesh, Haryana, and Rajasthan last week on the implementation of the Graded Response Action Plan (GRAP) in an endeavour to keep air pollution at its lowest.
"The temperature will vary between 20/21 degrees in Delhi/NCR for a few days before decreasing further. The upcoming decrease in temperature will lead to unfavourable air quality. In the coming days, conditions are not that favourable," Mr Srivastava said.
Winter mostly depends on western disturbances. When western disturbances approach northwest India, winter begins. In the coming 10 days, there will be no active western disturbance which will affect northwest India.
An AQI between 0 and 50 is considered ''good'', 51 and 100 ''satisfactory'', 101 and 200 ''moderate'', 201 and 300 ''poor'', 301 and 400 ''very poor'', and 401 and 500 ''severe''.