The air quality of Delhi nosedived to ‘severe’ category on Tuesday and may further deteriorate to ‘severe+’ on Wednesday.
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A respite from the extreme air pollution is not likely for the next two days and a “slight improvement” is expected only by Friday, said government-run monitoring agency System of Air Quality and Weather Forecasting and Research (SAFAR).
‘Severe’ air quality can cause respiratory problems in healthy people and has serious health impact on people with lung or heart diseases. People are advised to avoid outdoor physical activities, skip morning walks and close room windows. “Stop any activity if you experience any unusual coughing, chest discomfort, wheezing, breathing difficulty or fatigue and consult a doctor,” read an advisory by SAFAR.
The average level of PM2.5 on Tuesday was six times (366.8 ug/m3) the safe limit (60 ug/m3) in Delhi-NCR at 7 p.m., as per the Central Pollution Control Board.
Causes for spike
The contribution of stubble burning in neighbouring States to Delhi’s pollution was 25% on Tuesday, up from 18% on Monday. The contribution was as high as 44% earlier this season.
The air quality has deteriorated due to low wind speed, cloudy conditions, low mixing height and an increase stubble burning, said authorities.
Mixing height is the height of the atmosphere in which pollutants are spread out. Lesser mixing height leads to higher pollution.
“The sky is likely to be partly cloudy for the next two days under the influence of an approaching western disturbance, but no precipitation is expected,” said SAFAR. Cloudy conditions lead to lesser hours of sunlight, which increases pollution.
“Sunlight heats up the surface and the air near it. Due to this, the air rises, along with water vapour and pollutants, thus decreasing pollution. So, less sunlight can lead to higher pollution,” said Kuldeep Srivastava, head of the regional weather forecasting centre of the India Meteorological Department. The wind speed, which is currently around 2 km/hr, is expected to be over 20 km/hr on Friday and may help in dispersing pollutants.
Air pollution has been linked to multiple diseases. In 2017, 1.24 million people died in India due to air pollution, as per a study funded by the Indian government and the Bill & Melinda Gates Foundation.
