A fog-like blanket that engulfed the national capital on Thursday morning was actually smog, a deadly cocktail of toxic car exhaust fumes and smoke from the ecologically-damaging practice of burning crop stubble in neighbouring states.
Given the weather conditions, the smog is likely to linger for some time — create a sunscreen, vitiate the air even further and bring misery to people with respiratory ailments.
“The term fog is used when visibility is less than 1km and the relative humidity exceeds 75%. Delhi generally experiences fog at the end of December. However, lack of rain, a drop in temperature and harmful gases and pollutants create smog. Absence of moisture in the air along with high levels of pollution caused this,” a senior Met official said.
The city woke up to a cold morning with the minimum temperature settling at 11.5 degrees Celsius, a notch below normal for this time of the year, and most people mistook the smog for fog.
The weather official said smog will form whenever relative humidity drops due to the high amount of vehicular pollution in the Capital as well as the burning of post-harvest stalks of paddy and other cereal plants in UP, Haryana and Punjab.
The two conditions combined to worsen the air quality of Delhi, which tops the 2014 WHO list of world’s top 20 polluted cities. People here breathe airborne particulate matter six times more than what is considered safe.
No doubt, people with asthma and other respiratory diseases were having a hard time of late. “For the past week, I am having trouble breathing. My chest aches and I have to take the inhaler for comfort. My dust allergy has worsened. I start sneezing as soon as I step outside. And then, the wheezing starts. I have been taking the inhaler twice every day,” said Usha Das, a 26-year-old resident of Mayur Vihar.
The smog has put the young and elderly severely under the weather.
“Children and elderly are more vulnerable and should be more careful. Severe breathlessness caused by the suspended particles can result in respiratory failure. The probability of a heart attack increases among the elderly. Those with asthma or heart disease should be kept under medical supervision,” said Dr TK Joshi, director of occupational and environmental programme, Maulana Azad Medical College.
Readings of the System of Air quality and Weather Forecasting and Research (SAFAR), which is jointly run by the Indian Institute of Tropical Meteorology and India Meteorological Department, reveal the poor air quality on Thursday. In Pitampura, the index read “severe” while Gurgaon’s was “very poor”. The average PM10 reading was 223.8 µgm-3 while PM2.5 was recorded at 131µgm-3.
The weather office predicted winter to arrive on November 23, when the mercury is likely to dip below 9 degrees Celsius. “Western disturbances are weak because of which there has not been much of a drop in temperature even in November. However, after about four days, this is going to change,” an official said.