Saturday saw a dip in pollution levels in the city that can partially be attributed to weather conditions at this time.
Levels of fine particulate matter (PM2.5) fell during the day on Saturday, owing to weather conditions conducive to dispersion of pollutants. As per the SAFAR air quality index, the level of PM2.5 decreased from 212 micrograms per cubic metre at 1 a.m. to 187 as of 6 p.m.
The National Air Quality Index also reflected slightly less pollution on Saturday, with three monitoring stations showing “severe” warnings.
Last week, four or five stations had severe pollution.
“Wind is the single major factor that affects local pollution, irrespective of the changing of sources. Stronger winds sweep away many pollutants while light winds or no winds hardly remove it. There were 3 to 8 kmph winds on January 1, during 11 a.m. and 5 p.m. while on January 2, during the same period the wind speed was between 8 to 16 kmph,” said Dr. R.K. Jenamani, Director-in-Charge of the met unit at Indira Gandhi International Airport.
“Thanks to the impact of the wind, even the smog cover over the airport, which in terms of visibility at IGIA was between 600 to 1,200 metres reported for 8 a.m. to 5 p.m. on January 1, it had improved to 1,000 metres to 1,800 metres on Saturday during the same period,” he said. “Moisture in air at lower levels is the second important parameter, which if it holds pollutants for longer period can create smog in absence of wind and it does not disperse easily as particle grows with getting hydration from more vapour available in air,” he said.
“What did not favour more smog on Saturday was the fact that humidity has been less by 5 to 10 per cent on Saturday compared to Friday,” he said.
Levels of fine particulate matter (PM2.5) fell due
to unusually
strong winds
