Delhi's air quality likely to worsen as Diwali approaches
The air quality of Delhi and neighbouring areas deteriorated on Tuesday, turning "severe", with a rise in particle pollutants overnight, mostly due to the local sources of pollution.
A Supreme Court-appointed committee has already ordered the pollution control panels of Delhi and neighbouring states to stop all the dust generating construction activities from November 1 to 10, when the pollution is supposed to peak.
At 4 p.m., the Air Quality Index (AQI) of Delhi, which includes 36 regions, was 401 considered "severe". The AQI was 451 at Ghaziabad, 426 at Gurugram, 408 at Noida and 413 on Faridabad, all considered "severe". Greater Noida was the least polluted with near severe AQI at 394, on a scale of 0 to 500.
According to the Central Pollution Control Board (CPCB), the "severe" levels affect healthy people and seriously impact those with existing diseases.
The city was covered in a smoky haze due to a high volume of trapped pollutants that affect visibility and hurt eyes of commuters. Experts warned that episodes of smog will begin in a couple of days.
"It is haze since ozone is at a good level. We cannot call it smog," K.J. Ramesh, head of India Meteorological Department (IMD) told IANS. Haze is the reflection of sunlight from particulate matter (PM). Smog, which is far denser, is a mixture of moisture and PM and allows for limited visibility.
According to the Central Pollution Control Board (CPCB), the air quality is set to deteriorate further from November 1, and the Diwali this year is likely to be more polluted.
"Currently Delhi has trapped pollutants because dispersion is negligible. There is hardly any wind, so the pollutants are from local sources and dust," Mahesh Palawat, director Private Weather forecasting agency Skymet told IANS.
According to Met officials, the local pollutants are largely a combination of meteorological reasons and dust generating from vehicles and renovations of buildings due to festival season.
On Tuesday, almost all places in the NCR saw a sharp rise in the major pollutants -- PM2.5 and PM10 -- particles in the air with diameters less than 2.5mm and 10mm, respectively.
Across 35 active pollution monitored area in Delhi, the average concentration of PM2.5 and PM10 was 263 microgrammes per cubic meters and 472 units by 7 p.m. The same PM2.5 and PM10 concentration across 48 monitored area of National Capital Region (NCR) were 257 units and 457 units.
Air quality is considered "severe" when either AQI is between 401 and 500 or PM2.5 is between 250 and 300 or the PM10 levels are between 430 and 500, according to CPCB.
The safe limit for PM2.5 is 60 units as per national standards and 25 units according to the international standards. For PM10, up to 100 units is safe from national standards and 50 units international standards.
"Both PM2.5 and 10 get into the lungs and cause cardiovascular and respiratory diseases, but PM2.5 is more dangerous because it mixes with bloodstream," Shambhavi Shukla, a researcher with the CSE, told IANS.
She said some international studies have noted that particle pollutants have a direct effect on life expectancy.
(With inputs from agencies.)