Dust pollution still high in Delhi, could subside with rain on Monday
A dust storm in Oman has pushed up levels of atmospheric dust in Delhi since Thursday.delhi Updated: Aug 05, 2018 12:20 IST
Delhi continued to reel under high dust pollution for the third consecutive day, even as experts said that it could abate on Monday as rain is expected next week.
A dust storm in Oman has pushed up levels of atmospheric dust in Delhi since Thursday. The level of PM10 (particulate matter measuring less than 10 microns), which comprises mostly coarse atmospheric dust, shot up 2.7 times and 2.6 times above the safe standard of 100ug/m3 on Thursday and Friday, respectively. On Saturday, it remained almost 2.6 times above the safe limit.
“The PM10 level started spiking from Thursday. While on Thursday, around 8pm, the level was 277ug/m3, on Friday, it stood at 261ug/m3. On Saturday, the PM10 level, around 8pm, was 264ug/m3. Around a week ago, on July 28, the level was 60.9ug/m3,” P Gargava, member secretary of the Central Pollution Control Board (CPCB), said.
The value of air quality index on Saturday was 216. On Thursday and Friday, it was 235 and 213, respectively. An AQI value between 201 and 301 on a scale of 0-500 is considered to be ‘poor’. In the winter, when pollution levels are at their peak, the AQI touches 500.
The dust storm in Oman started around July 27 and continued for the next four days till July 31. The dust then entered the Arabian Sea over which it lingered for a few days before reaching northwest India and Delhi-NCR. Usually, it takes around two or three days for the dust to reach Delhi from Oman, depending on wind speed and other weather parameters.
“As it was mostly atmospheric dust, the level of ultra-fine particles PM2.5, which is a product of combustion of fossil fuels, didn’t shoot up,” a CPCB official said.
The level of PM2.5 on Saturday 8 pm was around 71ug/m3, which was just few notches above the safe limit of 60ug/m3.
“Atmospheric dust is a natural thing. But it becomes more harmful and toxic when it passes over cities and towns. A variety of minute toxic pollutants such as volatile organic compounds and polycyclic aromatic hydrocarbons, which are emitted by industries, vehicles and power plants, linger in the air. These minute and toxic pollutants cling on to coarser and larger dust particles turning them toxic,” Anumita Roy Chowdhury, executive director (research and advocacy) at Centre for Science and Environment, said.
The dust is expected to abate on Monday as the weatherman has forecast rain. While one western disturbance is approaching the city, a cyclonic circulation is also developing over Delhi and NCR. The monsoon trough is also located near Delhi, India Meteorological Department officials said.
This is, however, not the first time that dust pollution levels in Delhi were pushed up by dust storms in west Asian countries.
In November 2017, when the national capital was reeling under severe pollution, a dust storm in Iraq, Kuwait and Saudi Arabia had contributed to nearly 40% of the dust in Delhi.
In mid-June this year, dust from Rajasthan and beyond the western borders had pushed up PM10 level by at least eight times the safe limit, forcing the government to suspend construction activities.
Minute air-borne salt particles originating from the salt pans in Afghanistan also push up pollution in Delhi, mostly during the winter months when westerly and northwesterly winds flow, a study conducted by experts from CPCB and IIT-Delhi had found.
First Published: Aug 05, 2018 11:48 IST