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Air quality continues to deteriorate in Delhi, PM10 levels breach 400 mark

Experts hoped the pollution levels could go down over the next two days as the wind speed was expected to increase. Delhi could also receive a spell of very light rain in the middle of the week

delhi Updated: Dec 02, 2017 09:38 IST
Hindustan Times
delhi,delhi news,weather
If the level of PM10 and PM2.5 hits the 500 and 300 mark, respectively, and stays there for at least two days, emergency measures such as road rationing, shutting down of schools and ban on construction activities would be introduced.(REUTERS)

New Delhi

Delhi’s air quality deteriorated further on Friday with the level of PM10 breaching the 400-mark for the first time since November 14, when the city had just come out of the week-long haze and severe levels of pollution.

Experts hoped the pollution levels could go down over the next two days as the wind speed was expected to increase. Delhi could also receive a spell of very light rain in the middle of the week.

In the wake of the deteriorating air quality, the South Delhi Municipal Corporation’s mayor, Kamaljeet Sehrawat, distributed air purifiers to four primary schools.

Delhi’s average Air Quality Index on Friday was 343, marginally lower than Thursday’s count of 360. The AQI had been fluctuating over the past few days. On Monday it had touched 361. Thereafter it had come down to 307 on Tuesday and 334 on Wednesday.

The level of PM10, however, shot up to 412ug/m3 around 2 pm on Friday from 379ug/m3 around the same time on Thursday. This is four times above the permissible limit of 100ug/m3.

“Such high concentrations of PM10 were last seen on November 14 when PM10 levels were recorded to 413ug/m3. Delhi at that time had just come out of the week-long severe levels of air pollution. The haze continued from November 7 to November 13. On November 14, the air quality improved to some extent,” said a scientist of the Central Pollution Control Board (CPCB).

The level of PM2.5, however, fluctuated throughout the day and was comparatively lower than what it was on Thursday. It had hit a peak of 230ug/m3 on Thursday. On Friday, the highest concentration of PM2.5 was recorded to be 226ug/m3.

According to the Graded Response Action Plan, if the level of PM10 and PM2.5 hits the 500 and 300 mark, respectively, and stays there for at least two days, emergency measures such as road rationing, shutting down of schools and ban on construction activities would be introduced.

Experts said that fluctuation in the weather systems, particularly in the wind speed and wind directions, is affecting the pollution levels.

“Sometimes, moisture-laden winds from the south-east are gushing in. This has increased the moisture content in the air. The moisture trapped the pollutants and they started accumulating,” said D Saha, head of the air quality monitoring laboratory at Central Pollution Control Board.

The local met department, however, says the wind speed will pick up over the next 48 hours and there could be light rain in Delhi-NCR on December 5.

“The average wind speed, which was around 10km/hour till Friday, is expected to increase to 15 km/hour over the next two to three days. This could help in cleaning Delhi’s air further. We are also expecting some very light rain on December 5,” said Kuldeep Srivastava, a scientist with the regional weather forecasting centre.

First Published: Dec 01, 2017 23:12 IST