After cleanest Nov day in years, Delhi sees worst pollution of the season

NEW DELHI: In one of the most dramatic deterioration in the city’s air quality, Delhi saw its most polluted day of the season on Monday just 24 hours after having recorded the cleanest air in November in at least three years.


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Air quality plummeted from an AQI of 171 (moderate) recorded on Sunday to 426 (severe) on Monday, a difference of more than 250 points. Residents of Delhi and NCR cities woke up to a toxic haze on Monday morning along with a burning sensation in the eyes brought on by a sudden rise in incursion of pollutants from crop-burning in Punjab-Haryana, a drop in temperatures, a rise in moisture levels and related meteorological conditions.

Experts said Monday’s conditions were indicative of what NCR residents can expect in the coming days. Forecasts show that while some improvement could take place on Tuesday, the effect will be minimal with high moisture content and low temperatures likely to continue.


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CPCB officials said a mixture of factors led to the sharp fall in air quality.

“Sunday was the cleanest November day in the last three years in terms of AQI and the sudden increase in pollution was due to three factors. The withdrawal of the western disturbance led to an increase in moisture content which is trapping pollutants in Delhi. While localised sources are playing a part too, the wind direction has also changed to north-westerly which is bringing crop burning pollution to Delhi. We are also seeing a drop in temperatures which is further going to make dispersal of pollutants difficult,” said Prashant Gargava, member secretary, CPCB.

CPCB’s central control room data showed how the pollution levels spiked in a matter of hours. Delhi NCR’s average PM 2.5 readings at 5pm on Sunday were just 77 micrograms per cubic metre. Just 24 hours later, it was recorded at 351micrograms, almost six times the safe standard. Similarly, the average PM 10 levels which were recorded at 162 micrograms per cubic metre at 5pm on Sunday were showing a reading of 486 micrograms at 5pm on Monday — close to five times the safe standard.

By 8pm on Monday, the average PM 2.5 levels had also been over the “emergency” mark of 300 micrograms per cubic metre under GRAP for 10 hours. If the levels remain over this mark for 48 hours, a host of measures under the “emergency” phase of GRAP can be implemented which includes stopping entry of trucks into Delhi and implementation of oddeven vehicle restrictions.

SAFAR’s forecast shows Delhi’s air quality is likely to go back to “very poor” on Tuesday. However, pollution levels will still remain high. “Although there is lot of moisture in the air after the withdrawal of the westerly disturbance, but as the drop in temperature was not significant, it may dry up fast. Wind speeds at transport height are also likely to reducewhich will stabilise pollution,” said a SAFAR analysis on Monday.

CSE’s Anumita Roy Chowdhury said people need to reduce use of private vehicles as traffic on the roads has increased substantially in the run-up to Diwali – adding to the spike in pollution.

Residents around the capital, too, felt the ‘change’ in air quality with most complaining of an irritation in their throat, eyes or skin. “I have a running nose all day and have been sneezing. The cool temperature and dust allergies are affecting my health. Good thing is I have two days holiday for Diwali from tomorrow so will stay indoors and hopefully fit,” said Shekhar Sood, an East of Kailash resident who travels daily to ITO for work.