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Tuesday, December 10, 2019

After light rain, air quality dips to ‘very poor’ in Delhi

The IMD said south-southeast wind of 16 km/hr were recorded in the capital Thursday, which could reduce in the evening and become as low as around 3-4 km/hr in the morning hours.

By: Express News Service | New Delhi | Updated: November 8, 2019 10:28:34 am
delhi pollution, delhi air, PM 2.5 in delhi air, PM 10 in delhi air, drop in PM 2.5 in delhi air, delhi pollution, delhi pollution today, delhi aqi today, delhi air quality today, delhi weather, delhi rains, delhi city news A slight drizzle in the morning hours increased moisture content in the air, which pollutants got attached to. (Express photo: Abhinav Saha)

A brief improvement in the capital’s air quality ended Thursday after it dipped to the ‘very poor’ range and a layer of “smoke” surrounded parts of the NCR.

Dispersion of pollutants, despite high wind speed, remained low as a slight drizzle in the morning hours increased moisture content in the air, with which pollutants got attached, experts said. “Light rainfall Thursday morning increased moisture content in the air hindering dispersion of pollutants,” said Kuldeep Srivastava, scientist at the India Meteorological Department.

As per the Central Pollution Control Board (CPCB), Delhi’s average air quality index (AQI) on Thursday was 309 in the ‘very poor’ range. A day earlier, it had improved to 214 (‘poor’) after witnessing one of the worst air quality episodes this season on Sunday, when the AQI had crossed emergency levels and was recorded at 494 in the ‘severe’ category.

However, real time air quality data from CPCB Thursday showed the city’s AQI was deteriorating as the day progressed. At 10.30 am it was around 250, but spiked to 273 around 1.30 pm. Around 4 pm, it reached 309 and fell further to 343 by 9.30 pm.

Air quality in NCR towns also remained in the ‘very poor’ range except in Gurgaon, where AQI was 284 (‘poor’).

The IMD said south-southeast wind of 16 km/hr were recorded in the capital Thursday, which could reduce in the evening and become as low as around 3-4 km/hr in the morning hours.

A shallow to moderate fog is likely to be noticed in Delhi-NCR Friday until 10 am during which visibility would be around 200-300 metres, IMD said. With high moisture content in the air during this time, and low wind speed, pollution levels may spike before cloud cover over Delhi starts receding by noon and wind speed picks up again later in the day.

The share of pollution from stubble burning in Punjab and Haryana has dipped significantly and is predicted to be 3% Friday, according to the central government’s SAFAR air quality monitoring system. More than 42,000 farm fires have been recorded in Punjab between September 23 and November 6, much higher than over 30,000 fires recorded last year in this period. In Haryana, over 5,400 fire counts have been recorded as of November 6, a reduction of 472 from last year.

However, since the wind direction is south-southeast, transport of PM 2.5 from stubble burning is unlikely, experts said, unless it changes to northwest direction. A Delhi environment official said, “There are no external pollutants in the air… A situation similar to last Sunday is unlikely Friday.”

Pollution from stubble burning in Delhi’s air is expected to go higher by Saturday, when the wind direction changes. Air quality is also expected to deteriorate to the higher end of the ‘very poor’ category by Saturday, SAFAR said.

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