Delhi continues to choke as ‘severe’ air quality continues

Air quality in the Capital, after a two-day respite, continued to remain in the “severe” category on Saturday, as western disturbances in the region brought down the wind speed, effectively trapping pollutants within Delhi. Thursday’s improvement in AQI had broken a five-day streak of “severe” air that the Capital had been experiencing, which came as a result of an increase in wind speed.

The prevailing meteorological conditions also led to a rise in the temperature, with Delhi clocking a maximum temperature of 29.4°C, which was over 2°C higher than the day before and three degrees above the normal for this time of the year, according to the India Meteorological Department (IMD).

The air quality index (AQI) of Delhi was 412 (“severe”) at 4pm, according to the 24-hour average data shared by the Central Pollution Control Board (CPCB) in its daily bulletin. This was markedly above the AQIs of 371 (“very poor”) and 393 (“very poor”) recorded at the same time on Thursday and Friday, respectively, even as the AQI started deteriorating on Friday night, reaching 414 (“severe”) around 10pm. However, by Saturday night, the AQI improved to “very poor” level, albeit with marginal improvement, clocking a reading of 395, on the cusp of “severe”.

CPCB classifies AQI between 0 and 50 as “good”, between 51 and 100 as “satisfactory”, between 101 and 200 as “moderate”, between 201 and 300 as “poor”, between 301 and 400 as “very poor”, and over 400 as “severe”.

Neighbouring cities fare better

NCR cities in Haryana and Uttar Pradesh fared better on the day, as Gurugram recorded an AQI of 265 (“poor”)—the best in the region—followed by Greater Noida, which clocked 307 (“very poor”), Noida, which clocked 322 (“very poor”) and Ghaziabad, which clocked 339 (“very poor”).

Experts said that the air quality is likely to improve soon due to an increase in wind speed, and the temperature will also dip over the next week after a potential increase on Sunday.

“A western disturbance started influencing the region on Friday, which interrupted the northwesterlies and brought down the wind speed. The wind speed, on Saturday, was 2-4 kmph. The low wind speed could not dissipate pollutants and as a result, the AQI went up,” said Mahesh Palawat, vice president at Skymet.

Of the 31 AQI monitoring stations from which Delhi data was compiled, 26 stations had “severe” AQI at 11am. However, this improved in the second half of the day, with 19 stations clocking “severe” air at 4pm. By 6pm, Delhi’s average AQI was 405 (“severe”), at 9pm, it was 396 (“very poor”) and at 10pm, it was 395.

According to a forecast by the Air Quality Early Warning System (AQEWS) for Delhi, the air quality is expected to return to the “very poor” category by Sunday. “The air quality is likely to be in very poor category from Sunday to Tuesday. The outlook for subsequent six days is that the air quality is likely to be in very poor category,” said the AQEWS bulletin on Saturday evening.

Mercury rises

The temperatures in Delhi clocked a rise due to meteorological factors on the day, according to IMD data.

The minimum temperature increased marginally, from 11°C on Friday to 11.4°C on Saturday, which coincided with the normal temperature for this time of the year. The maximum temperature increased from 27.2°C on Friday to 29.4°C on Saturday, which was three degrees above the normal temperature for this time of the year.

Skymet’s Palawat said, “The western disturbance is passing eastwards. The northwesterlies will continue to impact the region. Once the western disturbance has passed, the wind speed should pick up, resulting in dip in temperature again.”

An IMD official said that a shallow to moderate fog is likely to form on Sunday morning and persist till the night. IMD has forecast the maximum to remain around the 27°C mark on Sunday and then start dipping again. The minimum, too, might touch 12°C on Sunday, the official said.

The highest maximum temperature on the day was recorded at the Pitampura weather station, at 30.1°C. The lowest minimum temperature on the day, 10°C, was recorded at the Ayanagar and Lodhi Road weather stations. The visibility at Safdarjung station was 300 metres at 6.30am, according to IMD.

Meanwhile, neighbouring Gurugram recorded a maximum temperature of 28.7°C and a minimum temperature of 11.6°C on the day. Gautam Budh Nagar district in Uttar Pradesh, which comprises Noida and Greater Noida, recorded a maximum temperature of 27.8°C and a minimum temperature of 11.9°C.