Burning eyes, choking lungs: Here’s what Delhi looks like as air pollution rises

Dense smog continued to engulf the national capital for the second day, even as temperatures dipped and air quality levels deteriorated.

A thick blanket of haze hung low over Delhi for the second day on Tuesday, as air quality levels deteriorated and visibility plunged.

The Indian Medical Association said Delhi was witnessing a “public health emergency” and has appealed to the government to stop outdoor sports and other such activities in schools to protect the health of children.(Burhaan Kinu / HT Photo)

The Central Pollution Control Board (CPCB) identified four reasons for the sudden onset of pollution. Temperature, wind speed, relative humidity and atmospheric boundary layer had worsened Delhi’s air, CPCB experts said. Conditions are unlikely to improve over the next few days, they said.

“Meteorological conditions were such that all the local pollutants got trapped and lingered in the air. These four parameters had a direct impact on the pollution,” said D Saha, head of the air quality laboratory of CPCB.

Temperature dipped across Delhi-NCR on Wednesday. In Delhi the lowest temperature was 14 degree Celsius, two degrees lower than Tuesday. (Burhaan Kinu / HT Photo)

Wednesday became the coldest of the season so far with minimum temperature at 14 degree Celsius. Tuesday was the second-coldest day of the season with the temperature dropping to 16.1 degrees Celsius.

People in the capital are either using face masks or cloth to protect themselves from the toxic haze. (Burhaan Kinu / HT Photo)

On Monday afternoon, when temperature was around 30 degrees Celsius, PM2.5 level was just twice the permissible limit. But at 5am on Tuesday, when the temperature dropped to around 16.1 degrees, the PM2.5 level shot up by 9-10 times the permissible limit.

Officials said the average air quality index (AQI) — the measure of pollutants in the air — shot up to 463 on Wednesday, compared to 448 on Tuesday. (Sonu Mehta / HT Photo)

Another key reason for the haze in the capital is poor wind speed. While Delhi needs a minimum wind speed of 5 m/s to disperse trapped pollutants, the wind speed dropped to less than 1 m/s between 4am and 5am on Tuesday. The levels of PM2.5 were at least 10-15 times the permissible limit during this hour at stations such as DTU, Mathura Road and Delhi University’s North Campus.

In view of the severe pollution levels in the city, Delhi government ordered primary schools to be shut down on Wednesday. (Burhaan Kinu / HT Photo)

“The condition was aggravated by north-westerly winds, which are bringing in smoke from the stubble burning regions of Punjab and Haryana. The south-easterly winds are helping the moisture to build up. We apprehend that similar conditions would prevail over the next two to three days,” said A Sudhakar, member secretary of CPCB.

Traffic police cops wear masks as they manage traffic amid heavy haze at Ashoka Road in New Delhi. (Burhaan Kinu / HT Photo)

The atmospheric boundary layer (ABL) also plays a key role in determining the level of pollution. ABL forms the ceiling within which air circulates and Air quality improves when the height of ABL is more and pollution rises when it is low.

The humidity level in Delhi was recorded at 98 per cent at 8.30am on Wednesday. (Burhaan Kinu / HT Photo)

Pollution also increases as relative humidity builds up because high moisture helps to trap air and retain more pollutants. Over the past few days, easterly winds increased the moisture in Delhi’s air. In morning hours, when humidity was at its peak, pollution shot up.

The Indian Medical Association (IMA)asked people to stay indoors and refrain from physical activity. (HT Photo)

CPCB data shows humidity level was at its peak between 3am and 8am on Tuesday. During these hours, PM2.5 levels shot up by more than 10 times in almost all stations across Delhi.