Cocktail Of Smoke, Dust, And Fumes: What Delhi Is Breathing As Air Quality Dips To 'Severe'

Delhi experienced its first 'severe' air quality day of the season on Thursday, with further deterioration on Friday.

The air quality in the National Capital was affected by a combination of elements, including sluggish wind speeds and the encroachment of smoke from agricultural fires, which exacerbated the effects of the city's own pollution.

On Friday, the air quality index (AQI) hit the 460 mark, entering the 'severe plus' category of air pollution.

The worsening air quality triggered a fresh set of measures by the authorities in an attempt to reduce the air pollution in Delhi and adjoining areas of Noida and Gurgaon, including closing of schools and ban on non-essential construction.

Earlier, throughout the day on Thursday, the situation progressively declined, with air quality index readings rising from 351 at 10 am to 402 by 5 pm, and worsening to 418 by 9 pm.

Airborne pollutants cast a sepia-like hue over the city, resulting in persistently low visibility throughout the day.

IMD scientist Kuldeep Srivastava reported that early morning visibility was limited to 500 meters at the Safdarjung weather station due to light fog, which slightly improved to 700 meters by mid-afternoon. At Palam, the visibility was consistently around 1,000 meters from morning till 3 pm.

Srivastava explained that the morning's high relative humidity likely led to the formation of light fog, a result of water vapour condensing. However, by afternoon, humidity levels dropped to about 55 per cent.

“Calm conditions are prevailing. At Palam, winds were from the northwest; at Safdarjung, there were easterly winds. The speed was just 2 to 3 kmph at both stations,” Srivastava said, Indian Express reported.

Gufran Beig, the founding project director of SAFAR and a chair professor at the National Institute of Advanced Studies, pointed out that the high incidence of crop residue burning has significantly contributed to the pollution.

He noted that current meteorological conditions are conducive to the gathering of pollutants.

Low visibility is on account of intrusion of particles. Winds are calm even at a height of half a kilometre from the ground, and that is resulting in the suspension of particles and low visibility…," he said.

Beig also mentioned that at this time of year, the wind typically shifts to a north-northwesterly direction.

"The temperature is not that low, but major factors now are transport level wind direction and speed that is bringing pollutants into Delhi - stubble-related emissions travel at half a km to one km above the surface," he added.

According to the officials cited in the IE report, wind speeds between 10-12 kmph are typically effective in scattering pollutants. However, conflicting wind directions can prevent this dispersal. Additionally, warmer temperatures cause the air to heat and ascend, aiding in the spread of pollutants.

While strong winds or rainfall may have helped to clear the air, neither are on the forecast for the next few days.

According to a forecast issued by the Air Quality Early Warning System for Delhi, wind speed is likely to be around 4 to 10 kmph on Friday with shallow fog in the morning, while it is likely to be around 6 to 8 kmph on Saturday and Sunday.

The air quality woes extended to other regions of the National Capital Region, with the AQI reaching the 'severe' bracket as well—Greater Noida recorded an AQI of 414 and Jind hit 415 at 5 pm.

Data from the Indian Agricultural Research Institute revealed that Punjab saw 1,921 cases of crop residue burning on Wednesday, marking the fourth consecutive day with counts surpassing 1,000. However, the Punjab Remote Sensing Centre has indicated a delay in Thursday's report.

The Indian Institute of Tropical Meteorology's Decision Support System reported that biomass burning accounted for 18.31 per cent of Delhi's PM 2.5 pollution levels on Wednesday, a significant increase from Tuesday's 7.175 per cent.

It estimated that the contribution on Thursday is likely to be around 22 per cent, that on Friday is likely to be around 21.32 per cent, and that on Saturday could be around 15.115 per cent.

The Central Pollution Control Board identified PM 2.5 as the main pollutant in Delhi on Thursday.