Shroud of smog envelops Delhi amid dirty air | Latest News Delhi
Delhi on Thursday morning was blanketed by a thick, grey haze, which took around three hours to dissipate as the city’s residents, particularly children and the elderly, struggled with a racking cough and a burning sensation in the eyes — annual complaints for the Capital in the winter season.
In addition, a combination of low wind speeds, the presence of moisture in the air, and a toxic cocktail of pollutants — from both local sources and from neighbouring states — meant the Capital’s air quality index (AQI) reading was in the “very poor” zone at 377 — 25 points higher than the 352 recorded the previous day, and tethering close to “severe” levels.
By 10pm, AQI was 383.
Forecasts show that unfavourable meteorological conditions are likely to persist in the coming days, and the Capital’s pollution levels are likely to remain in the “very poor” category till at least the weekend.
The Central Pollution Control Board (CPCB) classifies an air quality index (AQI) reading between 0-50 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”.
Winds remained calm through the day, unable to disperse pollutants, while moisture levels oscillated between 59% and 94% over a 24-hour period, though mostly remained below 75% through most of the day. At the same time, the haze in the morning hours meant Delhi’s visibility dropped to the 800m mark for a third day in a row.
Meteorological experts said with pollution levels fairly high and moisture levels below 75%, the haze was likely smog — not fog — for a majority of the day.
“For the last three to four days, pollution levels have been high and the relative humidity has largely remained below 75%. In weather terminology, we call it fog when visibility drops below 1,000 metres and though there is some moisture in the air, pollutants are the dominant factor when it comes to low visibility at present. It is safer to say we are recording smog, even though there is no official definition of the term,” said Mahesh Palawat, vice president at Skymet meteorology.
Separately, India Meteorological Department (IMD) director general M Mohapatra said the Met has been using both terms — smog and fog — in their forecasts for Delhi. “Visibility has to be lower than 1,000 metres for fog, but when moisture is lower than 75%, it can be called smog, as moisture is low,” he said.
IMD data revealed that the wind direction over Delhi has also remained variable over the last three days, oscillating between northwesterly, easterly and southeasterly. Upper-level winds, which blow at heights of 1km and more above the surface, have predominantly been northwesterly, allowing stubble smoke from northern states to reach the Capital.
“It (the haze) is a combination of local pollutants and stubble smoke. Since the surface level winds are calm, this is more visible and not dispersing,” Palawat added.
CPCB data showed on Thursday, both PM 2.5 and PM 10 were dominant pollutants at 4 pm. Out of the 40 AQI stations in Delhi, 12 were in the severe range at this time — at 435, Wazirpur was the highest, followed by Anand Vihar and Jahangirpuri (both 434).
Meanwhile, Delhi recorded yet another warm day on Thursday, as the city’s maximum temperature was at 31.7 degrees Celsius (°C) — two degrees above the normal for this time of the year, but 0.6 degrees lower than Wednesday. The minimum stood at 18°C, four degrees above normal and 0.7°C higher than the previous day’s low of 17.1°C.
Forecasts show the maximum and minimum temperatures are likely to hover around 33°C and 18°C respectively on Friday.
