Delhi's AQI hits 400 again, may get worse with fireworks on new year
The noxious conditions, forecasts warned, are likely to persist over at least three more days, with air quality likely to worsen further.
Delhi residents once again woke up to choking conditions on Saturday morning, as the city’s air quality index (AQI) drastically worsened to 400, just shy of the “severe” mark, with the day temperature remaining low even as the sheet of dense fog that had engulfed the city for the past few days finally eased.
Read here: Foggy conditions prevail in Delhi with minimal visibility; AQI still ‘very poor’
The noxious conditions, forecasts warned, are likely to persist over at least three more days, with air quality likely to worsen further if people decide to burst firecrackers New Year’s Eve.
The 24-hour average AQI in Delhi touched 401 around noon on Saturday, in the “severe” zone, before dropping to 400 (in the “very poor” category) by 4pm, which is considered the official reading of the day, according to data furnished by Central Pollution Control Board’s national bulletin.
The city’s AQI at 4pm had been 382 (very poor) on Friday, and was 358 (also very poor) the day before that, according to CPCB’s daily bulletins.
An IMD official said the deterioration in air quality appeared to be on account of the low day-time temperature that the city has seen over the last two days. “Low temperatures, and reduced wind speeds lead to a stagnation of the atmosphere. With almost no sunlight penetrating even during daytime, wind speeds stayed low, not allowing pollutants to disperse,” the official said.
It also seems unlikely that conditions will improve soon, according to forecasts.
“Delhi’s air quality is likely to remain in the ‘very poor’ category from December 31 till January 2. As weather conditions are not favourable for effective dispersion of pollutants, emissions from firecrackers, if burnt on December 31, may deteriorate air quality,” said forecasts by the Centre’s Early Warning System (EWS) – a forecasting model under the Union ministry of earth sciences.
CPCB classifies an AQI 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”.
Fog eases, but days remain cold
Despite the rise in pollution levels, the dense fog that had engulfed Delhi over the past five days – throwing flights, trains and road traffic into chaos – finally appeared to ease. “Moderate” fog was recorded in the city on Saturday. The India Meteorological Department (IMD) said the lowest visibility was recorded at 200metres at Safdarjung on Saturday, with this being even better at Palam, where the visibility did not dip lower than 500m.
The improved visibility meant Delhi’s Indira Gandhi International Airport reported no flight cancellations or diversions, with only 10 flights delayed early on Saturday morning. Northern Railway said at least 30 trains – to and from Delhi – were delayed by more than one hour.
A dense fog over the past few days caused havoc for passengers coming in and out of Delhi ahead of New Year’s Eve with hundreds of flights and trains off schedule or outrightly cancelled. Around 25 flights were delayed on Friday, while this number stood at over 100 on Thursday. Meanwhile, at least 11 trains were delayed by more than one hour on Friday and the figure was over 30 on Thursday.
Saturday’s maximum temperature was 20.3 degrees Celsius – around normal for the season. It was 19.8°C a day earlier, the lowest it has been so far this winter. The shivering conditions in the day were mainly due to a thick layer of fog persisting in the upper levels of the atmosphere throughout Friday. IMD officials said this same phenomenon was not as dominant a factor on Saturday, IMD officials said.
Low daytime temperatures can exacerbate people’s exposure to the cold and generally make the winter feel more intense since this is when people are usually outside of the comfort of their homes.
“While we still saw fog across the northern plains, the density and impact was far less and visibility had already improved over 900 metres in places by 9am,” said an IMD official, stating with sun coming out in parts of Delhi, the maximum also did not plummet further.
Delhi’s minimum temperature, meanwhile rose even further on Saturday, making nights warmer than usual for this time of the year. The minimum was recorded at 11.8°C on Saturday – five degrees above normal. It was 10.7°C a day earlier.
Read here: City’s air quality at 178, four stations record ‘poor’ AQI with BKC at 272
“When fog is prevalent through the night, the minimum rises, as the it prevents substantial heat from being lost into the atmosphere at night-time. If skies are clear, the heat is lost in a matter of hours and mercury dips sharply,” said an IMD official.
IMD forecasts the maximum and minimum to hover around 19°C and 11°C respectively on Sunday, with chances of moderate to dense fog in the morning.