Delhi’s air quality was in the upper end of the ‘very poor’ category on Wednesday morning, recording a marginal improvement in comparison to Tuesday. The 24-hour average air quality index (AQI) stood at 389 (very poor) at 7am, while it was 397 (same category) at 4pm on Tuesday.
Forecasts by the India Meteorological Department (IMD) showed that there will not be any significant change in weather over the next three days, with low temperatures and early morning calm-wind conditions likely to persist. Between noon and 5pm, Delhi should record average wind speeds of 6-8kmph, it said.
Kuldeep Srivastava, scientist at IMD, said the predominant wind direction was northwesterly on Tuesday, with winds remaining calm both on Monday night and in the early hours of Tuesday. However, the wind speed picked up for a brief while post noon, becoming calm once again by yesterday evening.
“Similar conditions are expected on Wednesday and Thursday too. The only difference will be that while wind direction will remain northwesterly on Wednesday, it should switch to easterly by Thursday.” Srivastava said.
The visibility at Palam meanwhile stood at 600m at 7am on Wednesday morning. It had dropped to 500m at Palam on Tuesday, before gradually improving to 1,800m during the day.
Forecasts by the Early Warning System (EWS) for Delhi said the capital’s AQI is likely to be ‘very poor’ till Friday. “Delhi’s air quality is likely to remain in the ‘very poor’ category from Wednesday till Friday. The outlook for the subsequent six days shows air quality is likely to remain largely in the ‘very poor’ category,” EWS said.
The Decision Support System (DSS), which estimates the contribution of different sources in Delhi’s PM 2.5, on Tuesday said Delhi’s vehicular sector was likely contributing around 18.8% to the city’s PM 2.5 concentration, with around 12.5% estimated to be coming from biomass burning, around 4.7% from industries in Delhi and around 4% from the residential sector. Another 19.1% is estimated to be coming from ‘other’ sources – unaccounted sources beyond Delhi’s border, it said.
Forecast by DSS for Wednesday said the estimated contribution of biomass burning should be 14.8%, followed by 14.5% coming from vehicular emissions.
Delhi’s average AQI shot up post Diwali yet again as residents flouted the Supreme Court’s order by bursting firecrackers. The capital’s 24-hour average AQI was 218 (poor) on Sunday, but that spiked by 140 points to touch 358 (very poor) at 4pm on Monday. By 10pm on the same day, the average AQI was ‘severe’, with a reading of 403.
Interestingly, the average AQI stood in the range of 360-370 on Tuesday morning, as per CPCB’s Sameer app, giving the impression that the air quality had improved. However, a closer look showed that the app was displaying data from only 9 out of Delhi’s 40 stations, with no data being made available from the 24 Delhi Pollution Control Committee (DPCC) air quality monitoring stations.
The DPCC later said this happened due to a server problem at their end, which was preventing real-time data from reaching the CPCB. This problem was fixed just in time for the day’s daily bulletin released at 4pm, it said. In all, the data was missing for eight hours, from 7am till 3pm, during which the average AQI was below 370. This then shot up to Tuesday’s actual average AQI of 397 at 4pm.
There was no such problem on Wednesday morning though as the data on the app was available from 36 stations in total. Nehru Nagar (433) was the worst impacted location, followed by Jahangirpuri (432).
Delhi’s maximum was recorded at 25.9 degrees Celsius on Tuesday, three degrees below normal. The minimum stood at 12.0 degrees Celsius, two notches below normal. According to IMD, the maximum should remain around 26 degrees Celsius on Wednesday, while the minimum is likely to be around 11 degrees Celsius.