The Delhi government issued a warning for a “critically polluted period ahead” as the capital on Thursday recorded its worst air quality since February.
The National Air Quality Index showed that pollution levels were “severe” at Anand Vihar, R K Puram and Punjabi Bagh. The air quality at Dilshad Garden, Dwarka and Mandir Marg stations was “very poor”.
The low wind speed, high humidity and farm fires in Punjab and Haryana turned Delhi’s air toxic on Thursday and particulate matter was responsible for the high pollution levels at all stations. Delhi recorded a maximum humidity of 94 per cent on Thursday.
“Ambient air is influenced heavily by farm fires, industrial emission, operation of more than 4,000 brick kilns and massive construction activities in the NCR. Major farm residue fires have been reported recently in Punjab and Haryana. Delhi, being on the down-wind direction, has been impacted severely. Due to this, the city may face a critically polluted period in the coming days,” said a statement issued by the government.
High humidity, low temperatures and low wind speed contribute to the increase in air pollution levels as these allow concentration of pollutants. For example, the wind speed at RK Puram on Thursday was between 0.3 and 1.5 metres per second.
“Such a low wind speed is not effective in dispersing pollutants. It was the primary reason behind the poor air quality,” said Gurfan Beig, a scientist at the System of Air Quality and Weather Forecasting and Research, Pune.
Ahead of Diwali on Sunday, the organisation is coming up with a special air pollution forecast and a tracker on Friday. According to its current forecast, while Delhi’s average air quality was very poor on Thursday, it will be severe on Saturday.
According to data collected and analysed by the Delhi Pollution Control Committee (DPCC), Diwali has got more polluted every year since 2010, despite government efforts.
On Diwali, the DPCC data says, the air quality is worst between 10 pm and 6 am the next morning.