The Delhi government’s real-time source apportionment portal — R-Aasman — has resumed sharing sources of pollution impacting the Capital’s air after eight days when the website was not updated. The last update before this was on December 12.
Meanwhile, the city’s air quality turned “very poor” on Thursday (361) from “poor” (285) on Wednesday even as the source apportionment data showed that vehicular emissions and biomass burning were the two biggest sources of pollution — contributing to around 70-80% of the PM2.5 levels.
The data showed the contribution of vehicles to PM2.5 concentration was 35% on Thursday at 5pm while the contribution of biomass burning was 34%. Burning of plastic and waste contributed another 6%. It also showed the previous day’s contribution at the same time as 61% from vehicles, 20% from biomass burning and 1% from waste burning. However, the website said that secondary aerosol data has not been shared since November 30.
A senior Delhi Pollution Control Committee (DPCC) official said data over the last week was not being generated due to a technical problem, which has now been rectified by IIT Kanpur, which operates the real-time lab in coordination with DPCC.
“Due to an instrument becoming faulty, the data was not being generated. IIT Kanpur was asked to take corrective action and the website is operational again,” said the official, adding that secondary aerosol data calculation will also resume soon.
Biomass burning includes burning of firewood, dung and leaves in the open — a common occurrence in winters, when temperatures start to dip at night. Secondary aerosols are sulphates, ammonia and nitrates released into the atmosphere following the interaction of gases released by combustion sources like power plants, brick kilns, industries, and refineries.
Forecasts show Delhi’s air quality would remain “very poor” over the next three days.
“Delhi’s air quality is likely to remain in the ‘very poor’ category from December 22 to December 24. The outlook for the subsequent six days shows the air quality is likely to remain between ‘very poor’ and ‘poor’,” said the Early Warning System (EWS) for Delhi, a forecasting model under the ministry of earth sciences.
Dipankar Saha, former head of Central Pollution Control Board’s air laboratory said that data transparency is important and reiterates a known fact — that biomass burning is on the rise. “We see it, particularly in December and January when a lot of firewood is burnt to stay warm. Similarly, other items like leaves and even waste are set on fire at night. This contributes to local air pollution and if instances are high, to the overall pollution of Delhi,” Saha said.
Rampant instances of biomass burning were also flagged by DPCC to the Municipal Corporation of Delhi on Tuesday. In a letter to MCD, DPCC flagged 43 hot spots across the city, where biomass burning has been detected regularly over the last year. MCD was asked to take action to thoroughly investigate these hot spots. DPCC had said the hot spots were identified using complaints on the Green Delhi app between December 2022 and December this year.