Between 2010 and 2020, no let-up in transport sector emissions in Delhi

According to Beig, although emissions have not declined, there seems to be a marginal improvement in annual averages (of particulate matter levels) in Delhi. “This could be due to short-term, temporary measures like the Graded Response Action Plan. But, for a permanent solution, mitigation needs to be done by taking long-term steps so emissions from the source are reduced, rather than emissions being reduced by way of imposing stringent restrictions on a temporary basis.”

This could include steps like switching from fossil fuel-based vehicles to electric ones, he added.

The decadal change in emissions was estimated by comparing emission-related information from SAFAR in 2010 with data from 2020.

While the paper said decadal growth in PM 2.5 and PM 10 levels was found to be 31% and 3% respectively, Beig said an additional category of ‘others’ was included in the 2020 estimation; this includes emissions from sources like municipal solid waste burning and construction.

“This category was not included in 2010 as it was hard to get activity data at that time. However, if you recalculate emissions by incorporating that data, it is a marginal increase in both PM 2.5 and PM 10 in 2020 compared to 2010,” he added.

The bottom line? There has been no decline in emissions, Beig explained. “If emissions from biofuel or dust have declined, transport emissions have increased, which levels it off,” he said.

In addition to contributing to particulate matter and gaseous pollutant levels, combustion of fuel in vehicles also emits black carbon which can absorb energy from the sun and contribute to warming. This contribution from the transport sector has also increased from 2010 to 2020.

The paper said there’s been an increase of 39% in emission load from the transport sector as compared to a 36% increase in the industrial sector, and a decrease of 23% in windblown road dust emissions.

“Due to the penetration of LPG in slums, cooking-related emission has improved significantly, as is also the case in the residential sector,” the paper read.

“There is an increase in traffic congestion, but better paved-road conditions and road shoulder maintenance have resulted in a decrease in emission load from windblown road dust in the last decade,” it added.

PM 2.5 emissions in 2020 were estimated to be 123.891 gigagrams per year, with the single highest contribution of 41.369 gigagrams being from the transport sector. PM 10 emissions were 243.649 gigagrams in 2020, with ‘windblown road dust’ contributing the largest amount of 99.975 gigagrams to this. Carbon monoxide emission was found to be 799.023 gigagrams, with transport contributing 540.1 gigagrams to this, while emission of nitrogen oxides was 488.963 gigagrams in 2020, with the transport sector contributing 342.65 gigagrams to this. Of the 730.093 gigagrams per year of volatile organic compounds, 709.38 gigagrams came from the transport sector.

A total area of 70 kmx65 km covering Delhi and adjacent parts of NCR was considered for the estimation of emission inventory for eight major pollutants, and primary activity data of sources was generated through a field campaign.

On PM 10 emissions, the paper noted, “A recent rising trend of vehicle numbers along with vehicles from surrounding states on Delhi roads in the last 10 years has put tremendous pressure on road network expansion, leading to heavy traffic congestion. All major traffic junctions are experiencing high emission loads. However, the highest-emitting grids… are also found in small patches driven by sources like WTE (waste-to-energy) plants and industrial practices followed by municipal solid-waste burning as well. It has been found that Okhla region is one of the highly polluted hotspots where WTE plants, municipal solid waste burning, and windblown road dust are dominating sectors responsible for elevated PM 10 emissions,” the paper said.