Emissions of Delhi-NCR vehicles higher than approved limits in lab settings: Study | Latest News India

Real world emissions even from vehicles, across fuel types, complying with the latest emission standard of Bharat Stage VI (BS VI) are higher than type approval limits, contributing to high pollution levels in Delhi NCR, a new report by The International Council on Clean Transportation (ICCT) has found.

The campaign captured over 100,000 valid measurements across 20 sites in Delhi and Gurugram. (Representative file photo)

This is particularly the case for high-use commercial vehicles; for instance, BS VI taxi and light good vehicle fleets were shown to emit 2.4 and 5.0 times more nitrogen oxides (NOx) emissions than the counterpart private car fleet.

The results based on a remote sensing based emissions monitoring study also challenge the notion that vehicles fueled by compressed natural gas (CNG) are a “clean” transportation alternative.

Across the range of BS VI vehicles measured fueled by CNG, emissions were 1.5–14 times greater than the type-approval limits, the study conducted in collaboration with Delhi Transport Department (DTC) and Gurugram deputy commissioner’s (GDC) office found.

Also Read: Delhi to soon get new environmental damage compensation penalty for e-waste violations: DPCC to NGT

For three-wheelers, private cars, taxis, light goods vehicles (LGVs), and buses, nitrogen oxides (NOx) emissions were found to be 3.2 times, 2 times, 4 times, 4.9 times, 14.2 times, and 1.5 times higher, respectively, than type-approval limits.

These findings suggest that the combined benefits of stricter emission standards and an accelerated shift to zero-emission vehicles (ZEVs), at least in the commercial vehicle category, ICCT has recommended.

Agencies like the Commission for Air Quality Management in NCR could implement policies such as a ZEV sales mandate and a combustion engine phaseout program targeted at highly polluting vehicle segments.

California for example has zero emission vehicle mandate on the supply side that vehicle manufacturers need to comply with.

Paris and London are implementing low emission zones within the city to push for switching to ZEVs.

As part of the study, exhaust emissions of NOx, carbon monoxide (CO), hydrocarbons (HC), and ultraviolet (UV) smoke, a proxy for particulate matter, were measured from several vehicle types: two- and three-wheelers, private cars, taxis, light goods vehicles (LGV), and buses.

The campaign captured over 100,000 valid measurements across 20 sites in Delhi and Gurugram and uncovered important patterns that can guide the development of targeted and effective policies to combat traffic-related pollution.

“We are seeing that NOx emissions need to be monitored very effectively from the transport sector because NOx contributes to secondary particulate matter (PM) and in turn high pollution levels in Delhi NCR,” said Amit Bhatt, India managing director ICCT in a press conference on Friday.

“The real world emissions of BS VI vehicles are found to be higher compared to the lab value mainly because of loading, road conditions, maintenance etc. It doesn’t reflect the emissions as measured in static conditions,” Bhatt explained.

ICCT measured emissions from all fuel categories– petrol (45%); CNG (32%) and diesel (23%).

“Diesel vehicles are performing poorly on PM and NOx but unfortunately CNG vehicles are also emitting equally high amounts of NOx on road,” said another expert from ICCT.

“It is evident that real-world emissions from transport vehicles differ significantly from their laboratory values. For the first time in India, we have collected significant emissions data from motor vehicles on the road and it is crucial to remember that what impacts our air quality is not the laboratory emissions, but the pollutants released by these vehicles when they are in operation. Therefore, it’s time to reimagine our emissions testing regime and aggressively push for the adoption of zero-emission vehicles,” Bhatt added in a statement.

“This important research clearly shows India and the rest of the world that compressed natural gas is not the clean alternative fuel which was promised. While Delhi battles with dirty air, a visible killer hanging over the city, the study has shown that this less visible but still deadly fuel is not the answer. For health and for the climate, the solutions to dirty air are to switch to walking, cycling, and shared electric mobility,” said Sheila Watson, Foundation for the Automobile and Society deputy director in a statement.

It is however important to note that vehicles produced to the newest emissions standard – BS VI – show significant improvements in tailpipe emissions across all pollutants and vehicle types measures.

For example, real-world NOx emissions from private cars showed a reduction of 81% and buses nearly 95% as compared to BS IV, ICCT said.

In 1998, the Supreme Court ordered that all public transport vehicles in Delhi that ran on diesel switch to compressed natural gas (CNG) by 2001. This included buses, three-wheelers, and taxis.

“While CNG has played a significant role in curbing toxic and carcinogenic particulate emissions from diesel vehicles in Delhi, the new assessment of the real world emissions shows that NOx emissions from on-road CNG fleet can be high. While CNG has been a transitional fuel, the solution cannot be substituting one transitional fuel with another to get cleaner emissions. But to move towards zero tailpipe emissions or electric vehicles,” said Anumita Roy Chowdhury, executive director, Centre for Science and Environment (CSE).

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