The New Delhi-based environmental think tank also said that a series of steps taken since last year, including restrictions on entry of trucks to Delhi, and a push for enforcement on waste burning and dust sources have started yielding results, showing a consistent decline in peak levels of air pollution.

CSE said the auto industry has taken a “reductionist” view of a claim made in a study by Indian Institute of Technology Kanpur that if vehicles contribute 20% of particulate matter (PM) 2.5—air pollutants that measure 2.5 micrometres or less—and cars account for 10% of it, then all cars account for 2-3% of PM 2.5 pollutants, with diesel cars’ share even smaller.

“Therefore, they claim that the contribution of cars to particulate load is so small that they do not merit any action. But industry fails to convey that cars emit more PM 2.5 than several other key pollution sources in Delhi and that they emit more NOx (nitrogen oxide) than several other key pollution sources in Delhi. This clearly brings out that Delhi cannot meet its clean air objective if stringent action is not taken on cars,” CSE noted, adding that the industry is underplaying carcinogenic and toxic effects of diesel emissions.

On 30 April, the Supreme Court banned diesel-fuelled taxis from plying in the national capital. The court also extended the stay on registration of diesel vehicles above 2,000cc capacity in the Delhi-NCR region until further orders.

Auto makers have been seeking a modification of the order pleading that other sources of pollution are far bigger culprits than diesel cars for pollution in the national capital.

“It is ironical that now that when action has started to show results to curb the killer air pollution in the city, detractors are out to derail the process. Instead of ensuring that the action builds up momentum quickly, motivated campaigns have been launched to subvert the process,” said CSE director general SunitaNarain while emphasizing that Delhi has to step up action on all key sources of pollution, including vehicles, to meet clean air targets throughout the year.

“Action to control air pollution has started and is showing results. But this needs to gather momentum. More needs to be done. This needs to be encouraged and not blocked with misinformation,” she cautioned.

CSE also claimed that there is clear evidence that with reduction in truck numbers, night pollution levels have also come down since last year.

The Supreme Court made it mandatory in December for taxis to shift to compressed natural gas, doubled the entry tax for trucks into the city and banned trucks registered before 2006 from plying on the city’s roads.

CSE also praised the Delhi government’s odd-even initiative saying that as an “emergency measure” it has prevented pollution from getting worse. So far the scheme has been implemented twice—from 1-15 January and 15-30 April.

“The odd and even scheme in two phases has shown that cutting down vehicle numbers can reduce exposure to toxic pollution and prevents the peaks from getting worse. But emergency action will have to be implemented with permanent measures for sustained gains,” the analysis added.

CSE also highlighted that governments in other countries are taking far more stringent action on vehicles, especially cars, than Delhi.

For instance, in Beijing, authorities have capped the number of cars that can be sold in a year, banned diesel cars, introduced Euro V emission standards, phased out more than 600,000 old vehicles, restricted the movement of more than 150,000 old and polluting vehicles by insisting they stick an identifiable yellow label and slapped high and variable parking charges to control PM 2.5 emissions.