Bharat Stage V (BS-V) and Bharat Stage VI (BS-VI) emission standards for two-wheelers, which were expected to be rolled out by 2022 and 2024 earlier, will be introduced from 2019 and 2022, respectively, the roads ministry said in draft guidelines issued on Saturday.

Environmentalists warned of the dangers of delaying immediate nationwide extension of BS-IV emissions standards, which are in force only in a few Indian cities.

The announcement came just two days before world leaders converge in Paris for a climate summit starting Monday

“The much-needed strategy to cut highly toxic emissions from diesel commercial fleet significantly and to nearly equalise petrol and diesel emissions by leapfrogging to Euro VI emissions standards by 2021 can be compromised if the current baseline emissions from all vehicles are not pushed up to Bharat Stage IV level nation-wide immediately,” Centre for Science and Environment (CSE), an environmental NGO, said in a statement.

CSE said trucks and other diesel vehicles are still languishing at Bharat Stage III nationwide, adding to local and regional pollution.

“Immediate extension of Bharat Stage IV emissions standards to all vehicles nationwide can reduce highly toxic and cancer-causing diesel particulate emissions by more than 80% and nitrogen oxide by 30% from the new fleet. This can also facilitate quick move towards Euro V and Euro VI within five years when particulate emissions can be brought down further by 66% and nitrogen oxide by yet another 80%,” the CSE statement added.

Various studies in past several months have labelled Delhi as the world’s most polluted city. A dozen other Indian cities are in the list of top 20 most polluted cities across the world.

The emission norms for two and three-wheeler categories will be notified shortly with advanced timelines similar to the four-wheeler category.

The road ministry statement said it is keen that the road transport sector take a lead role in reducing the harmful effects of emissions on environment and climate change. “This reflects a firm commitment to play a major role in reducing vehicular emissions,” the statement said.

At present, government is looking at adopting BS-IV emission norms nationwide by 1 April 2017.

Allowing BS III to languish till 2017 is regressive, “as the inertia in the system will resist and delay the industry preparedness and block the move to Euro VI by 2021” because the diesel industry is already opposing the quick move to tighter emissions standards, said the CSE statement.

“It is deplorable that the market for Bharat Stage IV compliant trucks and other highway commercial vehicles has remained a non-starter because of lack of uniform emissions standards in the country. Industry is still selling grossly polluting diesel technology,” said Anumita Roychowdhury, head of CSE’s air pollution team.

Damandeep Singh, director at Carbon Disclosure Project (CDP) India, welcomed the move.

“It is a welcome move by government but I think the government probably need to push industry a little harder. Industry though, is ready, as they already have a separate supply line for their vehicles that they export to countries (like to Europe) who have tighter emission norms. The question about why they are not doing in India could be about fuel quality issue. So basically, all that is needed is a definite push from government,” Singh said.

CDP India is an international not-for-profit organization providing global systems for companies and cities to measure, disclose, manage and share vital environmental information.