Noting that cars emit more Particulate Matter (PM) 2.5 than several other key pollution sources in Delhi, Centre for Science and Environment (CSE) condemned the "motivated" campaign and said the auto industry is also underplaying the toxic and cancercausing effects of diesel emissions.

CSE said estimates of International Council on Clean Transportation say that cancer risk from diesel vehicles in Delhi is four times higher than petrol cars.

Observing that new action taken by government to curb air pollution has started giving results and it cannot be "derailed", the green body said the city has to step up action on all key sources of pollution, including vehicles, to meet clean air target throughout the year.

"CSE condemns the misleading number game and motivated campaign of the auto industry to claim that vehicles in Delhi are an insignificant source of pollution. It is ironical that now 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. While action on all key sources should be stepped up, vehicles including diesel vehicles will require stringent action as they emit the deadliest toxins within our breathing zone," CSE said.

Noting that the auto industry is underplaying the toxic and cancer effects of diesel emissions, CSE Director General SunitaNarain said an IIT Kanpur study has established diesel cars on an average contribute 78 per cent of PM 2.5 from four wheelers.

"This is significantly higher than the contribution of petrol and CNG cars. Cancer effect occurs at very small doses. According to California Air Resources Board the number of excess cancer cases per million people due to lifetime exposure to only 1 microgramme per cum of diesel particulate is 300 as against 29 for benzene that comes predominantly from petrol.

"The cancer potency of diesel particulate matter is 10 times more than benzene. Even after improving emission standards in California cancer risk from diesel particulate matter in Los Angeles is 68 per cent," CSE said.

CSE said estimates of International Council on Clean

Transportation on cancer risk from diesel vehicles in Delhi are four times higher than petrol cars.

"More than 2,80,000 avoidable cancer deaths in Delhi are being attributed to diesel exhausts. Particulate emissions from diesel and coal combustion are more harmful than others," she said.

She said cars emit more PM 2.5 than several other key pollution sources in Delhi while they also emit more Nitrogen oxides (NOx), which are are a family of poisonous, highly reactive gases, than several other key pollution sources in Delhi.

CSE said vehicles at 36 per cent are the second largest contributor to NOx and only cars emit 6.1 per cent of the total NOx from all sources.

"This is equal to the third largest contributor of NOx which is diesel generator sets at 6 per cent. The rest including domestic sources (2 per cent), industrial areas (1 per cent), hotels and resturaunts (less than 1 per cent) and others emit significantly less than cars. This clearly brings out that Delhi cannot meet its clean air objective if stringent action is not taken on cars," CSE said.

CSE also said the industry has not accounted for the vehicles contributing to secondary particulates (formed from the gases - NOX and SO2) that are quarter of PM2.5 in Delhi's air. CSE said if contribution of vehicles to the secondary particle is accounted for the contribution of vehicles to PM 2.5 will be much higher.

"Kanpur IIT study states that vehicles are the most consistent source of pollution throughout the year while most others are variable - control on consistent sources are important to achieve cleaner air 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 is an important signal. This needs to be encouraged and not blocked with misinformation. Support action and not inaction," Narain said.

Noting that rising diesel car numbers are "negating" the benefits of moving public transport and light commercial vehicles to CNG, CSE said one diesel car emits particulate matter equivalent to 5 petrol cars, nine diesel cars emits equal to one diesel truck and six diesel cars emit equal to one diesel bus.

"This in other words mean that the total number of diesel cars which is 68,384 diesel cars that got registered in Delhi in 2014-15 has virtually brought back more than 3.4 lakh petrol cars or about 7,598 trucks or about 11,397 diesel buses to pollute the air of Delhi," CSE said.

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CSE said that although the industry claims that petrol and

diesel cars are equally to be blamed, they, however, omit to mention that emissions related to petrol cars have declined despite the increase in their numbers.

"Industry claims that petrol cars emit more carbon monoxide than diesel cars and, therefore, diesel cars cannot be treated differently. But official data clearly shows that carbon monoxide emissions have reduced despite the increase in petrol car numbers.

"The trends have decoupled. But increase in diesel car numbers are correlated with rising NOx and PM emissions, as diesel cars are legally allowed to emit three times more NOx and several times more particulate matter than petrol cars," CSE said.

It noted that other governments with similar contribution of pollution from vehicles are taking "significantly and stronger" action on vehicles than Delhi.

In Beijing, vehicles contribute 30 per cent of PM2.5, close to what it is in Delhi, CSE said.

To address it, Beijing has capped the number of cars that can be sold in a year, banned diesel cars, introduced Euro-V emissions standards, phased out more than 6 lakh old vehicles, restricted movement of more than 1.5 lakh old and polluting vehicles by labelling them yellow and slapped high and variable parking charges.

"There is barely any action on the cars in Delhi. This demonstrates how even with the current share of vehicular pollution, Delhi will need much more stringent action along with action in all other sectors," CSE said.

It said that the industry is silent about mass failure of diesel car models in meeting real world emissions limits in Europe and the US and worsening air quality.

"Hard selling diesel cars industry is silent on the new emissions results from Europe and the US on diesel cars. Even after meeting Euro V and Euro VI emissions standards NOx pollution is increasing in European cities. The United Kingdom was dragged to the Court for violating NOx standards.

"Spate of emissions testing results have come from the British, German and French authorities over the past few weeks that show how large number of popular diesel car models have failed to meet the official limit and are emitting 6 to 12 times higher than the real world. This has led several governments to come up with policies to restrict diesel cars and further tighten the emissions regulations," CSE said.