the state refiners ability to invest in upgrading old plants or build new units to produce cleaner fuels they invested over rs 30000crore in new technology to make bsiii and iv fuels the green tax on vehicles wouldnt improve their ability to invest since the money would go to the government lax enforcement of vehicle fitness rules is a major contributor to vehicular pollution trucks cars autos and twowheelers spewing smoke is a common sight many are more than 1520 years old theres hardly any annual check on their fitness pollution under control certificates are not above suspicion as far as delhincrs case is concerned there appears to be a tendency to overlook the three coalfired power plants in and around the city and illegal industrial units dotting delhis periphery the problem gets compounded by the dust kicked up by the construction boom all over the city without the safeguards and dust shields prescribed in the law unless all these are tackled together merely taxing diesel vehicles would fail to clear the air either in delhi or elsewhere in the country reform roadmap 1991 petrol standards issued unleaded petrol catalytic converter introduced 1992 diesel standard introduced 1999 supreme court orders euro norms implementation 2002 mashelkar panel report turned into national auto fuels policy bharat stage iv norms are in force in 20 cities by 2015 these emission norms will be extended to 50 more cities