Motor emissions is one of the key factors contributing to air pollution in modern cities such as Singapore.

While I am heartened that the National Environment Agency is stepping up enforcement against smoky vehicles ("25 motorists caught in a day in NEA operation against smoky and idling vehicles"; ST Online, Nov 3), just enforcing emission standards is not sufficient in the long run.

Eventually, there needs to be a shift from the use of petrol and diesel vehicles to plug-in hybrid and electric vehicles.

These vehicles are rare in Singapore for various reasons.

First, there is a lack of charging stations for owners to charge their vehicles.

However, things look set for an improvement, with the Government announcing plans to set up more charging points next year.

Second, the cost of buying such vehicles are higher than that for petrol and diesel cars.

The Land Transport Authority provides rebates to owners of vehicles with little or no carbon emissions.

However, it includes power grid emissions in its evaluation of the vehicle's carbon footprint, as electricity in Singapore is mostly generated by gas-powered plants, essentially reducing the eligibility of some electric vehicles for rebates.

But by switching to clean energy like solar energy, there would be no need to include power grid emissions, which would mean more rebates given out and more people attracted to buy these vehicles.

In addition, incentives such as free parking and access to bus lanes could be given to further encourage buyers to switch to plug-in hybrid and electric vehicles that are less harmful to the environment.

Josias Pawa