Since 1 Jan 2001, all petrol- and diesel-driven vehicles are required to comply with the Euro II exhaust emission standard as specified in the European Directive 96/69/EC for passenger cars and light duty vehicles with maximum laden weight (MLW) of 3,500 kg or less, and 91/542/EEC Stage II for heavy vehicles with MLW of more than 3,500 kg before they are allowed to be registered for use in Singapore. To comply with the emission standards, all petrol-driven vehicles are equipped with 3-way catalytic converters.

Further to the above, all new diesel-driven vehicles from 1 October 2006 onwards must comply with the Euro IV exhaust emission standard as specified in the EC Directive 98/69/EC-B(2005) for passenger cars and light duty vehicles with maximum laden weight (MLW) of 3,500 kg or less and EC Directive 1999/96/EC-B1(2005) for heavy vehicles with MLW of more than 3,500 kg before these vehicles can be registered for use in Singapore.

Motorcycles/scooters registered between 1 October 1991 and 30 Jun 2003 were required to comply with the US 40 CFR 86.410-80 Emission Standard. With effect from 1 Jul 2003, all motorcycles/scooters must comply with the exhaust emission standard as specified in the European Directive 97/24/EC before they can be registered for use in Singapore.

With effect from 1 Aug 2000, all off-road diesel engines are required to comply with either Japan, US or EU off-road diesel exhaust emission standards. Any equipment or machinery that is equipped with diesel engines as the main or auxillary prime mover and not registered with the LTA for use on public roads requires to have a permit prior to the import of such equipment. The application form is to be submitted to PCD one month prior to the import of the equipment. The form is available for downloading under the downloadable forms page in this website.

In addition, all vehicles are subject to mandatory inspections periodically. During such inspections, emission of the vehicles is tested to ensure that they comply with the prescribed standard.

NEA takes stringent enforcement actions against smoky vehicles on the roads. Regulation 19 of the Environmental Protection and Management (Vehicular Emissions) Regulations stipulates that it is an offence for any person to use or permit the use of any smoky vehicle on the road.

It is the responsibility of every owner of a vehicle to ensure that the vehicle is in good condition before using it on the road. Besides carrying out proper servicing and maintenance of the vehicle regularly, the driver must also not overload the vehicle or drag the engine of vehicle while driving. For 2-stroke motorcycles, the cause of white smoke emission is usually due to addition of lubricating oil in excess of the amount specified in the vehicle manufacturer's manual.