From 2007 all new diesel cars, minibuses and vans in Switzerland could be fitted with special filters to help curb dust particle emissions.
The government on Friday presented a package of measures aimed at reducing diesel emissions. A final decision is expected at a later date.
The latest package of anti-pollution measures is the second phase of the government's overall programme to reduce levels of diesel emissions and soot launched by the environment ministry in January.
Many urban centres regularly suffer above-average fine particle levels and persistent winter smog. According to the environment agency, approximately 3,500 tons of diesel soot were emitted in 2005.
Fine particle air pollution is one of the greatest problems facing the environment and people's health. Experts say dust particles cause 3,700 premature deaths in Switzerland a year and annual extra health costs of SFr4.2 billion ($3.4 billion).
Particles found in the air, which are natural or man-made and include soot, heavy metals and sulphates, are said to cause respiratory problems and could lead to lung cancer.
In addition to the fitting of filters to all new diesel vehicles under 3.5 tons, new diesel tractors would require filters from 2009.
The Swiss authorities said they have notified the World Trade Organization (WTO), the European Union and the European Free Trade Association (Efta) of this decision, which complies ahead of time with the European standard on diesel emissions for light vehicles.
The government added that it was waiting for a response from these organisations before it makes a final decision.
Under the five-point action plan agreed on Friday, the government wants to offer tax breaks to public transport companies which equip their vehicles with the appropriate filters in an effort to reduce emissions.
As of next year diesel vehicles purchased by the government for administrative or military purposes would also have to be properly adapted.
Heavy goods tax
Ahead of the government's plans to raise the heavy-goods road tax in 2008, which is expected to bring in over SFr1.33 billion, the authorities intend to start negotiations with the EU over possible reductions to a road tax levied against trucks equipped with anti-particle filters.
Brussels agreed to allow Switzerland to include this road tax in a bilateral agreement on transport, in exchange for the Swiss allowing heavier trucks (from 34 to 40 ton) to transit the country.
The Touring Club of Switzerland welcomed the government plan but said it was sceptical about a positive response from the EU and the WTO.
The Road Haulage Association said it was pleased that the government stopped short of calling for all old diesel vehicles to be re-fitted with filters.
Environmental groups and trade unions criticised the planned measures as not going far enough.
The cantonal authorities, which are responsible for implementing environmental measures, said the plan had their backing and would help combat fine dust emissions efficiently.
swissinfo with agencies
Three million people in Switzerland – more than 40% of the population – live in regions that record above-average fine particle levels.
Permitted level of fine dust particles - Switzerland: 50 micrograms per cubic metre; EU: 50 mcg/m3; US: 150 mcg/m3.
Dust particles cause 3,700 premature deaths a year in Switzerland and annual extra health costs of SFr4.2 billion ($3.4 billion).
The Swiss environment agency says 21,000 tons of fine dust is emitted in Switzerland every year.
56% comes from the private and public use of mechanical abrasion.
The rest comes from diesel motors (17%), wood burning (15%), other burning (10%) and petrol, natural gas and natural oil (2%).
In compliance with the JTI standards