The proposals would enable local councils for the first time to restrict traffic on health grounds and could include establishing car-free zones or even banning polluting vehicles altogether when fumes threaten to reach danger levels.
The proposals, being prepared in the Department of the Environment and still to be put to Transport ministers, will be published in an official consultation document in the spring. They reflect a growing belief in government that gases from exhausts are worsening the asthma which affects one in seven British children and kills more than 2,000 people a year.
Last October, an investigation by the Independent on Sunday and Friends of the Earth revealed that pollution by nitrogen dioxide, the exhaust gas linked with asthma, was twice as bad in British cities as the Government had admitted. Ministers now accept that the introduction of catalytic converters - anti-pollution devices fitted to all new cars - will provide only a temporary respite: fume levels will soon rise again as the number of cars increases.
They believe increasingly that the only way to tackle the pollution crisis is to limit traffic in towns. The consultation paper will encourage councils to use their traffic management powers to cut air pollution.
For the first time officials are thinking of encouraging councils to ban cars without catalytic converters from urban areas on days when pollution is likely to be high, as in Germany.
In a forthcoming article in the journal Clean Air, to be reported on Panorama tomorrow, civil servants from the Environment department and the Meteorological Office will raise the possibility of such bans.