Emissions from exhausts can be limited with ceramic filters that remove the particulates.
See how the filters work.
The graph shows levels of particulates in different parts of the UK.
Click for a text description of the graph.
Not surprisingly, city centres show the highest levels of PM10's. London is particularly high. One estimate says that nearly 80% of the PM10's in London come from traffic exhausts.
A level of 50 microgrammes has been set as a safe maximum, but long term exposure to lower levels could damage health.
The UK Government categorises air quality on a scale of 1-10.
Unlikely that any effects will be noticed. Possible risks from long term exposure.
Sensitive individuals may notice mild effects. Asthma sufferers may have more attacks. Elderly and those suffering from lung diseases show shortness of breath.
More significant effects on sensitive people. Elderly and asthmatics should reduce time spent outdoors.
Worsening effects on sensitive people. Prolonged exposure may result in hospitalisation.
Should cars and lorries be banned from city centres? Would people use public transport or just use their cars to go to shopping centres out of town?