A SAFETY limit for benzene, a cancer-causing air pollutant, has been recommended for the first time by a government panel. The main source of the chemical is car exhausts and petrol fumes, writes Nicholas Schoon.

The government-appointed Expert Panel on Air Quality Standards yesterday recommended an annual average concentration of five parts per billion in air. This limit is already approached or exceeded in some urban areas with continuous heavy traffic.

The panel also recommended that this limit should be reduced to one part per billion and that the Government should set a target date by which this should be achieved. Ministers promised to consider the recommendations 'very carefully'.

Studies on animals and on people exposed to high benzene levels at work have shown the chemical can cause some types of leukaemia by damaging genes. Cigarette smoke is also an important source of benzene for smokers. The spread of catalytic converters, now compulsory on all new cars, should lower benzene levels. The European Commission has also proposed legislation for reducing emissions, by making mandatory the fitting of benzene-absorbing devices at petrol stations or next to the fuel tanks of cars.

Petrol companies say the devices should go on the cars, while the car manufacturers have claimed that the controls are needed at the petrol pump. The argument has been running for years, but it now looks as if the car manufacturers are winning.