3 September 2002: The introduction of the catalytic convertor to reduce polluting emissions from cars has also had a startling and positive effect on the number of deaths of US motorists from carbon monoxide poisoning.

In a study led by Joshua Mott of the Centre for Disease Control and Prevention in Atlanta, Georgia, researchers found that overall CO-related mortality declined from 20.2 deaths per 1m person-years to 8.8 deaths between 1968-1998.

Unintentional auto-related deaths declined to less than a quarter of the 1968 levels, and vehicle-related suicides halved over the period.

The researchers have estimated that if CO levels in exhaust gases had remained at pre-1975 levels, some 11,700 more unintentional motor vehicle-related CO deaths would have occurred by 1998.

Catalytic convertors were introduced on American cars in 1975 under the 1970 Clean Air Act and CO emissions from cars decreased by more than 76 percent over the following two decades.

Any similar research in Europe would likely show equivalent results, though the advent of the catalytic convertor over here came somewhat later.