A research finding in England and Wales was that the suicide rate has been falling since anti-pollution technology in modern cars has reduced the danger of exhaust poisoning. A study of suicides from 1960 to 1997 in England and Wales found that between 1990 and 1997, the rates for suicide by motor vehicle exhaust poisoning fell from 41 per 1 million to 16 per 1 million, a decrease of 61 percent. Overall, male suicides in the same period dropped from 120 per 1 million men to 103 per 1 million. This coincides with the legal requirement to fit all new cars with catalytic converters.