Suicidal carbon monoxide poisoning has decreased with controls on automobile emissions.

BACKGROUND Highway vehicle CO emissions have decreased 85% since introduction of the catalytic converter in 1975. We sought to examine whether morbidity and mortality from intentional motor vehicle-related CO poisoning have also changed. METHODS Vehicle CO emissions data from 1970-2013 were obtained from the U.S. Environmental Protection Agency. U.S. Centers for Disease Control and Prevention data were used for the suicide crude death rate (CDR) from CO poisoning from 1999-2010. Data on non-fatal intentional CO poisonings treated at a regional hyperbaric treatment center from 1981-2013 were analyzed with regard to numbers treated and presenting carboxyhemoglobin (COHb) levels. RESULTS Since 1985, the CDR for suicidal motor vehicle-related CO poisoning has decreased in parallel with CO emissions (R2 = 0.985). Non-fatal motor vehicle-related intentional CO poisoning cases decreased 63% over 33 years (p = 0.0017). COHb levels decreased 35% in these patients (p < 0.0001). CONCLUSIONS There has been a decrease in both fatal and non-fatal intentional CO poisoning from motor vehicle exhaust since the 1980s. This correlates with reductions in vehicle CO emissions and is a likely result of the U.S. Clean Air Act of 1970 and the application of catalytic converters since 1975.