TUESDAY, Aug. 27, 2002 (HealthDayNews) -- Catalytic converters, designed to reduce automobile emissions, may be doing more than help keep the air clean -- they may also be saving lives.
A new study, appearing in tomorrow's issue of the Journal of the American Medical Association, found that the death rate from unintentional carbon monoxide (CO) poisoning in vehicles has fallen 81.3 percent since the advent of the catalytic converter. And because most CO poisoning deaths are vehicle-related, the converters are also responsible for a 57.8 overall drop in the CO poisoning mortality rate, the study says.
Since the introduction of the catalytic converter, an addition to a vehicle's exhaust system that reduces CO emissions and other pollutants, there also has been a 43 percent cut in suicides committed by intentional CO poisoning, the study says.
"The data clearly show the catalytic converter was associated with reduced deaths," says one of the study's authors, Joshua Mott, an epidemiologist in the air pollution and respiratory health branch of the Centers for Disease Control and Prevention. In fact, he adds, "11,700 deaths may have been prevented by the introduction of the catalytic converter."
Catalytic converters were introduced in the mid-1970s, enabling car manufacturers to comply with the Clean Air Act of 1970.
Approximately 2,000 people die from carbon monoxide poisoning every year, according to the study. One common source of carbon monoxide is automobiles, particularly when they're operating in enclosed or semi-enclosed areas, like a garage. Seven out of 10 carbon monoxide poisoning deaths are vehicle-related. A high enough concentration of CO can cause unconsciousness and death in just a few minutes.
Mott and his colleagues gathered death certificate information from 1968 through 1998 to see how many deaths were attributable to CO poisoning. From 1968 through 1978, the death rate remained fairly steady. But, after car manufacturers started installing catalytic converters, the death rate from unintentional CO poisonings dropped dramatically.
Carbon monoxide detectors were introduced around 1992, but Mott says there was no dramatic decline in unintentional deaths from CO around this time.
"Only following the introduction of the catalytic converter did we see declines in the death rate," Mott says.
"The authors make a pretty good argument [that the drop is related to catalytic converters]," confirms Dr. Harvey Himel, director of wound care and hyperbaric medicine at Weill Cornell Medical Center of New York-Presbyterian Hospital in New York City.
Interestingly, the number of motor vehicle-related carbon monoxide suicides also went down during that same period. Mott says the researchers can't speculate why this is so.
Despite the decline in carbon monoxide deaths, Mott points out that "CO poisoning still remains a leading cause of unintentional death."
Symptoms of CO poisoning include headache, weakness, dizziness, and nausea or vomiting, says Himel. Eventually, continued exposure to carbon monoxide causes loss of consciousness and ultimately death.
Mott says an important way to prevent CO poisoning is to make sure home heating appliances are operating properly, and to not use kerosene heaters, charcoal grills, or power generators in enclosed areas.
Himel adds that carbon monoxide detectors are important as well. "You need a way to detect it. Carbon monoxide is odorless, colorless, tasteless, and non-irritating," he explains.
What To Do
For more information on this silent killer, go to the Consumer Product Safety Commission. And, here's a checklist from the Centers for Disease Control and Prevention on preventing carbon monoxide poisoning.
