Deaths from motor-vehicle-related unintentional Carbon Monoxide poisoning–Colorado, 1996, New Mexico, 1980-1995, and United States, 1979-1992.
Carbon Monoxide (CO) is a colorless, odorless, toxic gas that is a product of incomplete combustion. Motor vehicles, heaters, and appliances that use carbon-based fuels are the main sources of this poison. Most fatal unintentional CO poisonings associated with motor vehicles are preventable and can result from differing mechanisms of exposure: (1) operation of a motor vehicle with a damaged or malfunctioning exhaust system and an inadequately ventilated passenger compartment (2) operation of a motor vehicle in an enclosed space (e.g., a garage) with inadequate ventilation, and (3) use of auxiliary fuel-burning heaters inside a passenger compartment or in a camper. This report describes the investigation of deaths associated with multiple motor-vehicle-related CO poisonings in Colorado on November 3, 1996, summarizes a review of such deaths in New Mexico during 1980-1995, and presents geographic and seasonal patterns in national death rates for 1979-1992. These findings indicate that deaths from motor-vehicle-related unintentional CO poisonings increase during winter months and that death rates from CO poisoning in stationary motor vehicles are highest in states with colder average winter temperatures.
Carbon Monoxide and Suicide Involving Motor Vehicles:
The Problem:
Suicide in Australia, especially that of young males has attained an alarming rate in recent years, higher than that in the USA and most other countries. Moreover, the use of motor-vehicle exhaust gas for this purpose has assumed the most popular role in such suicides. The Australian Medical Association in cooperation with other governmental and industrial groups as well as various individuals in Australia are attempting to find ways of reducing this tragic loss of young life. It is felt that by limiting the availability of the lethal component Carbon Monoxide (CO) in motor vehicle exhaust gas, the rate of use of this method will decline, possibly saving several hundred lives per year. The use of this poison is often chosen because of availability, ease of use, and supposed painless induction. The role of the media in reporting deaths from CO poisoning and the use of CO by Dr. Jack Kevorkian in the USA are felt to be exacerbating factors.
Suggested Solutions:
Accelerate the rate of installation of effective catalytic converters on Australian motor vehicles, possibly by instigating a retro-fit prgram.
Require the sale or retro-installation of CO Detectors on all motor vehicles in Australia that would warn drivers/occupants of danger, and/or, immediately shut-down the engine and prevent restarting.
Place a distinctive odorant in petrol/gasoline that would give motor vehicle exhaust an unpleasant odor and thus discourage/warn potential suicide attempters. Design ignition systems that prevent motor vehicles from remaining in an “idle” mode for more than a short time.
Limitations of Suggested Solutions:
Catalytic converters are expensive, eventually wear-out, slow to come on-line in Australia due to long vehicle life, and retro-fitting would be difficult and place financial burdens on people least able to pay.
Also, current catalytic converters still permit exhaust gases to contain lethal CO concentrations. Finally, the fact that catalytic converters only become effective in reducing CO at elevated temperatures means that exhaust gases continue to contain supra-lethal concentrations of CO during the “warm-up” period.
CO Detectors that produce engine shut-down” would have to be carefully designed so as not to exacerbate traffic problems due to elevated ambient CO conc. This approach appears to be the best overall solution at present, and could provide some additional health benefits separate from the suicide issue.
Solutions involving odorants in motor vehicle fuel might cause public discomfort and complaints and undesirable environmental pollution.
Most motor vehicles need the capability to idle, eg. waiting for traffic or stop lights, taxis, and vehicles being repaired.
Other Considerations:
Other problems peculiar to the Australian motor vehicle market are as follows:
- Australia represents just 1% of the world motor vehicle market.
- Average age of Australian motor vehicles (8 x 106) is 12-14 years.
It was my charge in visiting Australia in early April, 1998, to recommend to the AMA and the Working Group on Motor Vehicle Exhaust Suicide, a CO concentration that might be set as the threshold at which engine shut-down might occur. The subsequent pages display a model of the gases contained in motor vehicle exhaust, and reveal a “unique signature” that might be used to quickly and unequivocally identify a suicide attempt apart from simple leakage of outside gases into the vehicle.