Deliberate Exposure to Motor Vehicle Exhaust Gas: The Psychosocial Profile of Attempted Suicide

Abstract

Objective: Deliberate exposure to motor vehicle exhaust gas has become the second most commonly used method of suicide in Australia. In an attempt to understand the factors contributing to the rise in popularity of this method, the psychosocial profiles, factors influencing method choice and circumstances of the act of self-harm were examined in a group of survivors.

Method: A cross-sectional cohort study of 30 patients presenting for hyperbaric oxygen treatment having survived deliberate exposure to car exhaust gas was undertaken. A structured clinical interview was administered together with scales measuring depression, hopelessness and suicidal intent. Daily assessment of mental state and cognitive function was performed.

Results: Factors common to the majority of subjects included male gender, age group of 20–50 years, and alcohol abuse. Relationship discord was the most common precipitating factor. Reasons given for choice of this method included the availability and accessibility of motor vehicles, painlessness, awareness that the method was lethal, knowledge of another person's successful suicide by this method and awareness of the method through media portrayal. Most of the cars used did not have engines fitted with catalytic converters, substantially increasing the risk of toxicity. Regret of the attempt, denial of further suicidal ideation after the event, and the absence of a suicide note were common findings. Most denied excessive time spent planning. The most common diagnosis in this group was adjustment disorder with depressed mood. Suicide intent scores were not high, inconsistent with the majority of patients being aware of the lethality of the method.

Conclusion: Sociodemographic findings resemble those of psychological autopsy studies of subjects completing suicide by this method. Survival in this group was due to failure of the method or unexpected discovery rather than patient factors. This population described the method as highly acceptable and accessible emphasising the urgent need for reduction of access to this means of suicide in Australia.