Suicide deaths by gas inhalation in Toronto: An observational study of emerging methods of suicide

Suicide death by gas inhalation has been the subject of global scientific interest due to a rapid increase in the use of helium and charcoal gas for suicide. These may be particularly amenable to means restriction strategies. There has been little scientific attention of this phenomenon in Canada.

A review of coroner records was conducted for all suicide deaths in Toronto (1998-2015). Deaths were categorized as due to inhalational asphyxia by compressed gas (i.e. helium or nitrogen), charcoal burning or motor vehicle exhaust, with suicide deaths by other methods as a comparator. Demographic, clinical and suicide specific differences between decedents in these four categories were compared using chi-squared or ANOVA global test of significance with additional pairwise comparisons where appropriate. Secular trends were also examined.

Gas inhalational deaths accounted for 190 (4.7%) of all suicides in Toronto (n = 4062) over the study period and a higher proportion of males used compressed gas or motor vehicle exhaust gases than those who died by other methods (83.3% and 84.0% vs.69.7%, both p = 0.01). Comparing 1998-2003 to 2010-2015 there was a 1075% increase in deaths by helium (4 vs. 43 deaths) and a 533% increase in deaths by charcoal burning (3 vs. 16 deaths) although helium and charcoal burning deaths still accounted for only 4.2% of total suicides 2010-2015. Deaths by helium were more likely to be accompanied by the book "Final Exit" than those by non-inhalational methods (15% vs. 0.7%, p < 0.0001) while 13 of 14 people who died by charcoal burning whose ethnicity could be determined were Asian.

Ethnicity and specific details of procurement of suicide methods were not systematically available in coroner records.

Suicide by inhalational asphyxia, particularly by compressed gases, has increased substantially over time in Toronto consistent with observations in other countries. Increased surveillance of these deaths, efforts to restrict access to these methods, and timely interventions including minimizing media reporting are all warranted.