Changing trends in suicides using helium or nitrogen - A 15-year study.

A study was undertaken of autopsy cases of suicide where either helium or nitrogen gas had been used (taken from Forensic Science SA files, 2003-2017). 33 deaths involved helium (age range 19-94yrs, average 47yrs; M:F-2.7:1), compared to 23 cases of nitrogen inhalation (age range 29-93yrs, average 66yrs; M:F-2.3:1). The combined numbers of deaths due to both helium and nitrogen inhalation showed a steady increase (5: 2003-2007; 31: 2013-2017); however, while helium deaths plateaued (14: 2008-2012, 15: 2013-2017) nitrogen-related deaths increased 16-fold. Specifically, the percentage of cases due to nitrogen inhalation increased from 20 to 52%, compared to helium which fell from 80 to 48%. Continued observation of the study population is required with evaluation of other communities and larger populations to monitor this potential trend, and to determine whether nitrogen may be superseding helium as the gas of choice in plastic bag and other asphyxial suicides.