What Governs Lethality?
A number of factors are theorized to influence the lethality of a given method. The first is inherent deadliness. For example, car exhaust with a high CO level will be more deadly than car exhaust with a low CO level. The second is ease of use. A method that requires technical knowledge is less accessible than one that does not. The third is accessibility. Given the brief duration of some suicidal crises, a lethal dose of pills in the nightstand poses a greater danger than a prescription that must be hoarded over months to accumulate a lethal dose. Similarly, a gun in the closet poses a greater risk than a very high bridge five miles away, even if both methods have equal lethality if used. The fourth is ability to abort mid-attempt. More people start an attempt and abort it than carry it through; therefore, methods that can be interrupted without harm mid-attempt — such as overdose, cutting, CO poisoning, and hanging/suffocation — offer a window of opportunity for rescue or change of heart that guns and jumps do not. The fifth factor is acceptability to the attempter. Although fire, for example, is universally accessible, it is rarely used in the U.S. for suicide.