From Katy Kiernan
In response to work by Joshua Mott and colleagues on a decline in suicides following the adoption of catalytic converters (7 September, p 24), Graham Jones suggests that potential suicide victims will switch to other methods (5 October, p 28).
A study by Tim Amos, Louis Appleby and myself (Psychological Medicine, vol 31, p 935) examined the changes in suicides by different methods in England and Wales from 1987 to 1998. We found that there was a decrease in suicide by car exhaust asphyxiation which was most marked after 1993 – the year the relevant legislation came into force. However, there was a simultaneous increase in suicide by hanging over the same time period. This seems to be an example of method substitution as described by Graham Jones.
Brighouse, West Yorkshire, UK
