"Stranger suicide" and "detergent suicide"

A number of years ago I gave a series of lectures on toxic gases (asphyxiants, irritants, war gases), and during the irritant gas lecture I always made a point of emphasizing that hazardous gases could be inadvertently created in the home or workplace by inappropriately mixing household cleaners (an acidic liquid + sodium hypochlorite bleach, or the latter plus ammonia).  Now I see reports that such mixes are being used intentionally during suicide attempts.

The Telegraph this week reported on a case of "stranger suicide" -

A man and a woman have been found gassed to death with toxic chemical in a car on a rural road... Their Ford Ka had been sealed from the inside and marked with a handwritten sign indicating that it contained hazardous materials... A senior source told the Sun newspaper: “There is no obvious link between them."

About six months ago I had bookmarked a similar case from The Guardian:

Police believe a couple found dead in a suspected chemical suicide pact met only hours before and had made contact via the internet... The bodies were found in the fume-filled car, which had notes placed on the windows warning of the toxic chemicals inside. The Sun said Lee, who reportedly had a severe eating disorder, had used the [internet] forum to ask advice on concocting a toxic mix to take her own life.

The most detailed explanation of the phenomenon was at Wired two years ago:

A suicide technique that mixes household chemicals to produce a deadly hydrogen sulfide gas became a grisly fad in Japan last year. Now it’s slowly seeping into the United States over the internet, according to emergency workers, who are alarmed at the potential for innocent causalities.

At least 500 Japanese men, women and children took their lives in the first half of 2008 by following instructions posted on Japanese websites, which describe how to mix bath sulfur with toilet bowl cleaner to create a poisonous gas. One site includes an application to calculate the correct portions of each ingredient based on room volume, along with a PDF download of a ready-made warning sign to alert neighbors and emergency workers to the deadly hazard...

The American version of the method substitutes a common insecticide for the bath sulfur used in the Japanese recipe; bath sulfur isn’t available in the United States...