There have been suggestions that nitrogen could be used as a means of execution: https://www.telegraph.co.uk/news/worldnews/northamerica/usa/11495658/Michael-P

There have been suggestions that nitrogen could be used as a means of execution: https://www.telegraph.co.uk/news/worldnews/northamerica/usa/11495658/Michael-Portillo-inspires-Oklahoma-to-consider-execution-by-nitrogen.html https://www.telegraph.co.uk/news/worldnews/northamerica/usa/... [NB Personally, I'm not in favour of executing anyone, but if you must do it why not do it so that it doesn't cause any suffering?]