here is an interesting article by jay wiseman.

http://epedominion.net/HealthSafty/breath.htm

i love breath play however i know the risks involved and take my own responsibility for that, somebody mentioned they dont mind passing out?
im sorry if i appear rude but as well as being a bit on the dangerous side and none too pleasent doesnt it kind of defeat the object?
im assuming you dont have intercourse while you're unconcious or feeling headachy, hot and nauseous afterwards!