I don't know anything about
the negative ion stuff, but I've read that Far Infrared saunas is one of the most effective ways to detox. Although, you do want to be careful to stay very well hydrated and to very slowly build up your time in one.
You might find this very recent thread on the subject helpful:
www.healingwell.com/community/default.aspx?f=30&m=3521396And here is another one from a bit earlier this year:
www.healingwell.com/community/default.aspx?f=30&m=3467475&p=1