I found this paper online and thought I should post a link. It's a great read especially if you're thinking of going deep on air:

http://www.oseh.umich.edu/diving%20articles/abolish.pdf

So what's your personal dept limit on air? I just did my deepest dive on air a few days ago down to 141 FSW and felt comfortable and kept well within my no-deco limits on my computer.