You aren't trying to satisfy [i]me[/i], so it doesn't really matter what I think. I can only make suggestions according to what I think Allen, HWWB, and Jazzy would find acceptable.

I just find killing people via crushing them by air pressure is implausible, given how air is a collection of free floating atoms. You're going to have to take a lot of air to condense it enough to crush someone. But I doubt that's possible, because a lot of gases will turn into a liquid by that time.