I'd argue that it would take a LOT of pressure to actually crush somebody with air, and therefore a LOT of exertion on your character's part. Probably too much exertion. However, dropping the air pressure or raising it might still be viable because, A) it's within the realm of your abilities, and B) could probably disorient another person, even if it's just a little. Which in itself can be useful in a high-pressure situation.