Along the same lines as PT Doc, the shop I use to work in has had white PVC for the last 26yrs. Should be noted, it was about 18yrs in the first location and 8yrs in the current, but no issues ever. Trust me, it sketched me out a bit, but it was one of those things I didn't have control over, and my boss had great insurance, so kind of meh. I was really careful about flying objects around the drops (on both sides of all the lifts, two above my bench, etc) for damn sure, I didn't want to cause a problem that wasn't already there itself.
I went with 1/2" schedule 10 black steel pipe for my personal shop. In retrospect, I may have gone with 3/4" for the first run from the compressor down to first bench (about 26ft) and then up and over the shop with 3/4" also, but I made the call to go all-1/2" initially as it would save complexity and parts could be re-used elsewhere. Cheap, pretty easy, HD cuts it as many times as you need. So far I only have 1 drop, as we have to move the lift, but we will have drops above the three work surfaces plus on both lift posts this spring/summer. Around that time I imagine a thread will be posted too lol.