Carbon fiber is very bad stuff. You seriously don't want to breathe the dust when you sand it.

I wore gloves and a fiberglass respirator (3M #N95). I cut the spars using a hack saw and then sanded the ends on my larger disk sander with a vacuum attached (wearing protection throughout the entire process).

When I was finished I put the tube in the vacuum hose to suck out stuff inside but that wasn't enough so I went outside and used high pressure from my air compressor to blow through the tubes. Carbon fiber scares me a lot more than the cigarettes I smoke.