Just how unsafe is hardiboard to cut & nail? Reason I'm asking is because I just bought a new canister set for my AOS face mask and the instructions say it protects against organic vapors but not silica dust. Now I always thought a vapor was much finer than a dust, but I guess not. I'm planning on replacing a bunch of masonite with hardiboard panels but now I'm not sure what type breathing protection I need when cutting the stuff.
Red