One thing to help prevent becoming overly sensitized to any wood is to always wear some type of disposable or washable overall, like painters wear, you can get quite light ones for the summer time and heavier ones for when it is colder. You should look for elastic cuffs you can pull over your gloves.
Basically as nerdy as it seems you need full coverage, even your face, heck especially your face and eyes covered, this is very important never disregard eye protection, sealed eye protection for sanding, not standard safety shades. They make all this stuff, any safety supply shop should be able to set you up. its used everyday by woodworkers all over the world who cannot afford or who dont want to lose their livelihood.
If your arms are getting covered in sawdust, your getting sawdust on your face and in your hair, your just playing with fire, you may not be sensitized yet, and truthfully, maybe you never will, but if you do !!!
If you are covering up proper, then when your done your sanding sessions you must go outside, or into a 'dirty room' to take of the overalls first, dust off with a decent duster, wearing your respirator the whole time, it does not come off till your not all dusty. Never hurts to go wash up.
I know there are tons of stories about people who have worked with this stuff their whole lives in T shirts and shorts, getting covered in dust everyday, they are lucky I guess, becoming sensitized to wood, or whatever, is a personal thing, everyone is different, it doesn't mean you are not tough, it means your chemical make up really disagrees with whatever it is your getting exposed too, some people are hardly sensitive to wood, some not at all, some terribly so. There is no one size fits all prescription either, but a little prevention, that is proven to work. can never hurt. May be damn uncomfortable in the hot summer, but that's just the way it is.
Stay Safe everyone.
PS: on a related note, last summer me and a partner were removing a dead and crusty old Japanese Elm(IIRC ??), we had to buck the tree into firewood lengths once we dropped it on the ground, after cutting it up, my partner had to go to emergency ward for allergic reaction. I wore a bandanna as a makeshift respirator as I do some days if the wood is really dry and dusty, I told him to do the same but what do I know?
You see usually sawdust is quite wet, but occasionally a tree will be near dead and dried right out and when you buck them up they kick out big clouds of dry dust, much like sanding would(wood).
Thankfully it was/is a very rare tree, this persons grandfather had planted it not something we run into very often if ever before.