Bill wrote:

I sanded some particle board by hand and got a very bad reaction. I
assume it's the "dust". If I spend some time in Home Depot or
Mennards I end up with some shortness of breath. Ace Hardware,
Sears, Kmart, Harbor Freight---no problems. Knowing this, would you
still not blame the dust?

Certainly the dust is suspect. Visit an allergist to find the EXACT cause.
It may be you're allergic to the dried pigeon **** from birds that get
trapped in the large stores. Or maybe it's a nervous reaction to all the
goodies in sight.

You won't know for sure 'til you get tested.