I thought I had become allergic to balsa dust after 50 odd years of whittling the stuff into flying critters.
Sneezing, runny nose, bunged up ade"dddoids" and all that kind of thing.
IT IS IN FACT DOWN TO CYNO!:
My missus has now declared it a banned substance (so I hide it, and only use it on hinges, even then OUTSIDE the workshop!)
If I get a tiny wiff of cyno, flue like symptoms come on within an hour or so. It pays to read the warnings on these products!