Just unwrapped a couple of those Harpic under the rim fizzer block thingies. The first one was a bit crumbled, so I opened the little bag very carefully. Some powdery dust puffed up out of it. I think my mouth was fully closed - I can't remember.
I have a sore(ish) throat now. I am a worrier. I don't feel I actually breathed it in as such, but do you know what I mean?
Probably just being silly. I rarely use heavy duty cleaners and I think this is a lesson to me to go with less toxic stuff.