my mom has a perfume allergy. and many more things than you would think can cause her to get the sniffles, or (if applied topically) cause her skin to break out in a rash. i personally don't like the smell of perfumes, because we weren't exposed to them growing up. sometimes it can be hard to avoid perfumes, especially if the people providing us services feel like drenching themselves in the stuff.
enter Looney Labs. Kristen Looney (iirc) also has an allergy to perfumes, to the point where they can give her migraines. to avoid hurting people's feelings too badly, they developed these cards, to be handed out when standing and explaining the problem would just exacerbate it. i got my mom a set of these, and she found yet another use for them.
at bloodmobile last week (which is at our church, so we fill volunteer positions), she affixed the card to her name tag, since we already noticed one of the collection staff was going to be a problem. it worked!
(oh, and that's her 11 gallon pin... i'm only six donations behind her!)
23 hours ago