A.,
No, I don't think they should wear perfume, I know some women, especially my own mother, doesn't hardly go anywhere without spraying herself down. I wear it on special occasions. I think you should address the issue again this time with the teacher herself. Maybe she just doesn't realize how much she is putting on, I know my mom says she doesn't think it's that strong, but you can tell she's been through a room. You already went to the director, this time just go straight to the teacher, if I was the teacher, I would much rather have the mother come directly to me instead of feeling like she was going behind my back, I would feel like I was being attacked. I worked with this woman who lived with CATS, like 10+, this was in southern Texas, she couldn't afford AC and in the summer time she smelled really bad. She dressed very professional, her cats were her life. However, she smelled very bad. Other people would talk very bad about her, especially our boss. She was a very nice lady and I would have to tell her how bad she smelled, that was hard, but I know she appreciated me for being honest with her. She didn't think she smelled, she even told me she just bought the outfit. So if I was you, talk to the teacher, let her know how concerned you are about your son and his allergies. If she's with him all day, I'm sure she'll notice how better he gets when she doesn't wear the perfume.
God Bless