I don't think you are being unreasonable, and there have been a lot of great options share by the previous posts you may want to explore. I would post a sign outside the classroom saying it's a fragrance-free zone due to a health condition. Teachers have rights, too.....
One of the biggest day-to-day toxins we encounter are from fabric softeners. I can't be outside when the neighbor is drying laundry due to the bilge coming from the dryer vent, and they do laundry seemingly constantly.... Not only from the scents in them, but people with skin issues can't have them near their skin. My sister-in-law loves to hug everyone when we all get together, but she breaks out in a severe rash on the side of her face from what people wear on their skin and the toxins left on the clothing from fabric softener. Her doctor told her the fragrance-free varieties are even worse due to the chemicals they use to make them without a fragrance.