I have only minor asthma so not sure if this would work for her.
Anyway, I bought myself a Sharp air purifier. It has a built-in
ionizer. There are tons of different settings and you can turn off the
ionizer if you wish. It is very expensive though. You can see them on
the Sharp website - they have one for different countries too
(websites).

I find that I can get through nights without using my inhaler now. I
still need to rip out the carpet and get rid of my mattresses. I have a
cat too, but wouldn't get rid of her, she's such good company. My
doctor told me the cat dander gets into everything anyway, so even if
you get rid of the pets, it won't solve the allergy problem. He just
said I was likely immune to her now, but not to get any more pets.

I'm going to a naturopathic doctor to see if she can help me further. I
get it covered under my extended benefits plan at work, so it won't
cost me anything. I have not found any vitamins or herbs to be of help
so far.

Sometimes if I have heartburn I feel I am having trouble breathing and
I take baking soda in water, and that makes me feel much better. But
that's only if I ate something that bothers me. I have a ton of
allergies.

I think even a small change would help out your sister. I'm still
making changes but it's costly, and a slow process.

~Melanie