Sore throat from propane fumes?

I work in a factory that produces plastic car bumpers, and on many of the products we produce, we have to use propane torches to flame the excess plastic on the parts. Every shift that I work on a part that requires flaming with a propane torch, the back of my throat swells and gets sore, and I have a lot of trouble swallowing, and a little trouble breathing if it gets bad. The torches are supposedly made to eliminate propane fumes while burning, but I don't understand why I'm having these problems. Could it be from fumes from the burning plastic? Or maybe just inhaling the hot gas? I don't know. I'm lost, I really don't know what to do. I'm afraid that if they determine that I can't work around these torches, that I'll lose my job and won't be able to take care of my family. What should I do?