Metol allergies usually cause rashes and itching, from my haz waste days I know ammonia causes irritation of the mucous membranes (your throat has them). I am willing to bet your problem is lack of ventilation. Ammonia gases can accumulate and cause this reaction. I have had it, just not in the DR. Until you get your ventilation, I would suggest you cover your fixer tray, this should take care of it.