Have you talked to the pulmonologists there. They should have some insite on the situation. It does sound like your exposure to methacoline is triggering an attack and you need regular treatment for that. Also, what caregiver222 said about protective breathing aparatus would be a good policy to adopt. I hope you get some help and answers soon.
You might try a positive pressure face mask, which is easy to cobble up.
You need a compressor. Fortunately, the plug-in electric compressors for patients that administer albuterol are perfect.
Next you need a LONG length of tubing. Long enough to draw fresh air from somewhere.
In a best case the compressor would be outside.
Next you need a mask that will admit outside air. You might try an ordinary non-rebreather.
And, of course good air exchanges inside the treatment room.
A positive pressure mask insures that you do not breath in air from close-by.
You may well have asthma and need tighter fitting mask or even relief from exposure to methacholine