Hugs of sympathy to Frenchie333 for what you have gone through with MCAS. Found out about it just now in my favorite place: Google.
You probably looked there also, to learn what can trigger it.

Regarding hair color; I learned blonds really do have more fun when I chose to change from rodent brown: age 19-24. It became sort of platinum blond, until the quality was stripped out. Back to my natural blah. Sixty years later most of that color has faded to the direction of gray. Now it really is effortlessly platinum blond.

Regarding chemicals, with WuFlu, one can get it through the eyes. Reading that led me to stop eye makeup for fear I might rub my eyes. So much for past glamor. I’m too practical, and more than that frightened of catching covid. Today I had Moderna #5, the third booster which is considered bivalent against omicron. A week ago senior dose quadrivalent flu shot. The timing of those came from my pcp. Preparing like a Girl Scout. No substitute for preparedness.

Now to make my favorite dinner. A big green salad tossed with blueberries salmon, etc; and pulverized organic tangerine peel, olive oil crushed with Meyer lemons, aged balsamic dressing. Wishing everyone well.