I think a lot depends on the individual and how much tolerance they inherently have. The fact that you've been able to stay in the trade and thrive as a painter speaks to that. I've seen people that walk into a body shop front office, never having been directly exposed to some of the chemicals that are used in the shop and have a negative reaction. They have a hard time breathing, they get dizzy and just start feeling like crap and then there are some people that totally ignore anything to do with safety and not a problem. Sometimes it seems that people get worse and worse off the more they are exposed. I know of a body man today that over 15 years, became allergic to body filler dust. I found that strange but, he can't get anywhere near the dust today or his whole body breaks out in hives.
I've been painting for many years, just like you Jay and I've taken the chance where my thinking was, it's only a small piece, I don't need to wear a mask. I'm sure most painters have done at least that but, as I got older and saw the problems related to doing it constantly, I even wear a mask now when I'm mixing a color in my mixing room. I think we're both fortunate and I won't take a chance anymore, I'm not nearly as invincible as I was when I was younger...LOL