I used to spray professionally in my cabinet shop. Used many multi-part finishes and I used what I considered sufficient filtering, course also what was affordable for a small 3 man shop. I had an extraction system that could change the air in the whole shop in less than 2 minutes. Kinda powerful. I thought that I would be ok. I was wrong. I now have COPD and Pulmonary Fibrosis. I have a very hard time breathing when exerting myself or even walking.
You have to take care of yourself -- especially for the younguns. I would suggest that you look at and externally supplied breathing apparatus. They are much more affordable now and they certainly will cost less than a Concentrator, hoses, canula's and Spiriva. Ask me, I know.User Friendly Supplied-Air Respirators: Options for Automotive Refinishers
Sherwin-Williams has a nice setup for about $150.00. I will no longer finish even with nitro-celluloids without and externally supplied air system. I also use tyvek suits when finishing now. Just can't risk it anymore.
Consider going with one of the options for safe spraying. I don't want another friend to go through what l have ahead of me. It is really debilitating.