Hiya,
Simply put, reactive catalysts in coating products, no matter what people may tell you, are not good for humans.
I worked for a automotive paint distributor for many years and as early as 1982 we were told to discourage use of "hardeners" in enamel paints unless the shop had a downdraft booth and a supplied air system. We were not allowed to sell them "over the counter" to retail customers no matter what they said.
In 1987 we were told by the manufacture that enamel catalyst sales were restricted to commercial customers that had been certified to have the proper equipment and training, no other sales were allowed unless the district manager had inspected the location and certified it.
This was also the same year that the base coat systems came on the scene in a big way and we were cautioned that these were even more toxic, so much so that we were instructed to install a supplied air system in the mixing room. (We had no catalysts there, just base stocks and tints. Up to this point we were using organic certified masks) We were also told to use vapor barrier suits, chemical gloves and install a separate negative pressure HEPA-VOC ventilation system for the mixing room.
There are many complications and symptoms associated with refinish coatings not just lung damage. Nerve, reproductive, immune systems are all at risk. In 1986 there was a report of NY firefighter repair shop workers that were turning up sterile, the common denominator was the Imron paint they were recoating the firetrucks with.
I have seen first hand severe reactions to paint products. One that comes to mind. A customer of mine that had all the proper equipment and training and was certified to paint all products including catalyzed polyurethane enamel, (Imron, about 5x more toxic than acrylic enamel with catalyst) one day was "too busy" to properly prep a car and did the job in the corner of the shop with just a charcoal respirator, later that day he collapsed. He was eventually diagnosed with acute "paint poisoning" and ordered to stay away from autobody shops. What happened was that over the years he had accumulated enough chemicals in his body that he hit that "one time too many" point and had to sell his business.
Read the MSDN sheets of any chemical you use. Don't take any of the information lightly, they are put out for your safety. Don't get caught up in the "It's only one time" mentality. Remember, all those cans of spray paint you have already used without a mask left their mark in you. Your "one time too many" may be closer than you think.
OK, that's my 2 cents,
Tom