Well,
I use a 3M half-mask with ABEKP3 multiple filter (Those codes are used in Europe, I don´t know if those codes are the same in North America... I think yes...).
A & B stands for organic compounds...
E stands for acid vapors (99,99999% probably you will never need this quality)
K stands for ammonia compounds (liquid masks usually have some ammonia, but this is a marginal question)
P3 is the degree of retention capacity of solid airborne particles.
This shoul be enough, really enough.
The weak point of filters is that they are not fully efficient retaining alcohol-vapors when their airborne concentration is really high. But for modelling environments, they work perfectly.
But the best protection comes from working in a well ventilated area, or working with a painting hood.
Cheers
RG