Dear cdehrlic,
my name is Marco Stoller, assistant professor at the University of Rome "La Sapienza", Department of Chemical Engineering. I'm very courious about your call, since in my opinion it is difficult to forumalte colored smoke without dye and/or chemical additions which are normally non toxic but also not healthy. The only smoke this is accepted to be without harm is nowadays white, the same used in disco and e-cigarettes. It is possible to color this smoke by colored light sources, but this applys only if the light beam is free and do not encounter obstacles.
My expertize covers also nanotechnologies, which are in this case to avoid: the particles are very effective in colour renedering, but extremely Dangerous for human health. Most probably, to have healthy colored smoke, you need dye particles in the range of microns, which are catched by human natural defense systems in nose and lungs.
Nevertheless, I'm available to discuss ideas with you. I have a chemical laboratory with all chemicals and facilities available for experimental campaigns, if required.
Best Regards,
Marco Stoller