When atomising powder gold, powder silver and metal pigments, a DUST/PARTICULATE MASK must be worn. Metal pigments (not in Modulor´s product line) are highly noxious and as a result are classed as dangerous goods. Breathing in only a small amount can already lead to a very unpleasant zinc sickness that is harmful to health. If you nonetheless do work with metal pigments, be absolutely sure that you have read the relevant safety data.
Neither powder gold nor powder silver are noxious – breathing in the extremely fine powder should nonetheless be avoided (particulate matter!).