>?
I¡¯m no expert, but I think that is why Felder (and others) quote amounts/volumes, rather than sizes?
Presumably the reason they use mg/m3 is because that's the standard medical exposure metric. ?For example, OSHA doesn't specify filter size, it specifies the maximum quantity (in mg) of dust that can be present in each cubic meter of air in the workplace. ? This metric does not factor particle size, but I believe the threshold assumes a typical particle size distribution -- that is to say, if you are under the threshold, you can assume you are safe regardless of the particle size distribution. ?
Fwiw, the NIOSH exposure limit is 1mg/m3.?
