Originally Posted by
John Stevens
For a person who will be exposed to the dust for up to ten hours a day, and up to 40 hours a week, the "permissible exposure limit" for "total dust" is 15mg/m^3. If you limit the dust to what is called the "respirable fraction," the limkt is 5mg/m^3, still five times the figure stated in the earlier thread. OSHA also gives these exposure limits as particle numbers as measured by "impinger samples counted by light-field." These particle number limits are 50 million particles/cu.ft. for total dust and 15 million particles/cu.ft. for the respirable fraction of dust.