0.05 mg/m3 is NIOSH’s respirable crystalline silica Recommended Exposure Limit (REL) but many worker’s exposure exceed this limit.
Construction workers involved in asphalt pavement mining are among the workers who are the most at risk of being overexposed to respirable Crystalline Silica.
To protect these workers from personal injury related to overexposure to crystalline silica, the National Institute for Occupational Safety and Health (NIOSH) has worked with an array of industry stakeholders — heavy/highway construction contractors, labor organizations, equipment manufacturers, and government officials — to identify solutions. They recently published guidelines and industry best practices to control construction workers exposure to this dangerous dust during Asphalt Pavement Milling. The complete document can be downloaded here. A brief Field Guide for Controlling Silica Dust Exposure on Asphalt Pavement Milling Machines produced by CPWR, NIOSH and NAPA is also available.