In 2016, the Occupational Safety and Health Administration announced new respiratory silica exposure levels that lowered the action level for exposure to 25 micrograms per cubic meter of air. The maximum permissible exposure limit for silica drops to 50 micrograms per cubic meter. Exposure control and medical monitoring requirements based on these new exposure levels take effect for general industry and the maritime industry on June 23, 2018.
 
Common sources of airborne silica exposure include stone cutting, sand blasting, and other uses of industrial sand. Employers affected by the new standards should have a written exposure control plan in place by this date. The plan needs to include measures for determining silica exposure levels, as well as engineering, personal protective equipment, and other exposure control methods. It also requires housekeeping, medical monitoring, and employee training. Employers with existing plans should update their terms to account for the new exposure levels. An OSHA fact sheet on silica exposure can be found here.