OSHA newer and more stringent regulations regarding employee’s exposure to respirable crystalline silica officially went into effect on September 23, 2017.  The new reduced the permissible exposure limit of the substance, which is found mostly in products containing sand (like concrete, mortar, and brick), from 250 micrograms per cubic meter of air down to 50 micrograms per cubic meter of air averaged over an 8 hour shift.