According to OSHA.gov, the rule changes:
Reduce the permissible exposure limit for crystalline silica to 50 micrograms per cubic meter of air, averaged over an eight-hour shift.
Require employers to use engineering controls (such as water or ventilation) and work practices to limit worker exposure; provide respiratory protection when controls are not able to limit exposures to the permissible level; limit access to high exposure areas; train workers; and provide medical exams to highly exposed workers.
Provide greater certainty and ease of compliance to construction employers - including many small employers - by including a table of specified controls they can follow to be in compliance, without having to monitor exposures.
Staggered compliance dates to ensure employers have sufficient time to meet the requirements, e.g., extra time for the hydraulic fracturing (fracking) industry to install new engineering controls and for all general industry employers to offer medical surveillance to employees exposed between the PEL and 50 micrograms per cubic meter and the action level of 25 micrograms per cubic meter.
June 23, 2017 - Construction Enforcement Date
June 23, 2018 - General Industry/Maritime Enforcement Date