The U.S. Occupational Safety and Health Administration (OSHA) issued its official interim enforcement guidelines for the newly-implemented silica standard.

The key provision of the rule with the greatest potential impact to roofing contractors is the reduction of the allowable exposure limit from 250 to 50 micrograms per cubic meter of air averaged over a traditional eight-hour shift. The standard was approved last year but implementation was delayed until last September while the agency developed guidelines for enforcement of the controversial changes.

A lawsuit filed last year by seven national trade associations to block the rule was recently dismissed. The guidelines are designed for OSHA inspectors to follow, but are noteworthy for roofing contractors because they cover everything from exposure assessments to methods of compliance including the medical surveillance provisions. It also lays out possible penalties for failing to comply.

A full list of the guidelines is available on the OSHA website (