OSHA has released its final rule on protecting workers from exposure to silica, marking the agency's first updated regulation for the material since 1971.

The agency estimates that the rule will save more than 600 lives and prevent more than 900 cases of silicosis - an incurable lung disease - each year. The rule also is intended to help protect against lung cancer, chronic obstructive pulmonary disease and kidney disease.

The new permissible exposure limit for respirable crystalline silica - 50 micrograms per cubic meter of air averaged during an 8-hour shift - matches what NIOSH recommended in 1974. OSHA's new PEL is half the previous limit for general industry and 5 times lower than the previous limit for construction.

"Unfortunately, it has taken over 40 years for the politics to catch up with the science," Secretary of Labor Thomas Perez said during a March 24 press conference. "In the meantime, the industry has changed, technology has progressed, businesses have innovated. A good government also adapts, even if it's long overdue."

Under the previous rule, employers simply had to stay below the permissible exposure limit, OSHA administrator David Michaels said during the press conference. "But they wouldn't have to do anything other than that, and we would go into worksites and measure and often find lack of compliance."

The new rule covers engineering controls, protective clothing, medical surveillance and other issues. OSHA presents the rule as two standards - one for general industry and maritime and the other for construction. Highlights include:

• Lowering the permissible exposure limit for crystalline silica to 50 micrograms per cubic meter of air averaged during an 8-hour shift.
• Mandating that employers use engineering controls and work practices to restrict worker exposure, bar access to high-exposure sites, supply respiratory protection when controls cannot curb exposures to the PEL, train employees, and offer medical exams to highly exposed workers.
• Offering a table of specified controls that construction employers can follow for "greater certainty and ease of compliance" without monitoring exposure.
• Allowing employers to have enough time to satisfy requirements by spacing out compliance dates.
• OSHA created the table in response to small construction employers' claims that measurement is expensive and difficult, Michaels said, adding that construction employers can avoid measuring by following the table's principles.

Both standards are scheduled to go into effect on June 23, 2016. Industries will then have one to five years to meet most requirements. The construction industry must comply by June 23, 2017; general industry, maritime and hydraulic fracturing must adhere to requirements by June 23, 2018; and hydraulic fracturing will have until June 23, 2021, to comply for engineering controls. The extended time allows employers to provide medical exams to some workers, and gives hydraulic fracturing employers the opportunity to implement dust controls for the new PEL, OSHA state