Photo by Tony Bodway, Silica/Milling Machine Partnership
NIOSH-industry-labor partnership has been testing anti-silica-dust options, such as this water sprayer system, on milling equipment.

After more than a decade of study and review, the Occupational Safety and Health Administration has proposed a much tighter limit on how much airborne silica dust workers can be exposed to, a move that agency officials say will prevent hundreds of deaths and illnesses among construction workers each year.

The long-awaited proposal, which OSHA released on Aug. 23, has two parts: a new exposure limit and other requirements for the construction industry and a standard for maritime workers and other industries.

OSHA is proposing the same new permissible exposure limit, or PEL, for construction and non-construction industries: 50 micrograms of crystalline silica per cubic meter of air, averaged over an eight-hour day.

That level is much more stringent than the current limits, which were put in place 40 years ago and that OSHA says are outdated.

OSHA chief David Michaels told ENR in an interview that the current PEL for construction is the equivalent of 250 micrograms but adds that it is based on an “obsolete” measurement system. “No one can use that method any more,” he says.

The current limit for non-construction industries is 100 micrograms.

OSHA says the proposed regulation will provide particular benefit to construction workers who encounter silica dust in tasks such as crushing rock, milling pavement and using masonry saws, jackhammers and drills.

Michaels says, “This will save more lives in the construction industry than any proposal OSHA has worked on in many years and perhaps ever.”

OSHA projects that if the rule is made final and fully put into effect, it would annually save the lives of 700 workers, 80% of them in construction, and prevent 1,600 new cases of silicosis, 68% of them in construction.

Peg Seminario, the AFL-CIO’s director of safety and health, in an interview said, "The majority of workers who are exposed and overexposed [to silica] are in the construction industry." She added, "The standard will go a long way to helping reduce exposures and reduce unnecessary disease and death.”