A final rule requiring employers to monitor and substantially reduce worker exposures to breathable crystalline silica—otherwise known as silica dust—will save more than 600 lives annually and protect the health of thousands of others, according to the Occupational Safety and Health Administration and a number of labor unions that support the rule.

Silica-dust exposure, common on construction and industrial sites, can cause life-threatening health problems such as asthma, lung cancer and silicosis.

Labor unions have long fought to toughen the standard, which hasn’t been updated since the 1970s. But construction industry groups say the new permissible exposure limit (PEL) of 50 micrograms per cu meter of air over an eight-hour period, half the level permitted under the former standard for general industry, is not achievable with existing technology. They have filed a lawsuit to challenge the rule.

Announced on March 24, the new rule contains two standards: one for construction, the other for general industry and maritime. Effective June 23, contractors have until June 23, 2017 to comply.

The rule for construction requires employers to use engineering controls, such as water or ventilation, to limit worker exposure to silica dust and provide respirators when engineering controls cannot adequately limit exposure. Employers also must develop a written exposure-control plan, offer medical exams to highly exposed workers, and train workers on silica risks and how to limit exposures.

It also includes some alternative routes to compliance for small employers and a “safe harbor provision” that enables some employers to opt out of regular air-quality monitoring if they provide sufficient controls.

In announcing the rule at the International Masonry Institute Training Center in Bowie, Md., on March 24, Labor Secretary Tom Perez said, “The final rule is the product of an extensive public outreach effort and active engagement of all stakeholders. We’ve approached this rule-making with a keen ear and an open mind. We’ve built a big table and invited everyone to pull up a chair.”

Construction-industry employer groups argue that OSHA disregarded their evidence during the development of the regulation. They maintain that the rule is technically and economically infeasible. A coalition of eight associations, including chapters and headquarters of the Associated Builders and Contractors, the Associated General Contractors of America, and the American Road and Transportation Builders Association, filed a lawsuit challenging the final rule on April 4.

Kevin Cannon, AGC’s safety director, says, “What we’ve been hearing from our members is that they truly can’t hit the 50-micrograms-per-cubic-meter mark,” even using the controls recommended in the rule. AGC would have preferred that OSHA better enforce the existing standard, he adds. Moreover, data from the National Institute of Occupational Safety and Health show that deaths from silicosis are going down.

“I categorically reject the claim that the sky will fall if we give our workers the strongest possible protections.”

— Tom Perez, U.S. Labor Secretary

Chris Trahan, speaking on behalf of the North America’s Building Trades Unions, counters that deaths from silicosis and other silica-related diseases are vastly underreported. “We do a terrible job of monitoring for occupational illnesses in this country. There is a general lack of awareness in the medical community, outside of occupational physicians of silica-related disease in general or even of silicosis.”

Some workers who have been diagnosed with silicosis are afraid to disclose their status for fear of discrimination by employers, Trahan notes, adding, “It’s not just a theory that, once it is known that a worker has silicosis, that there is going to be discrimination.”

Trahan says the new PEL is achievable using equipment available now.

The silica regulations faced scant opposition from tool and equipment manufacturers, which, in some cases, welcomed clarification on limits they knew were coming well in advance.

“Our company was kind of ahead of North America because we are already in European markets with more regulations,” says Aaron Brading, manager for Hilti’s business unit for power tools and accessories. Hilti manufacturers its own dust-collection systems, meant to be used with its line of concrete breakers, hammer drills and masonry saws. The Swiss-based company is well aware of health concerns about silica dust.

While the OSHA regulation offers specifications on the number of microns of silica allowable in a given volume of air, Brading says dust-control equipment makers probably will target the “safe harbor” part of the standard since it is a more realistic target on a busy jobsite.

Under the “safe harbor” definition, an employer is considered to meet the standard if dust-control equipment is deployed, with no need to spot-check the ambient silica levels. “It’s less risk from our perspective,” says Hilti’s Brading. “[Silica dust] measurement rules will come across as very technical in the construction space. So, going for ‘safe harbor’—with self-cleaning tools and a wet vacuum—will work better for contractors.”

On larger construction machinery with silica-dust issues, manufacturers have been working with OSHA. Asphalt paving can generate silica dust during road milling, so the National Asphalt Pavement Association has been involved in advising OSHA during the rule-making process. “At first blush, it appears OSHA acknowledged the information we brought forward during the rule-making process, demonstrating that the agency’s initial requirements for respiratory protection during asphalt-pavement milling operations were unnecessary,” says Howard Marks, NAPA vice president. “Many newer existing milling machines already have these controls in place, and manufacturers have pledged to have them on all half-lane and larger mills starting in January 2017. In addition, retrofits will be made available for older-model milling machines.”

The dangers of acute silicosis first received national attention during the Depression, as a result of the Hawk’s Nest Tunnel project. New Kanawha Power Co., which was controlled by Union Carbide, hired contractor Reinhart & Dennis Co. to excavate a three-mile-long tunnel in West Virginia for a hydroelectric project. Sections of the tunnel route were pure silica. To save time, the contractor often failed to use water to suppress drill dust as workers cut through the silica. The tunneling was carried out from March 1930 to December 1931.

Many of the 2,500 workers suffered from acute silicosis in the ensuing years, and an unknown number died. Documenting these deaths was difficult, as most were migrant workers who dispersed across the rural South after their employment ended. Martin Cherniak’s epidemiological study, published in 1986, concluded that, within five years of the tunnel’s completion, 764 workers likely died from silicosis or other “causes of deaths from dusty lungs.”

Within two years of the project’s completion, suits claiming illness or death from silicosis were brought on behalf of 336 tunnel workers or their survivors. Suits totaling $4 million were settled for $130,000.

News articles about the tunneling and its consequences triggered a series of congressional hearings in 1936. The subcommittee’s report concluded that tunnel builders ignored the silica-related health hazards and preventative exposure methods, even after unmistakable patterns of disease had emerged.

During his remarks on March 24, Perez referred to Hawk’s Nest and said the new rule is necessary.

“I categorically reject the claim that the sky will fall if we give our workers the strongest possible protections,” Perez said. “History simply doesn’t support that conclusion. To suggest otherwise is a false choice.”