A Brief History of Silica Exposure in the United States

During the Great Depression, many workers were laid off and hunting for jobs in the United States. Work was hard to come by and surviving employers were seeking efficiency and stability – much like we are seeing today during the pandemic. As businesses tightened up, so did the evaluations of incoming workers. Laid off foundry workers and miners were dealt a major blow when pre-employment tests revealed they had severe lung damage from occupational exposure to respirable crystalline silica (RCS). The findings among these hard-working blue-collar men marked the beginning of widespread interest in the occupational disease known as silicosis.

Hawk’s Nest Disaster

Paralleling the hit to foundry workers and miners was the Hawk’s Nest Tragedy in West Virginia in the 1930’s. Construction of a three-mile tunnel through Gauley Mountain in West Virginia required drilling and blasting of rock containing the naturally occurring mineral, silica. Respirable dust was created inside the tunnel from rock containing exceedingly high levels of silica. Within a year of the project launch, workers began experiencing accelerated onset of silicosis. The disease typically takes 10 to 30 years to show in consistently exposed workers. However, hundreds of workers, mostly African American, died by the time the project had finished. Many more experienced silicosis onset years after the tunnels completion. The Air Hygiene Foundation was developed in response to this tragedy and silicosis became a compensable occupational disease.

Sandblasting in the West Texas Oil Fields

Between the 1930’s and 1970 there were not many cases of silicosis reported among workers in the United States. However, in the 1970’s many more cases began to emerge as the economy boomed. Over the next two decades clusters of silicosis cases emerged among oil and gas workers in West Texas. Many of the cases were linked back to sandblasting operations in the industry. Today, the industrial sand used in hydraulic fracturing is also a known hazard to the health of oil and gas workers.

Brief Overview 1971 – 2015

Slow forward to 1971 – Things get a little more technical. Shortly after the inception of OSHA, permissible exposure limits (PELs) for occupational exposure to RCS were adopted. For general industry the PEL was initially 100 micrograms per cubic meter (μg/m3) as an 8-hour time weighted average (TWA). Construction and shipyard PELs were 250 μg/m3 for an 8-hour TWA. Various Special Emphasis Programs (SEPs) were implemented by OSHA between 1980 and 2008. Data from those programs showed widespread noncompliance with RCS PELs.

In 2008, OSHA implemented a National Emphasis Program (NEP) with a goal of reducing or eliminating occupational exposure to RCS in construction and general industry. Samples collected throughout the NEP still showed 25-30 percent noncompliance with RCS PELs in construction and general industry. Even with a 70-75 percent compliance rate, workers still suffered from silicosis due to unacceptable PELs and gaps in appropriate controls.

New RCS Standards Issued in 2016

In 2016, OSHA issued new RCS standards for general industry and maritime (1910.1053) and construction (1926.1153). Both standards present a new action level for employers of 25 μg/m3 and a PEL of 50 μg/m3 with an 8-hour TWA. New compliance rules were also implemented for use of engineering controls to limit exposures to the PEL, and employers are required to offer medical exams to employees exposed above the PEL for 30 days or more. Detailed requirements in each standard can be found on the OSHA website. Compliance dates for each component of the new standards vary by industry.

2020 National Emphasis Program

The Occupational Safety and Health Administration put the new Respirable Crystalline Silica (RCS) National Emphasis Program (NEP) in place February 4, 2020. The NEP targets industries that are expected to have high exposures to RCS. If your industry was determined to be in a high-risk category, your company may have received a letter from OSHA with information about the emphasis program. If you are not sure if your industry made the list, check Appendix A of the directive.

What You Should Know

Health hazards are commonly overlooked in safety programs, especially when the onset of disease is delayed. Crystalline silica is a naturally occurring mineral commonly found in sand, stone, and concrete. When respirable dust is generated during work activities, the small particles can be inhaled and make their way through the respiratory tract and into the lungs. Over time, exposure to RCS particles can cause and lung disease called silicosis that can lead to disability and death. RCS exposure may also lead to COPD, kidney disease or lung cancer. RCS particles can also be found in environments where grinding, crushing, drilling, or cutting of rock, stone, brick, and mortar are occurring. From oil and gas workers to unsuspecting electrical workers on commercial and residential job sites, there is a lengthy list of individuals who are being exposed to RCS.

As an employer or individual contractor, it is important to follow some simple steps to start protecting workers and your business:

  • Determine if workers are potentially being exposed to respirable silica.

  • If workers are being exposed, measure the level of exposure using existing sampling methods and qualified laboratories.

  • Implement controls if results indicate workers are exposed above the action level or PEL.

  • Check the effectiveness of the controls.

Additional Information

Small businesses can take advantage of OSHA’s On-Site Consultation Program.

It is also important to understand that the AIHA and NIOSH often provide more up to date/stringent guidelines to protect workers than OSHA.

Contact an Occupational Safety and Health professional to learn more about silica program requirements.

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