Safety and OSHA News

OSHA’s proposed silica rule: What you need to know

What changes to its respirable silica standard has OSHA proposed, and how does the new permissible exposure limit (PEL) compare to those in other countries?

Under the proposal, workers’ exposures would be limited to a new PEL of 50 micrograms of respirable crystalline silica per cubic meter of air (µg/m3), averaged over an 8-hour day. The National Institute of Occupational Safety and Health had recommended 50 µg/m3 as the new standard.

The current PEL is 100 µg/m3 for general industry and 250 µg/m3 for construction.

The new standard would also set an action level of 25 µg/m3. The action level would require employers to conduct periodic exposure monitoring for employees.

The proposed rule also includes:

  • provisions for measuring how much silica workers are exposed to
  • limits on workers’ access to areas where silica exposures are high
  • medical exams for workers with high silica exposures, and
  • training for workers about silica-related hazards and how to limit exposure.

The standard would make controlling silica dust the primary method to reduce employee exposure. Rules about personal protective equipment are included, but PPE would be a last resort to reduce exposure.

Lowering silica exposure can generally be done through dust control measures such as:

  • wetting work areas to keep the dust from getting into the air
  • enclosing a work area (process isolation), or
  • using a vacuum to collect dust at the point where it’s created before workers can inhale it.

OSHA estimates the rule will cost the average affected facility $1,242 per year. The cost for small facilities with fewer than 20 employees would be less: about $550. OSHA says the rule isn’t expected to have a discernible impact on total U.S. employment.

Workers who inhale tiny silica particles are at risk of developing silicosis (an incurable and sometimes fatal lung disease), lung cancer, chronic obstructive pulmonary disease, other lung disorders and kidney disease.

The update in the silica rule had been delayed up to 10 years. It will still be a while before it’s official: Public hearings aren’t expected until March 2014.

Is U.S. proposal too strict?

The National Industrial Sand Association is one group that criticized the proposal to lower the PEL. It says companies that belong to the group have already successfully protected their workers under the current PEL.

So how does the proposed new U.S. PEL compare to ones in other countries?

  • Great Britain: 100 µg/m3
  • Canada: 50 µg/m3
  • South Africa: 100 µg/m3
  • Australia: 50 µg/m3.

The World Health Organization’s Scientific Committee on Occupational Exposure Limits had recommended 50 µg/m3 to prevent silicosis in a report issued in 2003.

The American Conference of Governmental Industrial Hygienists recommended a 25 µg/m3 exposure limit.

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