Criteria for updating the crystalline silica gel

The final rule sets a new permissible exposure limit (PEL) for respirable crystalline silica of 50 micrograms per cubic meter of air calculated as an eight-hour time-weighted average (TWA).

“We weren’t sure that within two years that industry would be able to widely adopt and disseminate all this new technology.” The final standards include several changes from the proposed standards based on OSHA’s analysis of written comments and testimony on the proposed rule.During a call with reporters to introduce the new rule, Secretary of Labor Thomas E. workers are exposed to respirable crystalline silica, including approximately two million construction workers and 300,000 workers in general industry operations such as brick manufacturing, foundries, and hydraulic fracturing.Perez stated that the new PEL is “precisely what NIOSH recommended” more than 40 years ago in its 1974 criteria for a recommended standard on occupational exposure to crystalline silica. Under the new rule, employers will be required to use engineering controls to limit worker exposure to the PEL; provide respirators when engineering controls cannot adequately limit exposure; and limit worker access to high exposure areas.The agency originally proposed that the standard for general industry and maritime should apply to exposures resulting from the processing of sorptive clays, which are used in consumer products and industrial applications.According to Michaels, the specific mention of sorptive clays was dropped following OSHA’s review of the geology and chemistry of the clays, which did not indicate the same characteristics as some of the other exposures covered by the rule.

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