The U.S. Department of Labor’s Occupational Safety and Health Administration (OSHA) issued a memorandum outlining the initial enforcement of the standard for respirable crystalline silica. Most provisions of the standard become enforceable on June 23, 2018.

The standard establishes a new 8-hour time-weighted average permissible exposure limit, action level and other requirements.

During the first 30 days of enforcement, OSHA will offer compliance assistance for employers who make good-faith efforts to comply with the new standard. OSHA intends to issue interim enforcement guidance until a compliance directive on the new standards is finalized.

The silica rule is intended to limit workers’ exposure to respirable crystalline silica. It reduces the permissible exposure limit (PEL) for workers to 50 micrograms per cubic meter of air, averaged over an eight-hour shift. It also requires employers to implement engineering controls, offer medical exams and develop control plans related to the issue.

According to OSHA, as many as 2.3 million workers, many in the construction and manufacturing industries, will be affected by the rule.

Silica is a key ingredient in the manufacture of glass. OSHA says the most severe exposures to crystalline silica result from abrasive blasting. It’s used in many industrial applications, such as etching or frosting glass. Additionally, crystalline silica exposure can occur in the maintenance, repair and replacement of the linings of refractory brick furnaces, such as those used to manufacture glass. Other exposures to silica dust occur in china and ceramic manufacturing and the tool and die, steel and foundry industries.