Sources: OSHA, CP staff
The Notice of Proposed Rulemaking for Occupational Exposure to Respirable Crystalline Silica (NPRM) profiles 11 ready mixed and manufactured concrete production job titles, estimating at least half of workers with three of them encounter silica exposure above the agency’s new 50 microgram per cubic meter of air over eight-hour sampling period (50 μg/m3).
All mixer truck drivers have silica exposure rates above 250 μg/m3, according to the NPRM, followed by abrasive blasting operators (33 percent) and packaging operators (16 percent)—the latter two in manufactured-concrete plant environments.
The proposed 50 μg/m3 PEL for quartz matches OSHA’s existing threshold for two other forms of respirable crystalline silica, cristobalite and tridymite, in general industry workplaces. The 756-page NPRM includes separate standards for general industry and construction, detailing for both sectors widely used methods to control worker exposure, conduct medical surveillance, train workers about silica-related hazards, and record compliance measures.
In a table of annual compliance costs for businesses with 20 or fewer employees, the NPRM offers estimates for the industrial classifications spanning concrete production: Ready mixed concrete, $1,328; Concrete block and brick, $1,608; Concrete pipe, $1,741; and, Other concrete products, $1,422. Compliance measures for the proposed rule include engineering controls, respirators, exposure monitoring, medical surveillance, and training.