web analytics
Home | Columnists | OSHA | OSHA - Some frequently asked questions about the OSHA Silica law

OSHA - Some frequently asked questions about the OSHA Silica law

image Joann Natarajan, Compliance Assistance Specialist, OSHA, Austin, TX

DALLAS/FT WORTH - OSHA’s silica standard for construction applies to all occupational exposures to respirable crystalline silica in construction work, except where employee exposures will remain below 25 μg/m3, calculated as an 8-hour Time Weighted Average, under any foreseeable conditions. The exception applies only where exposures below 25 μg/m3 as an 8-hour TWA are expected or achieved without using engineering or other controls.

 

 


1.  Has OSHA identified specific tasks that are likely to be outside the scope of the law because they typically generate exposures below the Action Limit of 25 μg/m3 as an 8-hour Time Weighted Average under all foreseeable conditions?
    Yes.  When the following tasks are performed in isolation from other silica-generating tasks, they typically do not generate silica at or above the AL of 25 μg/m3 as an 8-hour Time Weighted Average under any foreseeable conditions: mixing small amounts of mortar; mixing small amounts of concrete; mixing bagged, silica-free drywall compound; mixing bagged exterior insulation finishing system (EIFS) base and finish coat; and removing concrete formwork. In addition, tasks where employees are working with silica-containing products that are, and are intended to be, handled while wet, are likely to generate exposures below 25 μg/m3 under any foreseeable conditions (examples include finishing and hand wiping block walls to remove excess wet mortar, pouring concrete, and grouting floor and wall tiles).

2.  Does the OSHA law cover workers who they are exposed to silica for 15 minutes per day?
    The standard does not include a specific exemption for tasks with exposures for 15 minutes a day or less.  However, employees who perform construction tasks for very short periods of time, in isolation from activities that generate significant exposures to silica, will be exposed below 25 μg/m3 as an 8-hour Time Weighted Average (TWA) under any foreseeable conditions.  Short-term silica exposures must be very high in order for those exposures to reach or exceed 25 μg/m3 as an 8-hour TWA; for example, if an employee is exposed for only 15 minutes, his or her exposure would have to be higher than 800 μg/m3 for that 15-minute period before the 8-hour TWA exposure would be at or above 25 μg/m3.  Some examples of tasks that could generate very high short-term exposures include abrasive blasting and grinding, which are typically associated with high levels of visible dust.
    OSHA has identified carpenters, plumbers, and electricians as types of workers who may perform tasks (e.g., drilling with a handheld drill) involving occasional, brief exposures to silica that are incidental to their primary work.  Provided that these employees perform these tasks in isolation from activities that generate significant exposures to silica, and perform them for no more than 15 minutes throughout the work day, their exposures will usually fall below the Action Limit of 25 μg/m3 as an 8-hour TWA under all foreseeable conditions; when that is the case, these employees will not be covered by the law.
natarajan.joann@dol.gov
512-374-0271 x232


Need a Reprint?


   
Author Info

CN Contributor info@constructionnews.net