The standard does not include a specific exemption for tasks with only short-term exposures (e.g., tasks with exposures for 15 minutes a day or less). However, in many cases, employees who perform construction tasks for very short periods of time, in isolation from activities that generate significant exposures to silica (e.g., some tasks listed on Table 1, abrasive blasting), will be exposed below the AL of 25 μg/m3 as an 8-hour TWA under any foreseeable conditions. Short-term silica exposures must be very high in order for those exposures to reach or exceed 25μg/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-hourTWA exposure would be at or above 25 μg/m3. See 81 Fed. Reg. at 16706. 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. See 81 Fed. Reg. at 16706. 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 AL 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 standard.
October 2018
Tags: OSHA