Page 40 - Occupational Health & Safety, October 2017

INDUSTRIAL HYGIENE
Preventing Worker Exposure to Silica Dust
OSHA has provided three different methods for employers to ensure employees are protected. BY TIM TURNEY
sion from groups including employers and labor- ers, who have called OSHA’s predications infeasible, even questioning the link between respirable crys- talline silica and subsequent long latency condi- tions, such as lung cancer and chronic obstructive pulmonary disorder.
Prior to the agreed enforcement date, OSHA ex- pects employers to move toward compliance to the new permissible exposure limit (PEL) of 50 μg/m3, averaged over an eight-hour workday, similar to Eu- ropean countries.2 In a bid to make this process easier, OSHA has provided three different methods for em- ployers to ensure employees are protected.
These methods are:
Table method: A table has been created listing the different tasks and equipment control methods that OSHA has determined will reduce the exposure to the acceptable level, taking different times and envi- ronments into consideration. If the task controls and equipment are provided, there is no additional need for air monitoring.
Performance or objective data: With this meth- od, employers are permitted to use objective data to provide evidence that the control methods reduce the exposure limit to below the PEL. This could be air monitoring compiled by the employer or a third party that is sufficient to indicate the exposure. The data provided must reflect conditions that are simi- lar or worse than the employer’s current work site conditions.
Scheduled air monitoring program: In this in- stance, exposure can be assessed through a dedicated air monitoring program where the employer gener- ates its own data. Employers using this option are required to implement such a program when work- ers are exposed over the 25 μg/m3 action level over an eight-hour control period, and also to implement control methods.
To comply with the standard, the following sched- ule must be adhered to:
■ If initial results indicate exposures are below the action level (25 μg/m3), no additional monitoring is necessary.
■ If the monitoring results indicate exposures are above the action level but below the PEL, additional monitoring would be required within six months.
■ If the exposure monitoring indicates exposures above the PEL, additional monitoring must be repeat- ed within three months.
■ If subsequent monitoring (not the initial moni- toring) indicates exposures are below the action level, the employer must repeat the monitoring until two consecutive measurements (taken seven or more days apart) are below the action level. At that point, the em-
The introduction of OSHA’s latest respirable crystalline silica standard has not been without difficulty. Implementation dead- lines have been changed, and now enforce- ment was to begin in the construction industry on Sept. 23, 2017.1 The standard has generated discus-
36 Occupational Health & Safety | OCTOBER 2017
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