Exposure Assessment | Asbestos

Q.	What is included in the new "exposure assessment" requirements in the Construction and Shipyard standards?
A.	The "exposure assessment" predicts exposure and evaluates potential controls. In most cases, the exposure assessment will include both past and current monitoring. Monitoring results must be considered, but do not necessarily constitute an adequate "assessment" if they would not represent all representative employee exposures during the entire job. The assessment must review relevant controls, conditions and factors that influence the degree of exposure. These include, but are not limited to, quality of supervision and of employee training, techniques used for wetting the ACM, placing and repositioning the ventilation equipment and impacts due to weather conditions. The assessment must be based on a review of all aspects of the employer's performance doing similar jobs.
Q.	Do all employers need to conduct an "initial exposure assessment" under the Construction standard?
A.	In general, all employers who have a workplace covered by this standard are to conduct an "initial exposure assessment" at the beginning of each asbestos job [paragraph (f)(2)]. Exceptions to this requirement exist only for most Class IV work. Even employers who are planning to install full negative pressure enclosures with air flushing technology must conduct initial exposure assessments. Employers may base assessments of similar jobs on prior assessments of repetitive, routine jobs.
Q.	Is it more difficult than before to base an initial exposure on "historic data"?
A.	Yes, the standard establishes specific evaluation criteria for data. This criteria included the experience and training of the crews and the historic data must be updated annually. It is important to note that historic data is usually that data generated by an individual employer, whereas objective data is related to a product, material, or activity and may be derived from other employers' (such as the manufacturer of the product) data.
Q.	Explain "objective data."
A.	The use of objective data grants a monitoring exemption and may be used as a basis for a "negative exposure assessment." The employer using "objective data" must demonstrate that the product or material containing asbestos minerals or the activity involving such product or material cannot release airborne fibers in concentrations in excess of the PEL under those work conditions having the greatest potential for releasing asbestos. The employer may use data derived from other employers' jobs. The data should reflect worst case conditions in a variety of occupational settings.
Q.	When can "objective data" be relied on for a negative exposure assessment?
A.	For any specific asbestos job (combination of activity and product) performed by employees who have been trained in compliance with the standard the employer must demonstrate that, under worst case conditions, statistically there is a high degree of confidence that an exposure above the permissible exposure limit will not occur.
Q.	How would an employer who performs repetitive work complete exposure assessment?
A.	An employer may evaluate repetitive operations with highly similar characteristics, as one job, such as cable pulling in the same building, so long as the data used also reflect repetitive operations of the same duration and frequency.
Q.	Did OSHA adopt a clearance level?
A.	OSHA has not included a provision for a specific "clearance level" in the revised standards.