Document z6zv3kLgpMvgx2vawKKOMDDm

22684 Federal Register / Vol. 51, No. 119 / Friday, June 20, I960 / Rules and Regulations monitoring of employees who are, or requires the employer to sample based may reasonably be expected' to be on performance criteria. That is, the exposed to airborne concentrations at or employer must sample with such above the action level. Thus, for frequency and pattern as to represent, example, because office buildings with reasonable accuracy, the levels of generally have air concentrations less exposure of the employees. This than the action level, an employer would performance provision is contained in not be required to perform initial the existing standard and is maintained monitoring unless there is'reason to in the final standard. In this provision, believe that conditions exist that may the employer decides how often to expose employees to asbestos at or monitor, depending upon the conditions above the action level. Such conditions in the employer's operation: some include visible evidence of deterioration employers may monitor more than of asbestos materials and construction others providing the monitoring is a I or maintenance activities which would least on a semiannual basis for all. disturb asbestos materials. Clearly, the more frequent the The final rule does not require measurements, the greater the reliability periodic monitoring and measurement of the resulting employee exposure for the TWA when initial monitoring profile. data reveal exposures below the 0.1 f/cc A number of submissions to the action level because exposures below record supported a requirement for the action level provide a margin that monitoring every three months if the . makes it unlikely that minor changes in airborne concentration of asbestos was processes, materials or environmental at or above the action level [Exs. 84-379, conditions will result in exposures 127). For example, the European above the PEL. . Economic Community, Labour and Many commenters addressed the Social Affairs Council (1983). stated: specifications for monitoring frequency contained in the proposed standard [Exs. 84-379, 88-4. 90-140, 90-168, 90- The concentration of asbestos shall be measured us a general rule ot leas) every three months and, in any case, whenever a 173,127, 283, 42B}. Several commenters technical change is introduced [Ex. B4-379I- requested that OSHA not specify a frequency for monitoring employee exposure levels [Exs. 88-4,90-173, 263J. For example, the American iron and Steel Institute stated: .And, Marshall H. Marcus, certified industrial hygienist, supported the change in monitoring frequency, commenting that exposure monitoring should be reduced to once every three Required exposure sampling should have a months, with provisions for additional valid;basis. An automatic preset sampling frequency-is burdensome, wastes scarce industrial hygiene resources, and provides no direct benefit to exposed,employees who follow proper work practices and use prescribed personal protective equipment'. * * * Requiring sampling on a quarterly basis serves little purpose if the jobs performed are monitoring if necessary [Ex. 127], The standard requires that whenever there has been a production, process, or control change that may result in new or additional exposures to asbestos above the action level, or whenever the employer haB any other reason to essentially the same and no changes have Buspect an increase in employee occurred lii the operation [Ex. 283]. exposures above the action level, the Bell Communications Research also addressed this point: The requirements for exposure monitoring should be written in terms of performance oriented language that will allow employers to structure their monitoring program to fit theirsperificwork situation. ' * 'Overall employer shall again initiate the required monitoring for those employees affected by such change or increase. The final standard also provides that an ' employer may discontinue periodic monitoring for those employees for ' whom measurements statistically show employee protection is more dependent'on exposures to be below the action level. training, work procedures; and in some cases personal protective equipment than a rigid workplace monitoring program [Ex. 90-173). . The final standard also differs from the existing standard in that the requirement to conduct environmental OSHA has maintained the.monitoring monitoring has been eliminated in the frequency in the existing standard. final standard, and the frequency of However, OSHA believes that the personal monitoring is increased. The monitoring frequency specified in the purpose of the OSHA standard is to final standard is. a minimal requirement, reduce worker exposure. Only air and that.many employers will wish to samples collected at the worker's conduct more frequent monitoring to breathing, zone truly reflect the level of . ensure employee protection and exposure of a worker to a given compliance with the standard. Although contaminant throughout a work day. the final standard contains a minimal Therefore, OSHA believes that personal sampling frequency, the final standard air sampling is more useful than environmental sampling for determining compliance for the OSHA standard. Environmental samples can be useful. When the purpose of a survey is to determine sources of contamination or to evaluate engineering controls, a network of area sampling (environmental monitoring) would be appropriate. The new standard permits this type of sampling. OSHA has not required, however, that the employer conduct environmental sampling in other toxic substance regulations, and has found that personal air sampling is adequate as a mandatory requirement. In addition, the elimination of environmental sampling permits the employer to make more efficient use of resources. Methods of Measurement In the April proposal (49 FR 14128), OSHA considered requiring a specific sampling and analytical protocol to measure and analyze airborne concentrations of asbestos fibers. Currently, the existing asbestos standard (29 CFR 1910.1001(e)) requires that all measurements of asbestos fibers be made by a membrane filter method using phase contrast illumination at 400500 X (magnification). While acknowledging that airborne asbestos measurement procedures using phase contrast microscopy inherently contain several sources of error, OSHA stated that "phase contrast microscopy errors can be reduced if improved and. standardized procedures are followed, perhaps by adding requirements to the standard" (49 FR 14126). Although the Agency did not propose mandating a specific monitoring procedure at that time, the proposal discussed the desirability of adopting, verbatim or with modification, procedures recommended by the Asbestos Information Association (AIA) (Ex. 86002), Chatfield (Ex. 84-319). the British government. (Ex. 84-446). NIOSH (Ex. . 84-444). Need for Standardization of the Monitoring Method Evidence submitted to the record clearly demonstrates that the use of different sampling and analytical protocols for phase contrast microscopic analysis of asbestos concentration leads to different monitoring results, and that monitoring results can vary according to the equipment used (particularly the graticule), mounting and clearing procedures, and rules for counting fibers (Exs. 101G, 101H: Tr. 0/20, p. 13; Tr. 6/ 20, pp. 38-39; Tr. 7/6, pp. 79-81). For example, use of the AlA's recommended counting rules generally leads to lower GLEASON-000932