General Industry: 29 CFR 1910.95, \"Occupational Noise Exposure.\" This standard is designed to protect general industry workers, such as those working in the manufacturing, utilities, and service sectors. The general industry standard establishes permissible noise exposures, requires the use of engineering and administrative controls, and sets out the requirements of a hearing conservation program. Paragraphs (c) through (n) of the general industry standard do not apply to the oil and gas well-drilling and servicing operations; however, paragraphs (a) and (b) do apply.
For compressed air systems that perform a service or specific task, such as ejecting parts or blowing off debris, a number of devices are available for retrofit at the point of discharge. Another typical application for compressed air is in blow-off guns or air wands. These tools come in a variety of sizes and shapes, and depending on the velocity of the air and the surface area they contact, can generate noise levels of 90 dBA to 115 dBA, depending on the velocity of the air and the surface area they contact. It is recommended that the Noise and Vibration Control Product Manufacturer Guide be consulted for a list of available suppliers. Usually, the manufacturer websites provide sufficient information and self-help guidance to enable selection of the most appropriate device for retrofit.
There might also be opportunities to replace equipment with different devices or materials. Here, the user should investigate whether alternative and quieter ways exist to accomplish the task or intended service. Where practical, examples of source substitution include:
OSHA's CTC is qualified to perform periodic (annual) calibration for the noise-monitoring instruments and acoustical calibrators commonly issued to CSHOs. CTC also coordinates periodic factory calibration of any OSHA-owned noise-monitoring instruments that it does not service directly.
During periodic calibration, the CTC also performs preventive maintenance to ensure that the equipment remains fully functional over its life expectancy. If the calibration team detects a problem, it services the instrument as necessary. When returning equipment to CTC for periodic calibration, be sure to include a note about any problems or concerns with equipment function so they can be evaluated as part of the maintenance process. If equipment is not functioning as expected, CTC requests that the instrument be returned for inspection, even if it is not yet due for calibration.
Confirm that you understand the procedures for calibrating each of the instruments you use. If in doubt, review instructions in each instrument's user's manual and consult CTC if questions arise. In general, as long as the sound level readout is within 0.2 dB of the known source (the calibrator output), it is suggested that no calibration adjustments be made. If large fluctuations (greater than 1 dB) in the level occur, then either the calibrator or the instrument may have a problem.
Additionally, confirm that you know how to change or charge the battery in both the calibrator and the instruments. If in doubt, review instructions in each instrument's user's manual. A low battery is the number-one cause of equipment failing pre- and post-use calibration. Changing the battery will often bring the equipment back into an acceptable calibration range immediately, but a little practice is needed to change the battery quickly on some equipment. Most rechargeable batteries cannot be changed in the field so it is even more important their charge status is known and changed as necessary prior to instrument usage. Rechargeable batteries that can no longer be recharged must be replaced by CTC or the manufacturer. Be prepared, so that a low battery doesn't slow you down during an early morning calibration session (Figure 15).
Whether detachable or integrated into a sound level meter, an octave band analyzer receives its daily calibration in conjunction with the sound level meter with which it will be used. This might involve activating an additional setting during the daily meter calibration. Consult the user's manual for the equipment you will be using.
Some octave band analyzers can be set to automatic function (i.e., the instrument automatically checks the sound level of each frequency band and stores the results). Other instruments require the user to manually switch between the different frequency bands, recording each reading in sequence.
When monitoring is complete at the end of the day, follow standard procedures for recording results from the instruments. If necessary, consult the instrument user's manual or contact CTC for assistance. Dosimeter output usually includes the TWA (normalized to 8 hours), the LAVG or LEQ representing the average dose for the period monitored, the percent dose, and the maximum or peak reading. Do not neglect to perform the post-use calibration check on each instrument.
Assumption 13: If outside or consulting engineering services are required to design and fine tune the control, then these costs must be estimated and added to Table H.1-2 values. For cost estimation, the hourly rate for a consulting acoustical engineer is assumed to be $150 (2010 dollars). The daily rate is assumed to be $1,000. Assume that the consulting engineer is local, and therefore, no travel or per diem costs need be considered. For each day in the field, it is customary for a consulting engineer to charge one additional day for report/plan preparation.
The equipment manufacturer, contacted by phone, indicates that one engineering option is to rebuild the drive mechanism and replace the cutters with those of a helical design. According to the manufacturer's technical representative, this will greatly improve the quality of the planed finish and reduce the noise level to about 90 dBA. With the existing administrative controls, everybody's daily exposure level would be reduced to less than 84 dBA. A call to the regional service technician produced a cost figure of $10,000 per planer to retrofit, with no maintenance or production penalty involved.
Costs per worker are sometimes lower for a large-scale hearing conservation program with many workers than for a small program covering just a few people. This \"economy of scale\" may reduce the per-worker cost under some circumstances, such as when a fixed daily-rate service can serve many workers in one day versus serving just a few workers for the same daily fee. Worker geography is a primary reason an employer might encounter this situation.
The worksheet results were quite consistent in showing that, using these 18 points as cost criteria, the majority of organizations spent $350 to $400 per year per worker in the hearing conservation program. Results for a few organizations, however, were substantially higher. The highest costs tended to be associated with fixed daily fees for services provided at multiple remote locations where few workers were employed (the highest hearing conservation program cost reported was $1,800 per worker per year). Costs were lower when these fixed fees, such as for mobile audiometry van service to remote facilities, could be averaged over a larger number of workers. However, in general, the total hearing conservation program cost was not notably different for small organizations compared with large organizations.
Audiograms may be recorded as a graph, in table format, or on a paper ticket. The key frequencies for review are 2,000, 3,000, and 4,000 Hz in each ear. Results should be evaluated for each ear separately; a threshold shift can occur in one ear and not the other. There are smartphone applications that will automatically calculate STS values and perform age correction. If a smart phone application is used during an investigation, some manual calculations should also be conducted to verify the application is correctly calculating STS values.
Plus, when equipment is maintained in good working order, from a noise exposure standpoint the added benefit is that it will minimize the time workers need to spend in the direct sound field of the machine while performing any service requirements.
Efforts to regulate occupational noise in the United States began about 1955. The military was first to establish such regulations for members of the Armed Forces [U.S. Air Force 1956]. Under the Walsh-Healey Public Contracts Act of 1936, as amended, safety and health standards had been issued that contained references to excessive noise; however, they prescribed neither limits nor acknowledged the occupational hearing loss problem. A later regulation under this act [41 CFR 50B204.10], promulgated in 1969, defined noise limits that were applicable only to those firms having supply contracts with the U.S. Government greater than $10,000; similar limits were made applicable to work under Federal service contracts of $2,500 or more under the Service Contract Act. The noise rule in the Walsh-Healey Act regulations was adopted under the Federal Coal Mine Health and Safety Act of 1969 (Public Law 91-173) for underground and surface coal mine operations.
No single method or process exists for measuring occupational noise. Hearing safety and health professionals can use a variety of instruments to measure noise and can choose from a variety of instruments and software to analyze their measurements. The choice of a particular instrument and approach for measuring and analyzing occupational noise depends on many factors, not the least of which will be the purpose for the measurement and the environment in which the measurement will be made. In general, measurement methods should conform to the American National Standard Measurement of Occupational Noise Exposure, ANSI S12.19-1997 [ANSI 1996a]. However, it is beyond the scope of this document to serve as a manual for operating equipment and making sound measurements. Rather, this chapter will be limited to concise remarks relevant to ope