Also in 1969, the Bureau of Labor Standards promulgated an occupational construction noise standard under the Construction Safety Act, which was later adopted by OSHA in 1971. Soon after, in 1972, NIOSH published recommendations for an OSHA occupational noise standard, which included a recommended 8-hour TWA exposure limit of 85 dBA, an 80 dBA sampling threshold, and a 5-dBA exchange rate. However, in 1973, OSHA's Standards Advisory Committee maintained the 90-dBA 8-hour TWA, 90 dBA sampling threshold, and 5-dBA exchange rate. Even though noise energy exposure doubles every 3 dB, OSHA thought it important to account for the time during the workday that a worker was not exposed to noise hazards. At the time, using a 5-dB exchange rate was viewed as a sufficient way to account for this.
Estimators General Construction Man Hour Manual Pdf Free 185
While OSHA provided requirements for hearing conservation programs in general industry under the 1983 Hearing Conservation Amendment (HCA), the construction industry standard remained less specific in that regard. In 2002, an advance notice of proposed rulemaking (ANPR) was published in the Federal Register, 67:50610-50618, considering rulemaking to revise the construction noise standards to include a hearing conservation component for the construction industry that provides a similar level of protection to that afforded to workers in general industry. However, the rulemaking did not proceed and the occupational noise standard for construction remained unchanged.
Construction Industry: Noise in construction is covered under 29 CFR 1926.52, "Occupational Noise Exposure," and 29 CFR 1926.101, "Hearing Protection." Under 29 CFR 1926.52, employers are required to use feasible engineering or workplace controls when workers are exposed to noise at or above permissible noise exposures, which are listed in Table D-2 [1926.52(d)(1)]. The PEL of 90 dBA for an 8-hour TWA is measured using a 90-dBA threshold (this is the only threshold used for the construction industry noise standards). 29 CFR 1926.101 requires employers to provide hearing protectors that have been individually fitted (or determined to fit) by a competent person if it is not feasible to reduce noise exposure below permissible levels using engineering or workplace controls.
The requirements for permissible noise exposures and controls under the construction standard are the same as those under the general industry standard (1910.95), though other requirements differ. Continuing, effective hearing conservation programs are required in all cases where the sound levels exceed the values shown in Table D-2 (1926.52(d)(1)). When a hearing conservation program is required, employers must incorporate as many elements listed in the Standard Interpretation titled "Effective Hearing Conservation Program Elements for Construction Industry" (08/04/1992) into their program as feasible.
Just because a surface area vibrates, it is not correct to assume it is radiating significant noise. In fact, probably less than 5% of all vibrating panels produce sufficient airborne noise to be of concern in an occupational setting. However, vibration damping materials can be an effective retrofit for controlling resonant tones radiated by vibrating metal panels or surface areas. In addition, this application can minimize the transfer of high-frequency sound energy through a panel. The two basic damping applications are free-layer and constrained-layer damping. Free-layer damping, also known as extensional damping, consists of attaching an energy-dissipating material on one or both sides of a relatively thin metal panel. As a guide, free-layer damping works best on panels less than -inch thick. For thicker machine casings or structures, the best application is constrained-layer damping, which consists of damping material bonded to the metal surface covered by an outer metal constraining layer, forming a laminated construction. Each application can provide up to 30 dB of noise reduction.
Hearing protection devices (HPDs) are a form of PPE and are the last line of defense for protecting workers from noise exposures. They may also be used in combination with engineering and administrative controls discussed above. HPDs are generally used during the time it takes to implement engineering or administrative controls or when such controls are not feasible or when engineering controls are implemented but still do not control the noise below acceptable levels. Unless great care is taken in establishing a hearing conservation program, workers will often receive very little benefit from HPDs. The best hearing protector, when fitted correctly, is one that is accepted by the worker and worn properly. If the worker exposure is above 85 dBA (8-hour TWA), hearing protection must be made available, along with the other requirements in the hearing protection program.
When utilizing HPDs, consideration must also be given for potential interference with communication requirements at the worksite, as they may make it difficult to hear warning alarms such as equipment alarms, emergency notifications, or backup alarms on mobile equipment. In these situations, communication headsets with integrated hearing protection may be a feasible solution, as they would provide hearing protection while allowing workers to hear and communicate with others. In addition, HPD fit-testing could be utilized to determine the appropriate attenuation for a given environment, by identifying an HPD that would provide necessary attenuation to protect the hearing, but not so much that it would interfere with the ability to hear warning alarms. Special consideration may be needed for workers with pre-existing hearing loss, as use of HPDs may further interfere with their ability to hear warning signals. However, it should be noted that such workers still must be protected from exposure according to requirements under the general industry and construction noise standards, as applicable, as there is no exception for employees who have diminished capacity to hear or who have been diagnosed as deaf (see letter of interpretation, August 3, 2004).
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.
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.
The receiver (the worker) can be protected from noise by an isolation booth. In the construction industry, a common example of a personnel enclosure is the cab on heavy equipment, such as a dozer. Figure 41 shows another type of personnel enclosure (in this case, a multi-person control room). The design concepts for personnel enclosures are similar to those for equipment enclosures, but because they are used to enclose people, safe access and egress, fresh air supply, and thermal comfort are critical considerations. For any personnel enclosure, the room or booth's ability to exclude noise is impaired while the door is open. Workers are more likely to keep the door closed if they perceive that the atmosphere inside the booth is at least as comfortable as it is outside the booth. Workers generally use a personnel enclosure most effectively--keeping the door closed to exclude noise--when the enclosure provides tempered air (seasonally heated or air conditioned) and a sense of air movement inside.
Exchange rate (or doubling rate): The increase or decrease in decibels corresponding to twice (or half) the noise dose. For example, if the exchange rate is 5 dBA, 90 dBA produces twice the noise dose that 85 dBA produces (assuming that duration is constant). The OSHA exchange rate is 5 dBA (see Table D-2 of the construction noise standard, 29 CFR 1926.52, and Tables G-16 and G-16a of the general industry noise standard, 29 CFR 1910.95).
Example: A factory hires a health and safety consultant to measure the noise exposure of the workers. The consultant writes a report that states that workers are exposed to 183% Dose, according to the general industry standard, 29 CFR 1910.95. Convert this Dose into an 8-hour TWA. 2ff7e9595c
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