Hearing conservation programs are programs implemented to reduce the risk of hearing loss due to hazardous noise exposure, if implemented correctly. Hearing conservation programs require knowledge about risk factors such as noise and ototoxicity, hearing, hearing loss, protective measures to prevent hearing loss at home, in school, at work, in the military and, and at social/recreational events, and legislative requirements. Regarding occupational exposures to noise, a hearing conservation program is required by the Occupational Safety and Health Administration (OSHA) "whenever employee noise exposures equal or exceed an 8-hour time-weighted average sound level (TWA) of 85 decibels (dB) measured on the A scale (slow response) or, equivalently, a dose of fifty percent." This 8-hour time-weighted average is known as an exposure action value. While the Mine Safety and Health Administration (MSHA) also requires a hearing conservation program, MSHA does not require a written hearing conservation program. MSHA's hearing conservation program requirement can be found in 30 CFR § 62.150, and is very similar to the OSHA hearing conservation program requirements. Therefore, only the OSHA standard 29 CFR 1910.95 will be discussed in detail. According to Alice Sater, employers are not implementing these programs effectively, personal protective equipment does not protect workers well, and the risk of hearing loss is not reduced.
Program requirements The OSHA standard contains a series of program requirements.
Engineering Controls: 29 CFR 1910.95(b)(1) requires that "feasible administrative or engineering controls shall be utilized. If such controls fail to reduce sound levels...personal protective equipment shall be provided and used to reduce sound levels..." Noise Monitoring: 29 CFR 1910.95(d) requires that monitoring be conducted when "any employee's exposure may equal or exceed an 8-hour time-weighted average of 85 decibels. Audiometric Testing: 29 CFR 1910.95(g) requires an "audiometric testing program" for "all employees whose exposures equal or exceed an 8-hour time-weighted average of 85 decibels". Hearing Protectors: 29 CFR 1910.95(i) states that "employers shall make hearing protectors available to all employees exposed to an 8-hour time-weighted average of 85 decibels or greater at no cost to the employees" Training: 29 CFR 1910.95(k) mandates an annual "training program" for "all employees who are exposed to noise at or above an 8-hour time-weighted average of 85 decibels..." and mandates certain aspects of the training that must be included. This includes the effects of noise on hearing; purpose, advantages, disadvantages, and attenuation of different types of hearing protectors; purpose audiometric testing. Record Keeping: 29 CFR 1910.95(m) states that employers "shall maintain an accurate record of all employee exposure measurements..."
Sound survey A sound survey is often completed to determine areas of potential high noise exposure. A noise screening is completed initially to determine which areas are higher than 80 dB A. For these areas, an official sound survey will take place. This type of survey is normally completed using a sound level meter (SLM). A sound level meter takes a measurement of the sound present in the environment at that moment. There are three types of sound level meters. Type 0 is a precision instrument normally used in laboratories. Type 1 is for precision measurements taken in the field. Type 2 sound level meters are less precise than type 1 and are often used to take all-purpose sound level measurements. There are also noise dosimeters that are worn on the body and measure the amount of noise exposure an individual receives over a given time period. OSHA guidelines state that either a SLM or noise dosimeter may be used for sound monitoring. Surveys must be repeated when there are significant changes in machinery and/or processes that would affect the noise level.
Engineering and administrative controls Engineering controls and administrative controls are ranked as the most effective protection from noise in the hierarchy of controls. Engineering controls are measures taken to reduce the intensity of noise at the source or between the source and a person exposed to the noise. This can be done by choosing tools that make less noise, installing a barrier between the worker and the noise, enclosing the machinery all together, or making sure the machinery is maintained properly (lubricating equipment). Administrative controls are limitations around noise sources that limit length of noise exposure. Some known methods are running loud equipment when less workers are present, controlling the amount of time a worker is allowed around the noise source, constructing areas that allow employees a chance to escape from the noise (a sound proof room to give recovery time), or increasing the distance between the worker and the excessive noise source.
Hearing protection devices
If engineering controls fail to maintain an 8-hour time-weighted average below 85 dBA, then a hearing protection device (HPD) is required. There are two general types of HPDs: earplugs and earmuffs. Each one has its own benefits and drawbacks. The selection of the proper HPD to be worn is commonly done by an industrial hygienist so that the proper amount of noise protection is worn. OSHA requires that HPD be given free of charge.
Earplugs There are four general classes of earplugs. These include: pre-molded, formable, custom molded and semi-insert.
Premolded earplugs do not require the plug to be formed before it is inserted into the ear. This prevents the plugs from becoming soiled before insertion. Formable earplugs are made of a variety of substances; however, all each substance shares the common feature of being able to be shaped by the user prior to insertion. One drawback of this is the obvious need for the user to have clean hands while shaping the earplug. They do have the advantage of forming to the users ear, while many premolded earplugs do not accomplish this very well. Custom molded ear plugs are unique for each person, since they are cast from each user's own ear canals. Therefore, they provide a personalized fit for each individual. Semi-inserts are generally a soft earplug on the end of band. The band aides in maintaining the earplug in position. They are often useful since they can be quickly removed and inserted.
Earmuffs
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