November/December 2011
Noise-level assessment, engineered noise-reduction strategies, regular hearing tests, and—yes—personal protective equipment are all part of a comprehensive hearing-protection program.
By Diana Mota
Hearing loss is not like other workplace injuries, says Steve Forystek, director of health, safety, environment, and transportation for PSC Metals (Cleveland). “Burn yourself with acid, and you know immediately” that you need medical attention, he points out. But you can’t tell by looking that someone’s hearing is being harmed. Although occupational-noise-induced hearing loss is common, typically it’s painless and develops gradually over a long period, making it easy to miss, notes Brad Witt, director of hearing conservation for Howard Leight (San Diego), a manufacturer of industrial hearing protection. After spending time in a noisy environment without hearing protection, you might notice an immediate hearing loss. Once the noise stops or you leave the noisy area, it could take seconds, minutes, or days for your hearing nerves to recover. If the noise is severe enough, however, it causes some permanent damage, and the damage accumulates. The longer and more frequent your exposure, the longer it takes your hearing to recover—until, one day, it doesn’t. (Short exposures to extremely loud noises are equally harmful.) In the early stages, this damage affects a person’s ability to understand speech, Witt says. As it progresses, it affects the ability to hear all sounds. Many people unconsciously adapt: They watch people’s lips as they speak, or they turn up the volume on the radio or television. But undiagnosed, untreated hearing loss can result in a progressive loss of communication, socialization, and responsiveness to the environment.
How big of a problem is this? Noise, or unwanted sound, is one of the most common health problems in U.S. workplaces, according to the Occupational Safety and Health Administration (Washington, D.C.). About 22 million U.S. workers are exposed to hazardous noise levels every day at work, and about 8 million of them suffer from noise-induced hearing loss, according to estimates from the National Institute for Occupational Safety and Health (Cincinnati), a federal agency that conducts research on work-related injury and illness and makes recommendations on how to prevent them. One out of four workers will develop permanent hearing loss because of occupational exposure at current limits, it reports.
Occupational noise can affect a person’s quality of life in other ways as well, says Deanna Meinke, associate professor of audiology and speech-language at the University of Northern Colorado (Greeley, Colo.) and a NIOSH consultant. Workers exposed to noise might complain of irritability, sleeping problems, or fatigue. Excessive noise exposure can lower job performance and lead to high rates of absenteeism. It can decrease accuracy and interfere with concentration, which can contribute to accidents, and the heightened stress levels it can create can lead to other health problems, such as heart, stomach, and nervous disorders, according to OSHA’s website.
The equipment and materials at recycling facilities can produce some ear-ringing sounds. To protect workers’ hearing, you’ll need to do more than just hand out earplugs. Scrapyards can work to prevent occupational hearing loss by assessing whether they have a noise hazard problem and, if so, by implementing a hearing-conservation program that assesses and monitors hearing hazards, reduces noise at the source, and provides free annual hearing exams, hearing protection, training, and motivation for workers. It’s the right thing to do, and it’s also the law: OSHA requires an effective hearing conservation program when workplace noise levels reach a time-weighted average of 85 decibels or more over an eight-hour shift. (Even noise below that level can present a safety hazard, NIOSH points out, if it interferes with communication or a worker’s ability to hear warning signals.) Companies that don’t comply potentially face citations, fines, and higher insurance premiums due to employee hearing damage.
Assessing Noise Exposure
Before deciding how best to control a facility’s noise, you must identify its noise hazards—and workers who are exposed to them—through noise monitoring or sampling. It’s a good idea to conduct such assessments whenever the facility significantly changes operational procedures or equipment, says Rick Hare, safety director of Consolidated Scrap Resources (York, Pa.) and chair of the ReMA Safety & Environmental Council. Noise sampling should represent typical production cycles and all work processes, he adds.
A safe noise level depends on two factors: the level or volume of the noise and the length of time workers are exposed to it, says David Byrne, a NIOSH research audiologist. You’re checking not only for whether noise exposure reaches an average of 85 dB over 8 hours, the level at which OSHA requires a company to have a hearing conservation program and provide hearing protection, but also for whether noise levels reach a time-weighted average of 90 dB or more, the point at which OSHA requires workers to use hearing protection. The time-weighted average takes into account the intensity of the noise and the duration of exposure. The louder the noise, the shorter the exposure that’s allowed, Byrne says. According to the OSHA standard, for every 5 dB increase in the noise level, the allowable duration is cut in half. For example, “an exposure of eight hours at 90 dB, four hours at 95 dB, or two hours at 100 dB would cause a worker to reach the maximum daily dose.” NIOSH recommends a more cautious standard, however, by cutting the allowable duration in half for every 3 dB increase in noise above 85 dB, Byrne says.
Scrap companies can use various methods and equipment to determine if a facility has a noise problem. Here’s a simple initial test: Stand at arm’s length from a co-worker and try to speak to one another. If you must shout to communicate, the noise level is too high. Facilities can accurately measure noise levels that remain consistent with a sound-level meter, says Joe Bateman, ISRI’s safety outreach manager. Measure each source of noise separately, he says— “that includes vehicles.” PSC Metals purchases noise-testing equipment and trains its personnel to perform the tests; other companies, such as Consolidated Scrap Resources, hire an outside firm to do it. Using the meter, the tester walks around the facility and surveys for noise hazards. The results can be plotted on a “noise map,” which shows measurements for the different work areas. “We use that information to create a road map for how to address noise,” Forystek says.
The easiest way to determine how long a worker is exposed to excessive noise is to have that person wear a dosimeter, which measures sound and computes the time-weighted average, during his or her regular shift, Byrne says. Some dosimeters attach to workers’ clothing, with a microphone placed near an ear, while newer technology is worn in the ear. These devices are a good choice for workers who move from area to area, Byrne says. Employers don’t have to test every worker at a facility; they can use the results from one employee to represent all workers with similar noise exposures. Companies can use more sophisticated acoustical equipment, such as octave-band analyzers and sound-level recorders, to assess their options for engineering noise controls, according to NIOSH’s publication Preventing Occupational Hearing Loss: A Practical Guide. Each company should document its procedures for evaluating noise, including when and how often it tests and how it takes measurements, selects samples, records data, calibrates instruments, and reports results, the NIOSH guide says. It recommends reporting test results to the head of the hearing-conservation program and to employees (in summary form during hearing-protection training, for example) as well as recording the results of area measurements or noise exposure dosimeters in each employee’s medical record.
Controlling Noise
Unfortunately, companies with noise problems often turn first to hearing protection—earplugs—not noise control, say both Byrne and Bateman. “PPE should be the last resort,” Bateman says. “We are required to try and eliminate or reduce these hazards before we just stick people in earplugs.” Earplugs also are the least effective form of noise control, Byrne says, because the hazardous noise still exists, and many people use them incorrectly. “Recyclers should start by asking themselves, ‘What have I done to reduce the hazards?’” Bateman says. For example, make operating noise a consideration in the purchase of new equipment, Byrne suggests. With existing equipment, look for ways to deaden the sound through engineered solutions. NIOSH recommends consulting with engineering, safety, and industrial hygiene personnel as well as with the employees who operate and maintain the equipment when developing a noise-control plan. An acoustical consultant can help design, implement, and evaluate such controls. Look for ways to insulate the equipment, absorb sound, or dampen or isolate vibrations with vibration pads, enclosures, barriers, or other methods.
The movement of metal scrap can be a major source of noise for metal-processing yards. “You don’t want metal bouncing off of metal,” Forystek says. PSC Metals lines bins used to collect metal scrap that falls from conveyor belts with rubber. “It’s been extremely effective,” he says. Also try to reduce the height from which material falls, Byrne adds. Forystek also recommends using acoustical panels on the walls and ceilings of picking stations to absorb noise. Some recyclers have completely enclosed equipment such as shredders, with workers operating the equipment from outside the enclosure or remotely. Even without enclosing the equipment, increasing the distance between equipment and workers can help, Meinke says. Routine maintenance, such as replacing worn or defective parts, also can help mitigate noise. This includes maintaining the engineered noise solutions: An equipment enclosure is only effective if it’s kept closed and the seals are in good condition, the NIOSH guide states.
If engineered solutions aren’t sufficient or economically feasible, another approach NIOSH recommends is to review operating procedures and work schedules. Rotate workers out of noisy areas more frequently, or provide extended quiet breaks. The risk, however, is that such approaches just expose more workers to high noise levels, the agency points out. If these approaches don’t succeed in reducing or eliminating the noise problem, only then should a facility turn to hearing protection via personal protective equipment.
Hearing Protection
All three principal types of hearing protection—earplugs, ear bands, and earmuffs—are designed to prevent excessive noise from reaching the inner ear, Witt says. Within those categories are more than 400 types of devices, Meinke says. She recommends that employers offer several options because the best device is one the employee will wear comfortably and use correctly and that works with other PPE he or she has to wear.
If hearing protection isn’t worn correctly, it’s worthless, these experts caution. In some cases, workers might not have enough protection; in other cases, they might have too much. Byrne worries about the latter. “Most industrial noise exposures are 95 dB or less,” he says. According to the NIOSH guide, the ideal hearing protector brings hazardous noise levels to the 70 to 85 dB range. Thus, “you really only need about 10 dB of noise reduction [from] your hearing protectors,” Byrne says, but many products come with noise-reduction ratings of about 30 dB. “If you wear them correctly, you could actually cause [safety problems] by not hearing warning signals or other people talking that you need to hear over the protector.” Think of hearing protection like sunglasses, he says: Sunglasses block some types of light from reaching your eyes, but “they don’t make you blind.” Likewise, workers should still be able to hear when wearing hearing protection. Witt echoes that concern. The No. 1 reason workers say they remove hearing protection is because they can’t hear when they need to hear, he points out. Removing the devices even for just a few minutes can negate their effect. Further, employees who already have some hearing loss are more susceptible to overprotection, he says. At the other end of the scale, it’s possible that individual off-the-shelf products don’t provide enough protection. When sound levels exceed 100 dB, for example,workers might need to wear earplugs and muffs together, Byrne says.
Earplugs are comfortable for extended use, and when used correctly, they block out noise effectively, Witt says. But good hygiene is essential, he warns. “You have to make sure your hands are clean before inserting them.” Workers should dispose of single-use earplugs daily and clean multiple-use earplugs with mild soap and water and dry them thoroughly between uses. Inspect reusable earplugs for dirt, cracks, or hardness, and replace them if they’re damaged. Earplugs should sit well inside the ear canal and not stick out. Witt suggests one way to tell if they’re installed correctly: If you cup your hands over your ears and then release them, you shouldn’t hear a significant noise difference.
Ear bands are convenient for intermittent noise, Witt says. Workers can keep them around their necks when they’re not in use. They typically don’t control noise as well as earplugs, he points out, because the band itself can act as an amplifier. Workers should clean and replace the pods regularly and not overstretch the band.
Earmuffs “generally reach the ratings on the package because not much can go wrong with putting them on,” Witt says. Some workers complain that they feel hot and heavy when worn for extended periods, however. Wearers should clean the ear cushions and headband regularly with mild soap and water and replace ear cushions and foam inserts every four to six months with normal wear, more often with heavy use. They also shouldn’t overstretch the headband. Some versions are designed to attach to hard hats; others have electronic circuitry to amplify certain sounds, such as human voices or warning signals, and cut off when noise reaches hazardous levels.
With all three types of hearing protection, effectiveness depends on a good seal between the skin’s surface and the surface of the ear protector. Throughout the day, workers might need to reseat the devices if they become loose from activity such as talking. NIOSH suggests reducing the expected performance of hearing-protection devices to account for user error: 25 percent for muffs, 50 percent for formable plugs, and 70 percent for other plugs.
Audiometric Testing
An employee’s annual audiogram often is the first indicator of whether he or she has adequate hearing protection, Byrne says. Regular hearing tests, or audiometric evaluations, can help catch noise-induced hearing loss in its early stages, motivate employees to wear their hearing protection correctly, and measure the effectiveness of a company’s hearing-conservation program.
Each employee who will be exposed to excessive noise should receive a hearing test before he or she begins work in a noise-hazardous area for the first time. The test serves as a baseline measurement for future tests. Testing employees who aren’t exposed to high noise levels is also a good idea, Meinke says. The two employee groups should essentially show the same results if the hearing loss prevention program is effective. Hare and Forystek also advocate a widespread testing approach. “Because we don’t want to pick and choose, we test everyone except the drivers,” Hare says. (Drivers’ hearing gets evaluated during the biannual physical they must undergo to get or maintain a commercial driver’s license.) “Hearing, unfortunately, is something you don’t get back” once you lose it, Forystek says, so to be safe, the company monitors the hearing of all of its employees.
Employers can outsource audiometric testing to mobile testing contractors or local hearing clinics, though larger companies might find it cost-effective to purchase the equipment and train an employee to perform the testing under the supervision of an audiologist or qualified physician. The company should use the same type of audiometer—if not the same instrument—from year to year and ensure it’s properly calibrated and used in a sound-treated room, the NIOSH guide advises. The agency recommends performing audiometric examinations toward the end of an employee’s work shift. “In the early stages of noise-induced hearing loss, noise exposure causes temporary shifts in hearing threshold level, which, if repeated on a regular basis, become permanent,” it says. “By testing toward the end of the workday, rather than before or early into the workday, these temporary threshold shifts can be identified, and steps can be taken to counteract them [to] prevent subsequent, permanent hearing loss.”
NIOSH also recommends having previous test results available so that if the current test detects a shift in hearing ability, an immediate retest can take place. “It’s estimated that as many as 70 percent of all audiograms showing a shift will be resolved if the earphones are refitted, the employee is reinstructed, and a retest is administered at the time of the initial test,” the NIOSH guide states. If the shift in hearing ability remains, however, the employee should undergo a retest within 30 days. “Give that person’s ears a chance to recover,” Byrne says. “Do the repeat test after [the worker is] not exposed to noise for a while to make sure it’s a true shift.” If it is, a health professional will need to determine whether it was work-related. “There are hundreds of reasons a person could lose hearing,” Byrne points out, “and one of them is [workplace] noise exposure.” If the medical professionals determine the hearing loss is work-related, employers must report it on the OSHA 300 log, Bateman says. OSHA compliance officers will investigate whether the company has complied with every section of the hearing-conservation standard.
How much of a shift in hearing test results should trigger additional testing and follow-up? “OSHA uses the term Standard Threshold Shift to describe an average change in hearing … of 10 dB or more [from the baseline levels] for the frequencies of 2,000, 3,000, and 4,000 Hz,” the NIOSH guide reports. If such a shift occurs in one or both ears, OSHA recommends retesting within 30 days. If the second test confirms the shift, OSHA considers that a recordable injury. (In addition to reporting that result, the company should revise the employee’s baseline to reflect the new measurement.) NIOSH recommends a slightly different action level, which it calls a significant threshold shift: “a change of 15 dB or more [from baseline levels] at any frequency 500 through 6,000 Hz … that is present on an immediate retest in the same ear and at the same frequency.” It recommends a confirmation test within 30 days preceded by a quiet period of at least 14 days.
Byrne points out that it’s now feasible to test the effectiveness of a worker’s hearing-protection devices. Until recently, such tests “required a lab setting, but now there are laptop computer-based systems” employers can use on site, he says. Most of the systems can test whether the worker is wearing earplugs correctly and how much sound they’re blocking; a few also can test the efficacy of earmuffs, he says.
The routine audiogram also provides an opportunity for one-on-one employee training, which should review the health effects of noise, the purpose of hearing protectors, the types and advantages of different devices, as well as selection, proper fit, use, and maintenance. “Training is probably the most important part of a hearing conservation program, both for employees and management,” Meinke says. “Everyone from the front-line worker to the CEO of the company must recognize the importance of hearing and understand the ways and means of protecting it.” A commitment to hearing protection evolves via high-quality training in both group and one-on-one formats, she adds. Employers should offer information about protecting ears while off the job and make hearing protection available for workers to take home, Meinke says. Forystek agrees. “Preventing hearing loss is a 24/7 effort.” It doesn’t end when employees go home, he says. It’s possible to prevent hearing loss, Forystek points out, but it’s “something you have to work at continuously.”
Diana Mota is associate editor of Scrap.
Noise-level assessment, engineered noise-reduction strategies, regular hearing tests, and—yes—personal protective equipment are all part of a comprehensive hearing-protection program.