Canadian Occupational Safety

March/April 2020

Canadian Occupational Safety (COS) magazine is the premier workplace health and safety publication in Canada. We cover a wide range of topics ranging from office to heavy industry, and from general safety management to specific workplace hazards.

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Page 15 of 35

F E A T U R E 16 TURNING DOWN THE VOLUME Excessive noise may not often be associated with industries such as health care and hospitality, but Linda Johnson reports that noise-induced hearing loss is higher than expected in these sectors MORE and more attention has been focused in recent years on the effects of noise in public spaces. When Woodstock General Hospital in Ontario opened a new facility in 2011, it built in design features — including sound- absorbing ceiling tiles and smaller nursing stations — to reduce patients' exposure to noise. Organizations provide lists of quiet restaurants free of charge. Recently, one frustrated diner developed an app with a sound meter that will let restaurant patrons measure actual noise levels when they're out for dinner. For patients and diners, excessive noise causes annoyance, stress and the inability to communicate. But too much noise can also affect workers. In fact, while hearing loss has long been considered a major hazard for workers in heavy industry, manufacturing and mining, it is proving to pose a hazard in occupations not generally associated with a high risk of hearing loss. A 2018 study by the National Institute for Occupational Safety and Health (NIOSH) in the United States looked at workers in the health-care and social assistance sector and concluded that hearing loss rates were higher than expected, given that these occupations have long been assumed to present low exposure to noise. The study found the overall prevalence of hearing loss among noise-exposed workers in the sector was 19 per cent, while it was 31 per cent in the medical and diagnostic laboratories subsector. Other high-risk sectors included: child day care services; ambulatory and health-care services; offices of some health practitioners; community food and housing services; and emergency and other relief services. A 2015 study published in the International Archives of has been associated with increased risk of cardiovascular disease, especially among workers who are already predisposed to heart problems. Determining hazardous noise levels To determine whether any amount of noise is safe, the safety manager requires two numbers: the noise level and worker exposure duration, says Alberto Behar, a professional engineer and researcher at Ryerson University in Toronto. The level is expressed in decibels, which is usually abbreviated to dB(A). (The "A" indicates the sound is measured using a special filter, called "A," which cuts low frequencies.) Generally, noise is hazardous to a worker if the noise level during an eight-hour work shift is at or above the time-weighted average of 85 dB(A), about the same as a leaf blower or a motorcycle. Exposure to this noise level over many years will result in hearing loss. "The noise level has to be within 85 decibels, and the worker has to be exposed no more than eight hours a day, or 40 hours a week, to be safe from hearing loss. That means, over the person's working life, they won't suffer hearing loss," Behar says. "What is safe also depends on anatomy. Some people can be exposed to higher noise than 85 Otorhinolaryngology said that noise levels in a hospital emergency room reached peak levels in excess of 85 dBA occurring at least once per minute from monitor alarms, overhead speakers and slamming doors. High noise levels were also reported in operating rooms, hospital kitchens, intensive care units, hospital laundry facilities and around helicopter emergency medical crews. WorkSafeBC recently issued a safety bulletin to draw attention to the risk of hearing loss for bartenders, servers and other workers in the service industry. Despite the hazard, caused largely by the use of amplified music, noise levels in pubs and nightclubs across Vancouver and Victoria routinely exceed safe limits during workers' regular shift hours. Exposure to hazardous noise can cause permanent hearing loss, as well as tinnitus (ringing or buzzing in the ears). Noise-induced hearing loss limits a person's ability to hear high-frequency sounds and understand speech. Lower noise levels, while they may not damage hearing, can still lead to such non- auditory health effects as annoyance, lack of sleep, stress, interference with speech communication, performance and behaviour, reading, memory acquisition and mental health. Though not well documented, excessive noise decibels without any problem, and some people will be exposed to less noise and they will have hearing damage." Most Canadian jurisdictions set the occupational exposure limit (OEL) for eight hours at 85 dB(A). Federal legislation sets the limit at 87 dB(A), while the limit in Quebec is 90 dB(A). When a noise level is higher than 85 decibels in a workplace, noise levels and exposure time should be reduced. Determining the revised maximum exposure time for a worker is calculated using an "exchange rate": As the sound level goes up by the amount of an exchange rate, exposure time must be halved. In Canada, the most commonly used exchange rate is three. This is largely because, based on how noise is measured, whenever a noise level rises by three decibels, the sound pressure doubles. For example, using an exchange rate of three, an employer would calculate that if the workplace sound level is 88 decibels and a worker has an eight-hour shift, then the worker's exposure time must be decreased to four hours. To determine whether there is a workplace noise hazard, safety managers should identify sources and levels of noise, the workers who are affected and exposure duration. This information will help managers determine what hearing protection they should provide to workers. If the noise level is at or above 85 decibels, employers should establish a hearing conservation program. Reducing noise hazards The first step in a hearing conservation program is to reduce the noise, says Anna Van Maanen, audiologist at WorkSafeBC. "Ideally, you do not start off with "The noise level has to be within 85 decibels, and the worker has to be exposed no more than eight hours a day, or 40 hours a week, to be safe from hearing loss." Alberto Behar, Ryerson University

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