For whom the decibel tolls
Occupational Hygiene Noise - Exposure/Exposure Limits Protective Equipment
Employees in the professional sports industry face a myriad of dangers: from being caught in the crossfire as pucks and balls go whizzing by, to dodging hulking athletes and being on the receiving end of unruly players and frustrated fans. But...
Employees in the professional sports industry face a myriad of dangers: from being caught in the crossfire as pucks and balls go whizzing by, to dodging hulking athletes and being on the receiving end of unruly players and frustrated fans. But a couple of recent studies found that it may be their ears that are bearing the brunt of the abuse.
The January issue of the Journal of Occupational and Environmental Hygiene published two articles that found the noise referees and arena staff are exposed to could be pushing the boundaries of what is considered safe.
In the first study, entitled Occupational and Recreational Noise Exposure from Indoor Arena Hockey Games, 54 personal noise dosimetry samples — of which 34 were obtained from workers inside the arena — were taken over the course of seven hockey games in two sporting arenas.
While more fans than employees were affected, researchers found that 40 and 57 per cent of workers were overexposed to noise. The exposure rate used in the study was based on the American Conference of Governmental Industrial Hygienists’ noise-exposure criterion — similar to that used in many jurisdictions in Canada.
In particular, the study found that the peak noise levels reached 124 A-weighted decibels (dBA) in one arena, compared to the 55 dBA of a normal conversation.
“Part of the problem with these sports arenas is the venues encourage crowd noise,” says William Brazile, the study’s co-author and assistant professor at the Colorado State University College of Veterinary Medicine and Biomedical Sciences in Fort Collins, Colorado. As the workers they monitored were not sitting with the crowd, they did not have people yelling right next to them, he adds.
The second study, Sports Officials’ Hearing Status: Whistle Use as a Factor Contributing to Hearing Trouble, examined hearing loss among sports officials. A survey on hearing loss and tinnitus among more than 300 referees in basketball, football, volleyball, wrestling, soccer, hockey and lacrosse found a higher prevalence of self-reported hearing problems than that observed in the general population. The noise produced by whistles can reach up to 116 dBA, which has a maximum unprotected exposure time of about five seconds.
Gael Hannan, a program specialist at the Toronto-based Hearing Foundation of Canada and director on the Canadian Hard of Hearing’s national board, says the only way to protect the hearing faculty is to avoid noise exposure. Officials can also wear hearing protection, but “they may not want to do [that] on ice, even though it probably would not interfere with the spoken language, depending on the type of earplugs they used,” she suggests.
In Canada, each jurisdiction sets its own occupational noise-limit regulations. For most areas of the country, the maximum permitted noise-exposure level for eight continuous hours is 85 dBA — about the sound of a passing diesel truck or snow blower. For every three dBA that the noise increases (known as the exchange rate), the amount of time a worker can be exposed is halved.
Not all jurisdictions ascribe to the 85/3 scale. Federally, the maximum eight-hour exposure level is 87 dBA; in the Northwest Territories, the exchange rate is five. In Quebec, the maximum exposure level is 90 dBA with an exchange rate of five, while in Nunavut, the exchange rate is three for mining and five for workplaces in general. “You can probably tell if someplace is noisy if you have to raise your voice,” says Marc Cousineau, provincial hygienist with the Ontario Ministry of Labour in Toronto.
Continuous exposure to loud noises is not the only way to harm your ears. An extremely loud crash or a cannon explosion, as Brazile found, can cause instantaneous damage. “[At] one stadium in particular, they would actually fire a cannon periodically during the game. People were exposed not only to continuous noise, but to this very, very high impulse noise that was well above the 140 dB exposure limit.”
Researchers measured the noise level of the cannon from about six metres away. At that arena, however, spectators were allowed within two metres of the cannon. “At six metres away, we recorded a level of 151 dB,” Brazile notes.
Alberta, Saskatchewan, Manitoba, Ontario, Prince Edward Island and Newfoundland and Labrador have not set any limit for this type of impulse and impact noise, while other jurisdictions have a maximum peak pressure level of 140 dBA.
These risks are present in many jobs that take place in areas usually reserved for leisure activities and entertainment, such as bars and concert venues. However, these places of employment are not typically the first that spring to mind when it comes to protecting against occupational hearing loss.
Unlike industrial manufacturing warehouses and machine and woodworking shops, sports arenas are not generally regarded as noisy workplaces. As such, the volume levels inside an arena may not even be something that many sports officials take into consideration.
Cousineau says in his 13 years of working with the ministry, he cannot recall a single instance when he was called to an arena to investigate a noise complaint. “It’s not that we wouldn’t go and investigate noise in a sports arena; it’s just that to my understanding, we haven’t had any.”
Brazile reports that during the course of his research, he has not come across a worker who was wearing hearing protection. “I don’t think they are aware that they are overexposing their ears,” he says.
Bill Hodgetts, associate professor of speech, pathology and audiology at the University of Alberta in Edmonton, says there are two types of tiny hair cells in the human ear: the inner hair cell sends signals to the brain while the outer hair cell is most affected by noise.
“When the noise reaches a certain level for a certain amount of time, the outer hair cells have hair-like things on top of them that will lay down, which actually makes the hair cell non-functional,” he explains.
Hodgetts has conducted research on noise exposure at hockey arenas, specifically during Stanley Cup games. He found that fans were showing signs of temporary hearing loss after the game.
“If you just have a one-time exposure and you’re a fan and go to one game, chances are that after about 16 hours or so, that will go away and things will go back to normal,” he says. “If you keep having exposures like that, where you are there every night and you keep experiencing some minor damage or what we call a temporary threshold shift, then it will become a permanent threshold shift.”
Workers need to be aware that noise exposure does not end when they leave their workplaces. Employees who hold jobs that expose them to high levels of noise should take protective measures both before and after their work hours. “Going to a movie is not going to cause permanent damage, because you’re not sitting in there for eight hours listening. But it’s not just the two hours in a movie theatre — it is everything else that’s going on in your life,” Hannan contends.
For employees who do not usually work in a noisy environment, the problem of temporary hearing loss is less of a concern. “If you have someone in the workplace for 40 years, that’s another story,” Cousineau says.
One thing is clear — the noise level to which people are exposed at work and outside work hours is a serious issue. Noise-induced hearing loss is now the number-one cause of hearing loss, edging out aging, Hannan reports.
“It’s such an easy fix,” Brazile says. “People just have to bring a pair of earplugs, which would significantly reduce that noise. But people don’t do it for concerts or sporting events. It’s such simple, cheap protection.”
While ear protection can dim the volume of everything going on around a worke
r by at least 15 dBA, it should not hinder his or her job functions, Hodgetts notes. However, hearing damage does not have an immediate effect and is less visible than other physical injuries. As such, getting workers to wear ear protection in jobs that are not traditionally seen as being at risk can be a tough sell.
Hodgetts says everyone wears safety goggles when they are running the table saw, but no one puts in earplugs. “And the reason is the ears don’t bleed,” he suggests. “People don’t pay attention to the damage that happens to their ears.”
Greg Burchell is former assistant editor of CANADIAN OCCUPATIONAL HEALTH AND SAFETY NEWS.
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