Assessing and controlling noise and why it matters

Noise-induced hearing loss is the most common non-fatal occupational illness among Ontario workers.

Industry award winners

Have you ever wrapped up a workday and found that you’re experiencing a high-pitched ringing in your ears or asking others to repeat themselves more often than usual? Consider: how loud was your workplace that day? Were you wearing proper hearing protection?

If your job involves operating or working around heavy machinery, pneumatic tools, or other loud equipment or vehicles, you’re almost certainly being exposed to noise levels that can permanently damage your hearing.

The way your ear turns sound waves into something that you “hear” is complex, but one of the steps involves delicate hair cells called cilia. They play a role in sending electrical signals to your brain, which are then interpreted as sounds that you recognize.

When the cilia are exposed to loud noise, they can become permanently and irreparably damaged. The damage can occur suddenly (as a result of a very loud noise such as an explosion) or with exposure over a period of time. In fact, it can happen so gradually that the consequence—noise-induced hearing loss (NIHL)—can be difficult to detect until it has become quite severe.

NIHL is the most common non-fatal occupational illness in Ontario. Since 2012, it has accounted for more than 50 per cent of non-fatal occupational illness claims accepted by the Workplace Safety and Insurance Board (WSIB).

Beyond permanent hearing loss or tinnitus (ringing in ears), excessive noise can cause mental and physical stress, reduce productivity, and interfere with communication at the workplace.

Assessing noise exposure

According to the Occupational Health and Safety Act (OHSA), employers must take all necessary steps to protect their workers from hazardous sound levels—first by modifying work practices and/or using engineering controls, and then, if noise levels cannot be acceptably reduced, by providing appropriate hearing protective devices (HPDs). The goal is to ensure that no one at a workplace is exposed to noise levels above 85 decibels (dBA).

In order to plan safe work and implement any necessary controls, employers must identify tasks and areas of the jobsite that could be dangerously loud. This can be done with an initial survey or assessment. Free apps such as the U.S. National Institute for Occupational Safety and Health’s Sound Level Meter can provide a preliminary snapshot of noise exposure at the workplace. Keep in mind a 5 to 10 dBA margin of error—and the fact that a smartphone app is no substitute for a full assessment by a qualified professional.

If a hazard is identified, IHSA Occupational Hygienist Jasmine Kalsi says that employers should refer to CSA Standard Z107.56 for measuring noise exposure levels. The standard outlines proper equipment use and testing methods, as well as who to test. Typically, assessing an individual worker’s exposure to noise involves that worker wearing a noise dosimeter during their shift. Gauging overall noise requires taking measurements throughout the workplace—especially in areas where workers need to raise their voices to be heard, can’t hear someone who is one metre away, or experience pain or ringing in the ears after exposure.

An occupational hygienist or someone who has been trained to conduct noise measurements should perform these tests. Kalsi has carried out testing for a number of IHSA member firms and adds that determining the amount of time that workers are exposed to noise is a significant part of her assessments.

“When conducting any noise measurement, it’s important to keep the duration of work shifts in mind,” she says. “The longer the shift, the lower the noise exposure limit that can be tolerated.”

Monitoring hearing health

Employers can also proactively measure the effects of noise exposure on workers through audiometric (hearing) testing. The Canadian Centre for Occupational Health and Safety (CCOHS) recommends audiometric testing for anyone who is exposed to average noise levels greater than 85 dBA throughout a full shift.

Here’s how it works. The test is conducted in a soundproof room. You put on headphones, through which a technician plays tones of varying pitch and loudness, and you indicate whether or not you can hear them. This determines a baseline level of sound that you can hear. The test is non-invasive, painless, and repeatable. Which is kind of the point: by getting tested regularly over time, any hearing loss can be detected early and steps can be taken to prevent further damage.

Audiometric testing has helped the International Brotherhood of Boilermakers take preventive action for some of its members. Blair Allin, the Boilermaker’s Canadian Health and Safety Representative, says that testing has enabled the union to equip its members with custom-made earplugs to provide the best noise reduction capacity for each worker. In addition, members who were found to have hearing loss were able to be referred to an audiology clinic for further testing and support.

Controlling the hazard

Allin says the Boilermakers hoped that offering audiometric testing would bring attention to the importance of hearing protection and early detection of hearing loss.

“It’s the responsibility of employers to be aware of decibel ratings,” he notes. “Where levels exceed allowable limits, the hierarchy of controls must be implemented to reduce the impact on workers.”

The most effective worker-protection strategy is to eliminate the hazard. Of course, at construction jobsites, busy truck yards, and various other workplaces, eliminating noise exposure is simply not possible.

The next-best option is to implement engineering controls, including:

  • Replacing noisy equipment with quieter gear
  • Removing non-essential workers from noisy areas
  • Isolating noisy areas with sound barriers
  • Isolating noisy equipment in an enclosed space

At the subsequent level of the hierarchy, administrative controls can include:

  • Implementing job rotations
  • Performing regularly scheduled preventive maintenance on equipment
  • Installing noise-related signage
  • Providing workers with training to educate them about noise levels, the risks of exposure, and controls including hearing protective devices

While wearing an HPD can reduce the level of noise a worker is exposed to, it is the last line of defence. It’s also not a one-size-fits-all solution. HPDs should be selected—by a qualified person—for each worker based on noise levels in their work environment and their duration of exposure.

It is possible to overprotect workers from noise, which can keep workers from hearing each other properly and create an unsafe work environment. On the other hand, too little protection increases the risk of permanent noise-induced hearing loss.

There are three commonly used types of earplugs, all of which must be inserted firmly into the ear canal and should be worn during the entire period of noise exposure:

  • Formable: Made of compressible foam or similar material that expands to the shape of the wearer’s ear canal.
  • Premoulded: Usually made out of plastic or silicone in a variety of shapes and sizes to fit different ear canals.
  • Custom moulded: Made for the individual worker by taking impressions of their ears.

Earmuffs are also an acceptable type of HPD. They fit over and around your ears, creating an “acoustical seal” to protect you from noise. Some models are equipped with a microphone to allow for communication with co-workers.

Employers should familiarize themselves with the benefits and drawbacks of different hearing protection devices as well as their ratings. This information and other helpful guidance can be found in CSA Standard Z94.2-14.

Once HPDs have been supplied, workers should inspect them before each use and ask for a replacement if they’re damaged.

Cut through the noise

SIGN UP for IHSA’s Basics of Hearing Protection eLearning course—available separately for workers, as well as employers, joint health and safety committee members, and health and safety representatives.

LISTEN to episodes 63 and 68 of the IHSA Safety Podcast, which discuss workplace noise exposure, testing, and noise-induced hearing loss.

CONTACT IHSA to schedule a noise assessment for your workplace.