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Occupational noise isn't music to ears

By Michelle Morra-Carlisle
| www.cos-mag.com

When Dimitrio Guzzardi attended a rock concert with his spouse recently, they had great seats eight rows from the stage. They also had a good view of the person in charge of measuring sound levels. Guzzardi, an industrial hygienist, read the meter over the man’s shoulder.

“It was 120 decibels where we were sitting,” he says. “I wore hearing protection and heard the music beautifully. Everyone thought I was nuts, but my ears did not ring after the concert.”

Despite odd looks from the neighbours, Guzzardi also wears hearing protection at home when mowing the lawn, because lawnmowers typically emit a substantial 110 dB. His job as principal of Guzzardi and Associates, providers of occupational health and safety training and consulting in Chestermere, Alta., has made him hyper-aware of the fact that once hearing is lost, it is gone for good.

“Hearing loss can start at a very low decibel range,” he says. “The damage can be cumulative, and it’s also a natural part of the aging process. Why would anyone want to accelerate that?”

An insidious workplace health risk that comes on gradually, hearing loss doesn’t always get the attention it deserves. It breaks no limbs and causes no blood loss, so why care? Often, people don’t know they should care until it’s too late. With continued noise exposure, hearing deteriorates and, eventually, the loss spreads into those lower frequencies involved in speech.

Hearing protection program

In workplaces where noise exists, occupational health and safety law requires a written program to prevent hearing loss. Much more than handing out earplugs, a good hearing conservation program involves a thorough analysis of the hazard in each work environment and input from the workers.

Identify noisy jobs, noisy work areas and levels of noise. This step requires walking through the workplace, talking to employees to seek their input, and assessing the levels of noise to which they are exposed. High-tech noise measuring equipment such as dosimeters and sound lever meters are recommended.

After identifying the areas and degrees of noise, document everything. Create a floor plan that shows the location of equipment, noisy areas, where workers are stationed and noise control measures already in place. OHS law also requires signage in noisy areas to alert people they must wear hearing protection and limit their time spent in those areas.

Ontario’s Industrial Accident Prevention Association says the next step is to decide which control methods best suit the workplace.

Engineering controls. Ideally, noise control would always occur at the design stage of equipment or machines. Most often, however, employers end up finding ways to reduce the noise of existing machines. Engineering controls are by far the best way to address occupational noise but can be cost prohibitive when major plant retrofits are necessary.

Administrative controls. After engineering controls, these are the next best option. Administrative controls involve making changes to the job itself through process and procedures that limit workers’ time spent in a noisy area, finding quieter ways to do the task, rotating workers and routinely maintaining equipment so it runs as smoothly — and with as little noise — as possible.

Personal protective equipment (PPE). If, despite everyone’s best engineering and administrative efforts, the workplace is still noisy, workers must wear hearing protection.

What to wear and how to wear it are not self-explanatory. Choosing the appropriate earplugs or earmuffs for the work environment should be the responsibility of someone with qualifications in industrial hygiene, specifically in noise control.

Selecting the right hearing protection

The guidelines for hearing protection are generally consistent across all Canadian jurisdictions. According to WorkSafeBC, the two most important determining factors are noise level and comfort. Class B earmuffs or earplugs are a good choice for most workplaces but, for very noisy jobs, Class A may be more appropriate. As for comfort, it depends on the size and shape of the person’s head or ear canal and other factors.

It’s important to know the proper application of earmuffs or earplugs for better protection. Guzzardi says that for low-end frequencies of noise, earplugs are a good starting point. For any noise above 500 Hz, however, earmuffs are a better choice.

A word of caution: the degree of protection may vary from manufacturers’ claims. On the box is a noise reduction rating number. That number, Guzzardi says, was set in laboratory conditions on a test dummy and doesn’t always reflect the reality of a workplace.

The actual degree of protection, he explains, depends on what the device is made of, how well it fits the worker’s ear canal, how long the worker wears it, the noise frequency and whether the device is worn correctly.

Too much of a good thing

Silence may be golden but it’s not always safe. When selecting hearing protection for the workplace, don’t necessarily opt for the maximum protection. There are many situations where conventional earplugs or earmuffs block out too much sound. Some sounds, such as conversation and warning signals, are important to a worker’s safety.

In December 2012, three CN employees were clearing snow from tracks in northeast Edmonton when they were struck by oncoming train. They couldn’t hear the train’s whistle because they were using snowblowers and wearing hearing protection.

Education and buy-in

Another critical component to a hearing protection program is training. Contrary to popular belief, wearing protection is not straightforward. Workers must be trained in the use of earplugs, for example, many of which involve a very specific method of rolling the device, pulling back the ear, inserting the device and holding it until it fills the ear canal.

Workers and employers must also be educated on the importance of hearing protection. The ability to hear is a fragile resource not to be taken for granted.

It’s up to health and safety professionals, workers and management to instill a safety culture that says, “You have the protection. Wear it.” Aging will naturally affect hearing over time. Why speed up the process?

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