‘What did you say?’ Understanding the risk of hearing loss among firefighters
Detailing the connection between noise and disease – and what firefighters can do to better protect their hearing
Recently, I wrote about portable gas meters to remind firefighters and officers that their PPE must include more than their structural firefighting ensemble. I’m going to continue in that vein with this piece about another important, albeit smaller, piece of PPE: hearing protection.
Most emergency scenes are pretty high-intensity when it comes to loud noises (operating fire apparatus, gas-powered equipment, radio traffic, etc.). By now, most firefighters and officers should be informed and educated about the risks to their hearing, so why don't more firefighters and officers use the appropriate protective gear?
I've written before about how firefighters can protect their hearing, but let’s now consider a different approach to the hearing issue – one focused on your physical and mental health.
Studies show the negative impact of noise on our physical health. One study determined that traffic noise is associated with an increased risk of on our bodies, including our cardiovascular and metabolic health, while another showed that living and working in noisy areas, such as cities or near highways, increased the frequency of strokes by 30%. Conversely, living and working in quieter areas reduced stroke frequency by 25%.
Emergency scenes certainly qualify as noisy environments. So do fire stations where personnel are exposed round-the-clock to noise from radio traffic, dispatch tones and alert sounds, not to mention the operation of fire apparatus and portable gas-powered equipment during training, inspections and maintenance.
THE CONNECTION BETWEEN NOISE AND DISEASE
When you're exposed to an incessantly noisy environment, your brain’s amygdala is stimulated. The amygdala regulates our stress response, commonly referred to as “fight, flight or freeze” (FFF).
When stimulated by noise, the amygdala signals your cardiovascular system to increase blood pressure while shunting blood flow to organs (such as those in your intestinal tract) that aren’t essential for a FFF response. At the same time, more blood flows to the muscles of the back and extremities.
The amygdala also signals the adrenal glands to start pumping cortisol – a stress-related hormone – into your system. Increased blood pressure and cortisol levels have been linked to heart attacks and strokes, especially when those increased levels were present on a regular basis because the amygdala is constantly being stimulated. In “Fight, Flight, Freeze: What This Response Means,” Kirsten Nunez provides examples how the amygdala’s activation of the FFF response affects your body:
- Heart rate. Your heart beats faster to send oxygen to your major muscles. In freezing temperatures, your heart rate might increase or decrease.
- Lungs. Your breathing speeds up to deliver more oxygen to your blood. In the freeze response, you might hold your breath or restrict breathing.
- Eyes. Your peripheral vision increases so you can better notice your surroundings. Your pupils dilate and let in more light, which helps you see better.
- Ears. Your hearing becomes sharper.
- Blood. Blood thickens, which increases clotting factors. This prepares your body for injury.
- Skin. Your skin might produce more sweat or get cold. You may look pale or have goosebumps.
- Hands and feet. As blood flow increases to your major muscles, your hands and feet might get cold.
- Pain perception. Fight-or-flight temporarily reduces your perception of pain.
The American Heart Association warns that individuals routinely exposed to high levels of noise face an increased risk of heart attack. Sound familiar?
NOISE AND ITS IMPACT ON THE BRAIN
Damage to your hearing can be both acute (from one significant insult, such as an explosion) or chronic (from continuous exposure, such as working in a noisy environment without hearing protection). According to Dr. Douglas Hildrew, medical director for the Yale Hearing and Balance Program, noise damages the critical hair cells within the cochlea, resulting in hearing loss that can affect your cognitive functions.
Not being able to hear normally can result in declining levels of cognitive functions that can cause a person to begin isolating socially out of frustration or embarrassment. They might then find themselves lacking sufficient mental stimulation or social interaction, thus increasing the likelihood of more cognitive decline.
Both mental stimulation and social interaction are critical factors for maintaining good health and functionality in all the other parts of the brain. When the amygdala is constantly being stimulated, it begins to grow larger and other parts of the brain will begin to atrophy.
This should serve as a warning for firefighters as we consider the negative impact that social isolation has on our mental health, which mental health professionals say can contribute to depression, substance abuse and even suicide.
HOW MUCH NOISE IS TOO MUCH NOISE?
The amount of on-the-job noise exposure is most accurately measured using a noise dosimeter that’s worn during an entire, or part of, a tour of duty. The NIOSH Sound Level Meter (SLM) app (available for iOS) was developed to help workers make informed decisions about their noise environment and promote better hearing health and prevention efforts.
According to OSHA, excessive noise is exposure to 85 decibels or more of noise during an eight-hour period. OSHA Action Level requires all employees exposed to this level of noise to wear hearing protection that meets the ANSI S3.19-1974 testing of Noise Reduction Rating (NRR) levels.
In all cases where the sound levels exceed the values shown in Figure 1, a continual effective hearing conservation program should be followed.
In Figure 2, you can see the exposure levels used by OSHA and some examples of the noise generators that produce those noise levels. OSHA strongly recommends wearing hearing protection when in any of the environments that produce sounds at levels higher than 85 decibels.
While it's not practical to eliminate noise in our lives, we can take steps to protect our hearing by taking the following actions.
GET A BASELINE HEARING TEST
According to Hearingloss.com, one in five Americans experience hearing loss, and 80% do nothing about it, typically because hearing loss occurs gradually. Interestingly, most people will get an eye exam on a regular basis, but very few have regularly scheduled hearing tests. Several years ago, I took a free online hearing assessment that indicated I had some hearing loss. I wrote about what I did after that in “Firefighter Gets Fitted for Hearing.” Take the next step and make an annual hearing assessment part of your ongoing health maintenance program.
I can’t stress enough the importance of knowing where you stand with your sense of hearing. My hearing professional told me that hearing loss for high-frequency sounds, such as birds chirping or people enunciating sounds for the letters F, S or TH, can be treated successfully. But when people lose the ability to hear lower-frequency sounds, there’s nothing to be done. Even hearing aids cannot help that kind of loss.
USE ACTIVE HEARING PROTECTION
Active hearing protection involves wearing noise-reducing equipment like earmuffs or ear plugs. Keep in mind that the level of noise is based on the NRR rating of the protection device being used. While the NRR is measured in decibels, the hearing protection you choose does not reduce the surrounding decibel level by the exact number of decibels associated with that device’s NRR.
For example, if you’re operating a pumper where the level of noise exposure is 100 decibels and you are wearing earplugs with an NRR 33dB, your level of exposure would not be reduced to 67 decibels (100 minus 33 decibels).
To determine the actual amount of decibel deduction applied (when decibels are measured dBA, which is the most common), you would use the NRR number for the earplugs, subtract seven, then divide by two.
For the earplugs you’re using in this scenario, your actual noise reduction equation would look like the following: (33-7)/2 = 13. Subtract 13 decibels from 100 decibels and your level of noise exposure would be reduced to 87 decibels.
Here are some of the most used types of active hearing protection equipment:
- Communication system headsets: Most fire departments have been become proactive in protecting their firefighters from the noise created by today’s fire apparatus by installing noise-canceling radio headsets.
- Multi-position earmuffs: Most earmuffs available today are lightweight and can be worn over the head, behind the neck, or under the chin.
- Earplugs: Simple noise-reducing earplugs are an inexpensive hearing protection option. Here are a few suggestions.
- Christmas tree-shaped ear plugs: These reduce the overall level of sound, but still allow the full sonic spectrum to get through to your ears, unlike foam earplugs that can overly mute those high-frequency sounds.
- Silicone earplugs: These are remarkably effective for blocking noise or loud music. To use, you roll them into a small cylinder shape and gently insert them into the outer ear, allowing the silicone material to expand and shape itself to fit.
- Foam earplugs: These can be bought in bulk, which makes them convenient for one-time use.
Also, check out this Hearing Protection Calculator that estimates the sound or noise level when wearing hearing protection.
PROTECT YOUR HEARING AWAY FROM THE JOB
Hearing conservation should also be part of everyday living. Here are some hearing conservation strategies for everyday use, especially if you routinely listen to music through headphones or ear buds:
- Use active noise-canceling (ANC) headphones: ANC employs microphones that monitor the ambient noise around you, then use integrated electronics to cancel out those external noises. All you hear is the sound you want to hear, like the music playing in your headphones. Another benefit is that you can listen to that music at a lower volume because outside noise is eliminated.
- Get earbuds that use a combination of ANC and passive noise canceling (PNC) technology: The ANC cancels out the unwanted ambient noise while the PNC more effectively seals the ear canal to block outside noise.
- Install Ear Machine on your phone: If you’re already experiencing some hearing loss, this app (available for iOS and Android) turns your phone into a hearing device by amplifying frequencies you don't hear well and feeding them to your ears via your earbuds.
By taking charge of your own hearing conservation, you’ll protect not only your sense of hearing but your physical and mental health during and after your fire service days.