Occupational Hearing Hazards

Those of us who have worked in manufacturing know just how loud it can get. Machines that pound metal or shake sand out of freshly cast iron can throw off some very high dBA (decibels A-weighted, a unit for measuring ambient sound levels). Most of us are familiar with the kind of sound that is painful to hear; the kind of sound that makes us wince and cover our ears immediately. But noise-induced hearing loss (NIHL) can be caused even by sounds that are not at such extreme levels. The maximum safe level of ambient sound is about 70 dBA, and when it gets to 85 dBA (about the volume of a gas-powered lawn mower) it is considered dangerous, especially in cases of prolonged and/or frequent exposure.

Determining Noise Levels

If you need to raise your voice to talk to someone who is only 3 feet away from you, it’s likely that you are experiencing ambient noise in excess of 85 dBA. If you hear ringing in your ears and/or have trouble hearing when you leave work, even if your hearing seems fine again the next morning, it’s likely your hearing is being permanently damaged. The National Institute for Occupational Safety and Health (NIOSH) provides a great resource in the form of a free, downloadable app for the iPhone that measures sound pressure levels. It should be calibrated, but it is then accurate to within 2 dBA using the iPhone’s internal microphone. States in the U.S. differ on their requirements for employers in dealing with noise levels. Here are requirements for Massachusetts. If the noise levels in your workplace regularly meet or exceed 85 dBA, you may have some legal recourse.

Chemicals that Can Cause Hearing Loss

Some workplaces may contain chemicals that possess a degree of ototoxicity, which means they damage the ears. Certain pharmaceuticals, solvents and pesticides can be ototoxic. Many workplaces that utilize these types of chemicals can be the very same places that have a higher level of noise on the floor. The combination of damaging noise levels and ototoxic chemicals is, of course, worse than just one or the other of these risk factors. With some chemicals, the damage to your hearing will be magnified by ambient noise; that is, even levels of sound that might not cause hearing loss on their own, when combined with these chemicals, will cause greater hearing loss than the chemical by itself. Consult the Safety Data Sheets (SDS) for your workplace to find out which chemicals are risk factors in your environment, and then check to see if they are ototoxic.

Workplace Noise Can Damage More than Your Ears

Noisy environments are more stressful than we might realize. Workplace accidents can happen because warning signals or shouts go unheard, but there is a less apparent risk to noise, as well: fatigue. In a noisy environment, our brains are constantly trying to sift through the noise to make sense of what’s going on around us. This brain activity is fatiguing, akin to multitasking. While fatigued from this noise onslaught, we can make mistakes. And in the kind of environment where safety is a prime concern, some mistakes can be very costly.

And it’s not just the risk of accidents that increases with noise. Recent NIOSH investigations have found a possible link between high levels of workplace noise and increased cardiovascular risks like high blood pressure and high cholesterol.

While the risk of hearing loss has been well-known for a long time and most employers dutifully provide earplugs, these less-obvious risks are turning heads about what can be done to reduce noise in the workplace.

Reducing Noise in the Workplace

There are two approaches to noise reduction in the workplace: engineering and administrating. Engineering practices include using quieter machines, keeping machines well-lubricated, and isolating machines from workers with noise obstructions like walls or thick curtains.

Administrative practices might be scheduling noisy processes when there are fewer workers on the floor, creating quiet spaces for workers to take breaks, limiting the time a worker spends in a noisy area, or keeping workers at a distance from noise sources. Every doubling of the distance between a person and a noise source reduces the effective sound level by 6 dBA.

Hearing Conservation Programs

Employers can develop a Hearing Conservation Program in accordance with OSHA guidelines. A few requirements include measuring noise levels on the floor; providing protection, training, and yearly hearing tests; and evaluating the success of the program at reducing hearing loss. OSHA’s research has indicated that workplaces with Hearing Conservation Programs have higher productivity and lower absenteeism, leading many employers to voluntarily put them in place.