OccuSafe Industrial Hygiene Consulting

Continuous exposure to noise, 85 dBA or higher over an 8-hour shift, is considered hazardous and can cause damage to hearing. OSHA defines continuous noise as lasting 1 second or higher. Employees whose exposure exceeds these limits must participate in a facility hearing conservation program which includes annual training in noise induced hearing loss and use of hearing protectors, a written program, and baseline and annual audiograms.
 
Employees may also be exposed to impact or peak noise which is defined as sudden, high-intensity sound. Examples include hammering, explosions, and stamping. Sources include nail guns, and riveters, metal on metal impacts. OSHA has a limit of 140 dB for noise exposure and defines peak noise as anything higher. When exposed to impacts, at first it stuns the hair cells in the cochlea, but after repeated exposure can cause permanent damage. OSHA requires that employees who exceed the 140 dB limit, are provided with hearing protection and all applicable training.

Exposure to impact noise can cause the following:

• Permanent Threshold Shift (PTS): Permanent hearing loss, particularly at high frequencies, caused by damaged ear receptors.
• Tinnitus: A persistent ringing, buzzing, or humming in the ears.
• Hyperacusis: Reduced tolerance to normal environmental sounds.
• Temporary Threshold Shift (TTS): Temporary hearing loss or “plugged” ears following exposure.

Exposure to impact noise can also have non-auditory effects:

• Cardiovascular System: Increased heart rate, hypertension (high blood pressure), and increased risk of cardiovascular disease.
• Stress Responses: Increased secretion of adrenaline and cortisol, causing irritability, fatigue, and headaches.
• Cognitive and Psychological Effects: Reduced concentration, impaired speech communication, annoyance, and increased risk of mental health issues.
• Sleep Disturbance: While often occurring during work hours, loud noise can impact sleep hygiene, especially for shift workers.

The harmful effects of exposure to impact noise can be reduced or eliminated by some of the following steps:
·      Engineering Controls:Installing sound dampening materials or choosing quieter machinery and tools.
·      Administrative Controls:Limiting the time workers are exposed to loud noise.
·      Personal Protective Equipment (PPE):Proper use of earplugs or earmuffs to reduce noise exposure.

Identifying impact noise exposure can be done as part of a noise survey and may involve the use of sound level meter or a noise dosimeter. Both instruments can identify and record sounds that exceed the for 140dBA.

Hearing is so often taken for granted. Consistent or impact type noise at high levels can severely affect the ability to hear. Noise exposure can and will cause permanent significant hearing loss that cannot be recovered. Employers and employees should recognize and evaluate noise exposure and take all necessary steps to control it.