Occupational Noise Exposure The effects of noise on hearing; Hearing protection – purpose, types and use; The purpose of audiometric testing and how it works; and Your right to see noise measurement records and hearing test results. This presentation will cover the following topics:
Occupational Noise Exposure Noise, or unwanted sound, is one of the most common health problems in American workplaces. The National Institute for Occupational Safety and Health (NIOSH) estimates that 30 million workers in the U.S. are exposed to hazardous noise.
Exposure to high levels of noise may cause hearing loss, create physical and psychological stress, reduce productivity, interfere with communication, and contribute to accidents and injuries by making it difficult to hear warning signals. Effects of Exposure to Loud Noise
Exposure to loud noise will inevitably cause hearing loss over time. Loud noise damages or destroys the hair cells in the inner ear. Another effect can be “tinnitus” or permanent ringing in the ear.
Long Term Exposure to Noise Our ears can recover from short exposure to loud noise, but over time nerve damage will occur. The longer and louder the noise, the greater chance permanent damage will occur. There is really no such thing as “tough ears” or “getting used to it”.
Effects of noise to inner ear Normal hair cells Noise-damaged hair cells Hair cells in the inner ear transmit noise signals to the brain.
Hearing loss from noise exposure is usually not noticed because it is so gradual. Usually a person loses the ability to hear higher pitches first. Often the first noticeable effect is difficulty in hearing speech. Hearing Loss From Noise Exposure
Tinnitus From Noise Exposure Exposure to high noise levels can also cause permanent ringing in the ear or “tinnitus”. Tinnitus sufferers usually complain of constant whistling, squealing, roaring or buzzing in one or both ears. Severe tinnitus may disrupt sleep, reduce concentration and cause irritability and depression.
When is Noise Too Loud? Noise is measured in units called “decibels” or “dB” If two people 3 feet apart must shout to be heard, the background noise is too loud (above 85 decibels). Noise above 140 decibels causes pain and immediate hearing loss (e.g. gunshots).
What is Too Much Noise Exposure? Damage from noise exposure depends on the loudness and length of exposure. Scientific studies have shown that hearing loss can occur when 8-hour average noise exposure exceeds 85 decibels.
What is Too Much Noise Exposure? The risk of hearing loss increases dramatically as noise levels increase. Exposure to noise levels above 115 decibels for even five minutes is very risky. Impact or banging noise above 140 decibels will cause immediate damage to nerves in the ear.
Daily Allowable Exposure Times to Noise The table below shows noise levels and how long a person can be exposed without hearing protection before there is damage to the ear. Noise LevelAllowable Exposure Time 85 decibels8 hours 90 decibels4 hours 100 decibels1 hour 105 decibels30 minutes 110 decibels15 minutes 115 decibels0 minutes
OSHA Noise Exposure Limits Permissible Exposure Limit (PEL) There is a level that cannot be legally exceeded. This is called the “permissible exposure limit” or PEL. For an 8-hour Time- weighted Average (TWA): no more than 90 decibels. OSHA has established noise exposure standards in order to protect the hearing of employees.
OSHA uses a 5 dB exchange rate for the decibel scale. The exchange rate means that increasing the noise level by 5 dB doubles the loudness. For example, 90 dBA is twice as loud as 85 dBA. Twice as loud OSHA Noise Exposure Limits Exchange Rate
When the amount of noise exposure is above the “action level” of 85 dBA, employers are required to implement a hearing conservation program that includes the following: - Conduct periodic noise monitoring - Provide annual audiometric testing - Provide training The Action Level is 50% of the permissible exposure limit (PEL). OSHA Noise Exposure Limits Action Level
Hearing Conservation Program
UNC-CH Hearing Conservation Program The purpose of the Hearing Conservation Program is to provide for the protection of University employees from long term hearing loss associated with noise levels in the workplace in compliance with OSHA Standard 29 CFR Part Occupational Noise Exposure.
All University employees whose noise exposures equal or exceeds an 8-hour time weighted average (TWA) of 85 decibels are enrolled in a hearing conservation program (HCP). Environment, Health and Safety (EHS) administers the HCP for the University. The program includes: Periodic monitoring of noise exposures Annual training on noise exposures Use of hearing protection Annual audiometric (hearing) testing UNC-CH Hearing Conservation Program
Current program participants: Chilled Water Systems Cogeneration Systems Department of Laboratory Animal Medicine- Animal Care Technicians Finley Golf Course Maintenance Department Public Safety Grounds Department Construction Masonry Shop UNC-CH Hearing Conservation Program
EHS conducts noise surveys and personal monitoring to identify areas or activities where noise exposure may exceed the action level. The following slides present noise data for departments enrolled in the HCP. Noisy Areas & Equipment at UNC-CH
Chilled Water Systems Chilled Water Systems employees are exposed to noise generated by the mechanical equipment used to provide chilled water to the campus. The chillers and pump motors generate the higher noise levels. Row of chillers at the South Annex Plant Row of pumps at the South Plant
Chilled Water Noise Survey Summary This table displays the minimum and maximum noise levels measured during a survey of four Chilled Water plants. Chilled Water employees should wear hearing protection when working in the plants to help prevent occupational noise-induced hearing loss. PlantMinimum dBAMaximum dBA Cobb South Annex South East
Cogeneration Systems Cogeneration Systems employees are exposed to noise generated by the mechanical equipment used to provide steam to the campus. The coal crushers and the turbine generator create the higher noise levels. Coal crusher Housing for the turbine generator
Cogeneration Systems Fuel handling employees are exposed to the highest noise levels from the railcar shaker. The railcar shaker produces approximately 112 dBA. The action level is exceeded after 15 minutes of exposure at this level during a 10 hour shift. Employees should remain in the control room during the operation of the shaker to reduce noise exposure. Coal railcars
Division of Laboratory Animal Medicine (DLAM) The Division of Laboratory Animal Medicine (DLAM) is responsible for the care of all vertebrate animals on the UNC-CH campus. DLAM animal care technicians are exposed to noise levels that can reach up to 104 dBA when caring for some of the larger animals. Technicians must wear hearing protection when handling the animals.
Finley Golf Course The equipment used by the Finley Golf Course Maintenance Department to maintain the course produces high noise levels as shown below. EquipmentSound Level in dBA Grand Master 3000-D86.0 Reel Master 6500-D89.0 Toro Speed Roller (Salsco)96.5 Toro Multi Pro Suzuki M 120X99.5 Toro Side Winder (Reel Master 3100-D) 90.0
Public Safety UNC Public Safety police officers are exposed to noise levels that reach up to 111 dBA near the student risers during basketball games. The firearms used during annual training/qualifications can exceed 140 dBA.
Grounds Department EquipmentSound Level dBA Chain Saw (Stihl)106.7 Edger (weed eater)104.0 Bush Cutter (Stihl)103.5 Leaf Blower (Stihl)102.7 Lawn Mower (Toro, riding)98.0 Seeder (Lesco)95.5 Lawn Mower (Scag, walk behind)95.0 Tractor (Ford 3930)94.4 Generator (Honda)93.0 Lawn Mower (Jacobsen, riding)92.7 Aerator (Ryan)92.0 Lawn Mower (Honda, walk behind)92.0 Lawn Mower (Ransoms, riding)92.0 Forklift (Caterpillar)90.8 Lawn Mower (Toro, walk behind)90.4 Lawn Mower (John Deere, riding)90.2 Tiller (Honda)89.5 Bluebird Seeder (Honda)88.0 Bed Edger (Honda)85.9 Gator (John Deere)83.5 The Grounds Department has over 60 employees, each an expert in various aspects of landscape design and maintenance, irrigation, tree care, and vehicle maintenance. Here are some of the equipment commonly used by employees to maintain the campus landscape and their respective noise levels as measured by EHS.
Masonry Department EHS monitored a UNC Masonry employee while the employee used a jackhammer. The noise levels reached 106 dBA. The University of Washington has conducted research on the noise levels of tools used by masonry workers.
Hierarchy of Noise Control Employers must first implement feasible engineering or administrative controls when employees are subjected to sound exceeding the PEL (90 dBA for an 8-hr TWA). If such controls fail to reduce sound levels below the PEL, hearing protection must be provided and used to reduce sound levels below the PEL. Engineering controls involve modifying the noise source so it is quieter. Administrative practices may include shift rotation or exposure limitation.
Hearing Protection Hearing protection devices (HPDs) are considered the last option to control exposures to noise. Employers must make HPDs available to all employees exposed at or above the action level. Employees must wear HPDs when exposed at or above the PEL. HPDs must be provided at no cost to employees and must be replaced as necessary.
There are three types of hearing protection – ear muffs, earplugs and ear caps. Ear muffs and earplugs provide about equal protection, ear caps somewhat less. Types of Hearing Protection earmuffs earplugsear caps
All hearing protectors are designed to reduce the intensity (loudness) of noise to the inner ear. They work much better than wads of cotton or bits of cloth stuffed in the ear. All three types have advantages and disadvantages and people vary on which they prefer to use. Types of Hearing Protectors Cotton doesn’t work!!
Earplugs are made of foam, rubber or plastic and are either one-size- fits-all or in sizes small, medium and large. Some are disposable, some are reusable. They are lightweight, and require no maintenance. They are inserted into the ear canal. Hearing Protection – Ear Plugs
Some people may find ear plugs uncomfortable to wear for long periods at first. Ear plugs rarely cause infection or prolonged irritation of the ear canal. Most people can find a comfortable fit by trying several different sizes, types or brands. Custom-molded earplugs can be obtained for maximum comfort. Ear Plug Comfort custom molded earplugs
Foam type earplugs are one-size-fits-all and must be inserted properly into the ear. Inserting Foam Earplugs Roll earplug into a small cylinder first, then insert in ear while pulling the ear upwards and outwards. Click here to watch a 5-minute video on fitting foam earplugs.Click here
Checking the Fit of Foam Earplugs To check if foam earplugs are fitted properly press firmly cupped hands over your ears while listening to a steady noise. With properly fitted plugs the noise levels should be about the same whether or not the ears are covered.
Premolded Earplugs Premolded earplugs are reusable and made of rubber or plastic. To check if premolded earplugs are fitted properly gently tug on the stem of the inserted earplug. Then, gently move the stem in and out. With properly fitted plugs you should feel slight pressure on your eardrum. This technique is called the tug and pump test. For safe removal, carefully twist the plug to break the seal.
Ear muffs cover the whole ear and are preferred by some people. They have replaceable pads and some high-tech styles filter out specific noise pitches. They last longer than most plugs. Ear Muffs
Some muffs are attached to hard hats or goggles. Some high-tech muffs can filter out certain frequencies or have radios inside for communication in high noise areas. Attached Earmuffs
Muffs can be uncomfortable in hot weather. Muffs don’t seal well for someone with glasses or heavy sideburns. Ear Muff Comfort & Glasses
Ear caps are like earplugs, except they do not go into the ear canal, they only block it. They are good for occasional use or for people who find earplugs uncomfortable. They are not as protective as earplugs or muffs. Ear Caps
The “noise reduction rating” or “NRR” of hearing protection is measured in decibels. The NRR is found on the earmuff or earplug package. The higher the number, the greater the protection. The NRR is determined in a laboratory. The NRR must be adjusted for workplace conditions. Noise Reduction of Hearing Protection
Using earmuffs or plugs in noisy areas can actually make it easier to hear coworkers or machinery. They reduce overwhelming loud background noise. They are similar to dark glasses that reduce the sun’s glare making it easier to see. How can you hear anything with earmuffs on?
Earmuffs and plugs provide good protection only when used properly. Sometimes people will remove hearing protection for “just a minute” in a noisy area. In areas of very high noise exposure, this could result in noise overexposure. Proper Use of Hearing Protection It won’t protect your ears if it is around your neck!!!
It takes just a few minutes of unprotected exposure at noise above 115 decibels to risk hearing damage. Earplugs not well inserted into the ear canal will not provide complete protection. Likewise, earmuffs not snug against the head will “leak” noise into the ear. Proper Use of Hearing Protection
Hearing aids do not block out enough sound for most workplace noise. Some hearing aids can actually increase the noise level at the ear. Just turning off the hearing aids will not prevent further hearing loss from noise exposure. Hearing Aids Are Not Hearing Protection
Portable Radios/CD Players/iPods These devices do not provide protection from noise. The earphones are not earmuffs and the music only adds to background noise. The music level in the earphones themselves can exceed 85 decibels and cause hearing loss.
“Audiometric testing” is the same thing as hearing tests. It is done by trained technicians to detect any hearing loss. Audiometric testing is required for any employees enrolled in the HCP. What is Audiometric Testing?
Most of us develop a mild hearing loss as we age, especially in the higher pitches. A severe or significant hearing loss at a younger age may mean you have had excessive noise exposure. Audiometric testing done yearly can detect early stages of hearing loss. Purpose of Audiometric Testing
Audiometric Testing Audiometric testing results can be used to check the following: If the hearing protection in use is adequate, If there is a change in noise exposure, If there is a medical condition of the ear unrelated to noise exposure.
When you are first hired, a baseline test is taken. The testing is repeated every year after that and compared to the baseline test result. If a hearing loss is detected, you will be referred to a doctor or audiologist. How Does Audiometric Testing Work?
Audiometric Testing Audiometric testing produces printed audiograms which show hearing ability at several pitches or frequencies. These frequencies include those of the human voice. The second and following year tests are compared to the first year tests or baseline. If there is hearing loss of 10 decibels or more in the human voice frequencies, you will be sent to the doctor or audiologist.
What is a Standard Threshold Shift? A Standard Threshold Shift (STS) is an average hearing loss of 10 decibels or more in the human voice frequencies of 2000, 3000, and 4000 hertz. Employees identified as having a STS are required to obtain an additional audiometric test within 30 days. The retest will verify if the shift is temporary or permanent.
An audiogram is a printed chart of the results of the hearing test. They look similar to the results below. What is an Audiogram?
Noise Measurement Records & Hearing Test Results Employees have the right to see noise measurement records and get copies of their hearing test results. Contact EHS for access to previous noise measurement records and audiometric testing results. Obtain current audiometric test results during annual audiometric testing.
UNC-CH EHS would like to acknowledge the Washington State Department of Labor & Industries for providing portions of the training content.