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Safety in the Woodlot: Chainsaw Hearing Protection
Is your hearing protection up to standard? Anyone who has ever used a chainsaw knows that they are loud. How many times have you heard a slight “ringing” sensation in your ears after turning off your saw? Perhaps this is an indication that the hearing protection you are using is inadequate.
Table 1 provides a comparison of several familiar sounds that most of us can relate to in relationship to the noise generated by a chainsaw. Occupational health and safety standards in Ontario mandates (see Permissible Noise Standards) that hearing protection must be worn when the workplace noise level exceeds 85 decibels (dB). As Table 1 shows, the noise level generated by a chainsaw (~104 – 106 dB) far exceeds the provincial permissible noise level. Even the newer saws that are much quieter may injure your hearing with constant exposure, thus making it necessary to wear hearing protection.
So, is your hearing protection up to standard? The following information will provide you with some guidelines in selecting and using the most suitable hearing protection for your situation.
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| It is important to recognize that sound intensity doubles every 3 dB, increases tenfold per 10 dB, and increases 100-fold per 20 dB. Photo: A. Corlett |
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Types of Hearing Protection
Earplugs – are available as formable earplugs (reusable or disposable foam plugs) that expand when inserted into the ear or as pre-moulded earplugs. Earplugs are less expensive than earmuffs. They are more comfortable in warmer weather, small and easily carried and can be used in conjunction with other personal safety equipment such as earmuffs. However, earplugs should not be used when workplace dB levels exceed 105. They must be fitted correctly to ensure adequate protection and they may irritate the ear canal. They also require more time to put on.
Earmuffs – are available in different models, with a variety of headbands and earpieces. Earmuffs are easier to fit because the various models are usually designed to fit most head sizes. They are also more durable than earplugs and usually provide greater protection when fitted properly. However, earmuffs are heavier and usually more expensive than earplugs and less comfortable when worn in warmer weather. They may also interfere with wearing of safety glasses.
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| Table 1: Examples of Sound Pressure Levels (dB) |
| Jet engine (distance 75 ft.) |
140
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| Levels at which short-term exposure may cause permanent damage |
140
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| Chainsaw |
~104 – 106
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| Circular saw |
105
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| Tractor |
96
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| Lawnmower |
90
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| Levels at which sustained exposure may result in hearing loss |
90 – 95
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| City traffic |
85
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| Ringing telephone |
80
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| Normal conversation |
60
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| Whisper |
30
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Noise Reduction Ratings (NRR)
When purchasing any hearing protection, look for the manufacturer’s noise reduction rating label (NRR). The NRR indicates the reduction in decibels that the equipment will provide. For example, earmuffs with a NRR rating of 31dB will reduce the noise level of a chainsaw from 106 dB to 75 dB.
However, it is important to note that the noise reduction ratings are based on laboratory conditions and when used in the workplace there will be some reduction in their effectiveness (e.g., if the hearing protectors are not fitted correctly or have leakage due to the user wearing glasses).
To allow for these factors, the National Institute of Occupational Health and Safety (NIOH) recommends reducing the NRR rating of hearing protection equipment as follows:
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- Earmuffs – subtract 25% from the manufacturer’s labeled NRR;
- Formable earplugs – subtract 50% from the manufacturer’s labeled NRR; and
- All other earplugs – subtract 70% from the manufacturer’s labeled NRR.
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For example, earmuffs with an NRR rating of 31 dB would be derated to 23 dB, thus reducing the chainsaw noise level from 106 dB to 83 dB. This would allow a maximum permissible noise exposure limit of about four hours (see below) per day.
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Permissible Noise Standards
As a guideline, woodlot owners may want to follow the standards outlined in the Occupational Health and Safety Act (Regulation 851) for industrial workers (i.e., loggers) where the daily maximum permissible noise exposure limit for an eight hour period is 85 dB with a 3 dB exchange rate (e.g., every increase of 3 dB reduces the permissible hours of exposure – four hours exposure at 88 dB, two hours exposure at 91 dB and one hour exposure at 94 dB).
Summary
The simple fact is – you can only lose your hearing once! So why not take the necessary steps to protect your ears by using the appropriate hearing protection. Remember the key factors in protecting your hearing are: the NRR rating of the hearing protection equipment, the dB level generated by the equipment being used and knowing the maximum noise exposure limits before damage may occur.
Additional Resources
Additional information on selecting and maintaining hearing protection equipment can be found in the followings resources.
“Hearing Protection”, Canadian Centre of Occupational Health and Safety. <http://www.ccohs.ca/oshanswers/prevention/ppe/ear_prot.html?print>
“Hearing protection: it only sounds difficult”, The Log, Ontario Forestry Safety Workplace Association. <http://www.ofswa.on.ca/>
Hazard Factsheet #4: Occupational Noise”. National Transit Institute, Rutgers University. <http://www.ntionline.com/documents/NTI_36300_f_sheet_noise.pdf>
This article was featured in a past edition of the S&W Report, the newsletter of the Ontario Woodlot Association.
© Ontario Woodlot Association, 2010
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