Solution Summary: Using Hearing Protectors
Hearing protectors - ear plugs, canal caps and ear muffs - protect the user from hearing loss due to chronic exposure to loud noises. Engineering and administratrive controls should be used to maintain an average workplace noise level below 90 dB and if possible below 85 dB. Worker noise exposure must be known or estimated. If average noise levels after using engineering and administrative controls exceed 90 dB(A), hearing protectors must be used. Hearing protectors should be used if the average noise level exceeds 85dB(A). Hearing protectors should be selected with consideration of both the noise exposure and the conditions on the job.
Hearing protectors typically provide much less protection in the field than they do in the laboratory tests used to establish the noise reduction rating (NRR) that EPA requires to appear on their packaging. OSHA recommends that the NRR be "derated" by subtracting 7 dB from the label vaulue and dividing the remainder in two. A hearing protector with an NRR of 25 under this formula would be derated to a protection level of (25db-7db)/2 or 9 dB.
It is critical that hearing protectors be properly inserted and worn, otherwise they may provide little or no protection. Follow the manufacturer's direction carefully. For foam and premolded plugs and canal caps, the outer ear should be pulled out and back with the opposite hand to straighten the ear canal. Foam plugs should be rolled down tightly with no creases, inserted fully and held for a few seconds while they expand. Premolded plugs should be fully inserted. Muffs should be placed snuggly around the ears with nothing disrupting their tight fit with the skin.
Masonry Tasks, in order of increasing average noise level
|Tasks||Average Noise Level (dBA)||Maximum Noise Level (dBA)|
|Break, Rest, Lunch||84.8||103.0|
|Manual Material Handling||89.4||105.3|
|Bricking, Blocking, Tiling||91.6||114.0|
|Grouting and Mortaring||92.9||113.7|
|Pointing, Cleaning, Caulking||95.3||115.2|
|Operating Work Vehicle||98.0||116.7|
Masonry Tools, in order of increasing average noise level
|Tools||Average Noise Level (dBA)||Maximum Noise Level (dBA)|
|Powder Actuated Tool||82.6||111.0|
|Welding & Cutting Equipment||87.1||108.5|
|Hammer, Mallet, Sledge||90.4||115.4|
|Screw Gun, Drill Motor||91.7||115.8|
|Other Hand Power Tools||95.4||118.3|
|Hand Power Saw||97.2||114.0|
|Stationary Power Tool||101.8||119.8|
Select hearing protectors to match your noise exposure
Hearing protectors have an EPA Noise Reduction Rating (NRR) that represents the noise reduction achieved under laboratory conditions. These reductions are seldom achieved in the field so OSHA recommends that NRRs be “derated”. OSHA recommends subtracting 7 dB from the NRR and then dividing that number by 2. Following OSHA’s recommendation a foam ear plug with an NRR of 33 could be relied on to provide a true reduction of 13 dB for a typical user if inserted following the manufacturer’s instructions. If both ear plugs and muffs are used, 5 dB of protection is added to the protection of the best rated protector. Higher levels of protection can be achieved if hearing protectors are carefully fitted by a qualified person and inserted by very well trained users.
|Protector||NRR||Derated NRR||Range of Use||Ear Noise Level|
|Plugs + Muffs||+5 dB||15-20||100-110||85-90|
*NIOSH recommends allowing more protection for muffs (70% of NRR-7dB) and less for pre-molded plugs (30% of NRR-7 dB)
Reduce exposure times for very high noise levels
Allowable noise exposure levels are determined for a person working an 8 hour day. If the selected hearing protection does not reduce the noise level in the ear to below 90 dB, the amount of time of noise exposure must be reduced. A reduction of 3 db of noise is allowed for each cutting of exposure time in half. Tasks such as chipping concrete inside a mixer or grinding inside a boiler expose a worker to constant noise levels of 105 dB or more. A worker doing these or other task at noise levels above120 dB(A) should use double protection and their time doing that task should be limited one hour or less per day of exposure at that level. Greater time at task may be allowed if both the noise level and hearing protection use are monitoring by a qualified person and the expected noise exposure level does not exceed 90 dB(A)
Loss of hearing due to chronic and acute noise exposure
How Risks are Reduced:
Hearing protectors reduce the amount of sound energy that enters the inner ear.
It is well established that hearing protectors can reduce the amount of noise entering the inner ear and that excessive chronic noise exposure causes hearing loss. However, the research literature is less certain about the amount of noise reduction that hearing protectors provide when worn in the field. Both OSHA and NIOSH have recommended significantly "derating" the noise reduction rating assigned to hearing protectors based upon EPA test criteria. The agencies do not agree on the details of the derating scheme.
Effects on Productivity:
Hearing protectors may also reduce work related stress by reducing irritating noises.
Warning devices and needed operations related sounds can usually be heard when moderate and lower rated hearing protectors are used. Site traffic and material handling safety plans should take noise and hearing protection into consideration when establishing rules for vehicle and material movement and warning methods. High level hearing protection should not be worn in high vehicle or material movement areas unless their use is clearly provided for in the site traffic and crane safety plans.
An annual hearing test should be conducted to determine if workers have had any loss of hearing ability. Any significant shift in the worker's hearing ability should result in a reevaluation of the hearing conservation program including worker retraining in the use of protectors.