Fireground Noise Levels Give Sound Reasons For Hearing Protection
features
Over 20 million Americans have measurable hearing losses—half of them severe hearing handicaps. Sixteen million more are exposed to on-the-job noise levels that may permanently damage their hearing. It is with the latter group, the 16 million, that this article is concerned.
The scene of an emergency is always a variable, whether it be a fire or an accident scene. Noise conditions at these areas are usually withstandable. However, it is of concern that the response of emergency vehicles and fireground activities expose fire fighters to high intensity noise levels.
We realize that hearing is one of our most precious possessions. Our auditory system is instrumental for learning, communications, safety, and pleasure. We also realize what life is like without hearing. Should we not protect our auditory system when exposed to hazardous noise levels? The perplexing problem of hearing loss is magnified by the fact that the victim is no more aware of his hearing loss than he is aware of aging.
Physical protection of the auditory system is a current concern of the National Fire Prevention and Control Administration’s Project FIRES (Firefighter’s Integrated Response Equipment System). The project is an attempt to improve the fire fighter’s protective envelope, from head to foot.
Sound is measured in two ways: frequency and intensity. Frequency, the pitch—how high, or low the sound actually measures—is expressed in cycles per second (cps). Most people can perceive pitches between 20 cps and 20,000 cps. Intensity, the loudness or softness of a noise, is expressed in units of decibels (dB). One dB is the smallest unit of sound that the average human can detect.
One interesting point to note is that the intensity of noise, as expressed in dB, will double with the increase of every six dB. As we progress in our survey, this is an important fact to remember.
Permissible noise level exposure limits have been established. These limits pertain to steady state, single level noise, and do not refer to impact noise. The permissible exposure to continuous noise must not exceed 90 dB without ear protection. Exposures to continuous noise must not exceed 115 dB regardless of any time value. As established by the Occupational Health and Safety Act of 1971, Table I illustrates allowable time exposure at various sound levels.
Field test made
To determine the noise levels to which fire fighters are exposed, a field test was conducted by Timothy Lippold, an audiologist with the Youngstown, Ohio, Hearing and Speech Center, and the author. Sound level measurements were taken on the test apparatus, a Sutphen 2000-gpm pumper powered by a 8V-71 Detroit Diesel engine with a turbocharger. Auditory warning devices included an electronic siren (dual speakers), a Q-2B mechanical siren, and dual air horns.
The sound level measurements were taken under various conditions with a Quest 215 sound level meter held at the level of the human ear. Measurements were taken at a slow meter response, interpreted as dBa, and a full energy response, interpreted as linear. The results are listed in Table II.
As the test results indicate, fire fighters responding under emergency conditions in jumpseat areas are definitely exposed to sound levels above 115 dB. The human ear should never be exposed or subjected to this high noise level without some type of protection. The use of ear plugs or ear muffs were strongly recommended by Lippold.
Protection for pump operator
Ear protection is also recommended for pump operators exposed to noise levels of 100+ dB for more than two hours. The continual droning of a diesel is a familiar annoyance to many pump operators at a fair-sized working fire. Questions may be raised concerning the communications factor between the operator’s ear and the apparatus radio. Tests have shown that ear protection devices will allow the auditory system to detect normal conversation tones while excluding background noise. Some departments equip their pump operators with earphone headsets, which provide direct radio communication while excluding background noise.
Extrication, rescue, forcible entry and ventilation are other fireground activities that produce hazardous noise levels. The use of air chisels and gasolinepowered circular saws produce noise levels of 110-120 dB. Also of consideration are other gasoline-powered tools, such as chain saws, generators and portable pumps that a fire fighter may have to use for an extended period of time.
Another fireground ear protection consideration may be a high-pressure gas line rupture. Some gas lines contain pressures up to 2000 psi. Should a fire fighter be confronted with this deafening roar, he could expect noise levels to exceed that of a jet plane (140 dB). Ear protection is a must in this situation.
Like any safety aid, the protection is of value only if the protective device is worn. As a suggestion, ear plugs can be stored in the pockets of turnout gear. Muffs can be positioned conveniently in the jumpseat area of the apparatus. It takes only a few seconds to put them on or remove them. Both types can be acquired for under $10.
Needs must be determined
It is understood that noise levels will vary from apparatus to apparatus. It is up to each fire department to establish its needs for auditory protection. Personal ear protection is the best hearing insurance. Makeshift protectors, such as cotton, paper and the like, are ineffective and can cause damage to the inner ear.
The Hearing and Speech Center advocates annual hearing screenings for all men exposed to noise levels exceeding 90 dB.
A fact that is often overlooked is that warning devices do what they are manufactured to do—make noise. Combining that fact with road and engine noise, harmful noise levels from tools and fireground situations, these noise levels can be harmful. This age of electronic sirens, diesel engines, and air chisels is a young age. We have not seen the physical effects of noise damage to the human ear due to the relative age of these devices. Be forewarned.
Let us not take the attitude that a little bit of noise is not harmful. This same attitude—not wearing self-contained breathing apparatus, not using safety goggles and the like—forms a pattern of apathy toward safety. Protect your hearing. Don’t let it become a target for noise!
