OSHA's Approach to Noise Exposure in Construction
|
|
Occupational Safety
and Health Administration, Directorate
of Construction
The following
was presented, in part, at the Construction Safety Council's
13th Annual Construction Safety Conference & Exposition,
February 2003, in Rosemont, Illinois |
Objectives
- Provide
technical information on construction noise and hearing conservation
- Explain
current expectations
- Review
8/5/2002 OSHA Hearing Conservation for Construction Workers Advance
Notice of Proposed Rulemaking
- Sell you
on this program so you can sell to management and employees
Presentation Outline
- Construction Noise Levels
- Noise-Induced Hearing Loss
- Prevention
- Noise Measurements
- Hearing Protectors
- Audiometric Testing
- Noise Control
- Current and Future OSHA Standards
- Benefits of Hearing Conservation Programs
Current OSHA Standards
- 1926.52 Occupational Noise Exposure
- TABLE D-2 - PERMISSIBLE NOISE EXPOSURES
Duration
per day, hours |
Sound
Level dBA slow response |
8 |
90 |
6 |
92 |
4 |
95 |
3 |
97 |
2 |
100 |
1
1/2 |
102 |
1 |
105 |
1/2 |
110 |
1/4
or less |
115 |
Sound Pressure Level
- Pressure
wave traveling in air or water
- Expressed
in decibels (dB)
- It
is the perceived loudness
- Analogy:
surface wave made when you throw a stone into a calm pool of water
- Logarithmic
scale
- Small dB
increase represents large increase in sound energy.
- 3 dB increase
is a doubling of sound energy
- 10 dB increase
represents a 10-fold increase
- 20 dB increase
represents a 100-fold increase
Noise Levels forCommon
Tools
Task/Tool
Source: NIOSH
Construction
Noise Levels
Pneumatic
chip hammer |
103-113 |
Crane |
90-96 |
Jackhammer
|
102-111 |
Hammer |
87-95 |
Concrete
joint cutter |
99-102 |
Gradeall |
87-94 |
Skilsaw
|
88-102 |
Front-end
loader |
86-94 |
Stud
welder |
101 |
Backhoe |
84-93 |
Bulldozer
|
93-96 |
Garbage
disposal (at 3 ft.) |
80 |
Earth
Tamper |
90-96 |
Vacuum
cleaner |
70 |
Source: CPWR – Center for Construction Research and Training
Source: Construction Safety Association of Ontario
Source: Construction Safety Association of Ontario
Average Daily
Noise Exposure Levels (8-hour TWA) of Heavy Equipment and Associated
Laborers(adapted
from Legris and Poulin, 1998)
Operator
and Task |
Range
in dBA |
Heavy-duty
bulldozer |
97-107 |
Vibrating
road roller |
91-104 |
Light-duty
bulldozer |
93-101 |
Asphalt
road roller |
85-103 |
Laborers
|
78-107 |
Crawler
crane < 35 ton (non-insulated cab) |
93-101 |
Crawler
crane >35 ton (non-insulated cab)
Crawler crane >35 ton (insulated cab)
|
90-98
80-89 |
Rubber-tired
crane >35 ton (non-insulated cab)
Rubber-tired crane >35 ton (insulated cab) |
78-90
59-87 |
Tower
Crane |
70-76 |
Source: NIOSH
Presumed Noise
LevelsBritish Columbia Standard
Presumes specific construction occupations are routinely overexposed
to noise
- Carpenters
- Plumber pipefitters
- Sprinkler installers
- Mobile equipment oprs
- Welders/fabricators
- Sandblasters
- Drillers
- Electricians
- Steel erectors
- Concrete workers (pumps, vibrators, jackhammers)
- Drywallers shooting tracks or boarding
OSHA Inspection
Data
- Chipping Concrete Floor
96 dBA (TWA) at 4.5 hours
Source: OSHA Madison case file
- Abrasive Blasting with Sponge-Jet Material
105 dBA (TWA) at 6 hours
(3.5 X PEL for silica)
Source: OSHA Madison case file
- Vermeer Saw Operator
95 dBA (7 hour sample)
Source: OSHA Aurora case file
- Jackhammering - 102 dBA (7.5 hour sample)
Source: OSHA Aurora case file
- Bobcat Operator Breaking Pavement 112 dBA (7 hour sample)
Source: OSHA Aurora case file
- Lateral Drilling - 97 dBA (6.5 hour sample)
Source: OSHA Aurora case file
- Lateral Drilling - 104 dBA (7 hour sample)
Source: OSHA Chicago North case file
- Partner Saw - 98 dBA (7 hour sample)
Source: OSHA Aurora case file
- 36" Wall Saw - 100 dBA (4.5 hour sample)
Source: OSHA Aurora case file
- Tuckpoint Grinding - 99 dBA (2.5 hour sample)
Source: OSHA Chicago North case file
- Sandblasting - 125 dBA (4 hour sample) Inside hood - 109 dBA
Source: OSHA Aurora case file
High Noise Exposures
Rules of Thumb
- Above 90 dBA when you have to raise your voice to be heard
standing next to a person
- Need protection:
- When using electric, gasoline, or air powered tools
- When sitting in an open cab of dozers, rollers, some cranes,
earth moving or road building equipment
Brief Overview - How Ears Work
- A-weighted response simulates the sensitivity of the human
ear at moderated levels.
How Does Excessive
Noise Damage Your Ears?
- Microscopic hair cells of the cochlea are exposed to intense
noise over time
- Hair cells become fatigued and less responsive, losing their
ability to recover.
- Damage becomes permanent resulting in noise-induced permanent
threshold shift.
Risk of Hearing
Loss
- Estimated Risk of Incurring Material Hearing Impairment as
a Function of Average Daily Noise Exposure Over a 40-year Working
Lifetime (source: NIOSH)
- Average Exposure 90 dBA 29%
- Average Exposure 85 dBA 15%
- Average Exposure 80 dBA 3%
What Is The
Purpose of Having a Hearing Test on a Regular Basis?
- An audiometric testing program is used to track your ability
to hear over time.
- Test records provide the only data that can be used to determine
whether the program is preventing noise-induced permanent threshold
shifts. It is an integral part of the hearing conservation program.
Case Study 1.
Teenage Girl
From the American Academy of Family Physicians website, Rabinowitz
article
FIGURE 1. Audiogram findings in the patient in case 1.
The area below the curves represents sound levels that the patient
could still hear.
(X = left ear; O = right ear)
Case Study 1
Conclusion
- "Temporary threshold shift" example
- Common in persons exposed to high noise
- Represents transient hair cell dysfunction
- Complete recovery can occur
- Repeated episodes of such shifts causes permanent threshold
shifts because hair cells in the cochlea are progressively lost.
Case Study 2 Factory
Worker Age 55
From the American Academy of Family Physicians website, Rabinowitz
article
FIGURE 2. Audiogram findings in the patient in case 2.
The area below the curves represents sound levels that the patient
could still hear.
(X = left ear; O = right ear)
Case Study 2
Conclusion
- Noise Induced Hearing Loss
- Speech discrimination and social function interference
- Difficulty in perceiving and differentiating consonant
sounds
- Words "run together"
- Sounds such as a baby crying or a distant telephone ringing,
may not be heard at all.
- Tinnitus
- Common symptom of noise overexposure
- Further interferes with hearing acuity, sleep and concentration.
- These impairments have been associated with social isolation,
depression and an increased risk of accidents.
Carpenter Hearing
Losses by Age
Source: NIOSH
Audiometric Test
Services
- Mobile Testing Services
- Fixed Site (Occ Health Clinics, Hospitals)
- Make sure they have a booth or partitioned area, not a
noisy room!
- How To Find
- Sound level meters
- A device that measures the intensity at a given moment
- Spot check
- Noise dosimeters
- A dosimeter is like a sound level meter except that it
stores sound level measurements and integrates the measurements
over time, providing an average noise exposure reading for
a given period of time, such as an 8-hour workday.
- Ear Plugs
- Ear Muffs
- Dual protection
- Active noise cancellation
- Amplification devices
- NRR calculations
What Hearing Protective
Devices Will Work Best?
Type |
Advantages
|
Disadvantages
|
Formable
Ear
Plugs (foam) |
- Cooler,
more comfortable under hot conditions
- Can
readily dispose of after each use
- Lightweight
|
- Irritation
to outer ear (for some people)
- Sometimes
fit problems
|
Reusable
Ear
Plugs (plastic) |
- Cooler,
more comfortable under hot conditions
- Can
be reused if cleaned properly
- Lightweight
|
- Irritation
to outer ear (for some people)
- Sometimes
fit problems
|
Ear
Muffs |
- Easy
to use no fit problems
|
- Not
as effective if anything (even glasses) breaks the seal
- Heavier/Warmer
than plugs
|
Noise Reduction
Rating
- A hearing protector's ability to reduce noise is its Noise
Reduction Rating (NRR).
- The greater the NRR, the better the noise attenuation.
- The NRR is usually listed on the hearing protector box.
Noise Reduction
Rating Calculation
- For A-weighted readings don't simply subtract NRR from exposure
level 1910.95 Appendix B
- (dBA - (NRR-7 dB))
- Example (plugs or muffs):
TWA = 109 dBA, NRR= 29
109 - (29-7) = 109 dBA - 22dB= 87 dBA
- Suggest you shoot for 80 dBA as a protection factor for poor
fit/use
NIOSH NRR Calculationhttp://www.cdc.gov/niosh/docs/98-126/
- Earmuffs - Subtract 25% from the mfr's NRR
- Formable earplugs - Subtract 50% from the mfr's NRR
- All other earplugs - Subtract 70% from the mfr's NRR
- Formula
Noise level = dBA - (derated NRR - 7)
Dual Protection
- Using plugs and muffs simultaneously
- Actual attenuation depends on many factors
- Reduction is not near what you would expect
- NRR calculation:
- Take the higher NRR and add 5 to the field adjusted NRR
Active Protection
- May help but not recognized by OSHA in NRR calculations
- Active headphones use destructive interference to cancel low-frequency
noise while still allowing the wearer to hear mid- and high-frequency
sounds such as conversation and warning sirens.
- Used extensively by pilots, active headphones are considered
indispensable in helicopters and noisy propeller-driven aircraft.
Hearing Protection:
Problems
- Undue reliance on protection without steps to reduce noise
exposure at source
- Poor choice of protector
- Incorrect fitting
- Inadequate maintenance
- Inconsistent use negates most of the protective effect
Noise Controls
for Construction Equipment
(Schneider et al., 1995)
Equipment
|
Noise
Controls |
Pile Driver
|
Enclosure,
muffler |
Stone
saw cutting |
Noise
control pad with water |
Handheld
impact drills |
Reduction
of reflected sound |
Circular
saw blades |
15Âș tooth
angle, new tooth configuration, slotted saw blades, viscoelastic
damping |
Pneumatic
tools |
Muffler
|
Pavement
breaker/ Rock drill |
Muffler,
enclosure of cylinder case and front head, moil damping |
Portable
air compressor |
Muffler,
acoustic enclosures |
Bulldozer
|
Bulldozer
Cab-liner material, enclosure, sound absorption in canopy, sealing
of all openings |
Wheeled
loader |
Absorption
of sound cooling air route |
Vibratory
roller |
Flexible
mounting for pump compartment |
Joint
Cutter |
Anti-vibration
mounting fixtures |
Noise Control
- Replace worn, loose, or unbalanced machine parts that cause
vibration.
- Keep machine parts well lubricated to reduce friction.
- Acoustical enclosures and barriers around generators
- Sound absorbing material and vibration isolation systems on
hand tools
- Quiet work practices - use rubber mallets to erect and dismantle
formwork.
Current Expectations
- 1926.52(d)(1) Implement hearing conservation programs for employees
exposed to 90 dBA average and above
- Audiograms
- Season long employees
- Long term year after year employees
- One year mobile testing van exception per 1910.95(g)(5)(ii)
- Don't forget exposed shop employees
- Training
- 1926.101 Hearing Protection
Proposed Standard
- Apply general industry standard to construction, 85 dBA average
and above
- Monitoring
- Audiograms
- Hearing Protection
- Training
- Recordkeeping
- Modifications proposed by the public under the rulemaking process
Worker's Compensation
Claim Statistics in Wisconsin - 2000
Loss of Hearing
- 725 claims
- Lost wage compensation $4, 855, 750
Hernia
- 1,267 claims
- Lost wage compensation $2,292, 408
Worker's Compensation
Claim Statistics in Wisconsin - 2001
Loss of Hearing
- 696 claims
- Lost wage compensation $5,727,122
Hernia
- 1,179 claims
- Lost wage compensation $2,270,330
Hearing Loss Affects
Safety Program
- Workers with NIHL may not hear audible warnings and safety
signals.
- Hearing impairment jeopardizes not only affected employees
but others who work with them.
- NIHL may interfere with daily life, especially during social
activities in noisy settings.
- High incidence of fatalities from being struck by objects,
transportation incidents, and frequency of fatal accidents from
moving machinesâespecially pedestrians.
- Break down in communication
- Increased effort to listen may lead to fatigue, anxiety, and
stress.
- Those affected may feel increasingly isolated from family and
friends.
- Some people with NIHL also suffer from tinnitus, causing
them to hear ringing, buzzing, rushing, whistling, or hissing
when there are in fact no sounds to be heard.
Contractor Comments
Hearing Conservation Programs
- "Audiogram cost was minimal"
- "Cost is the easy part."
- "Was not hard to do except the time to do dosimetry"
- "Insurance companies will often do monitoring"
- "Program was easily accomplished using a safety consultant"
- "Transient workforce is an issue"
- "Not a big problem to get employees to use hearing protectors.
Machine operators are good about it, others maybe not so good."
- "Have got to sell the program and get buy-in"
- Some of the unions could step up to the plate and offer audiograms
as a service to contractors."
- "It would be good to have an audiogram card for workers to
carry from job to job. Having a guy get 4-5 audiograms a year
will make him mad and discredit the program."
What You Can Do
Now
- Monitoring
- Equipment noise labels
- Purchase equipment with noise in mind
- Sell employees on hearing protector use
- Audiometric testing program
Contact Information
Kim Nipko
608-441-5388
kim.nipko@osha.gov
Charlie Shields
630-896-8700
charlie.shields@osha.gov
http://www.osha.gov/SLTC/constructionnoise/index.html
Extensive use of NIOSH, CPWR – Center for Construction Research and Training, and
the Construction Safety Association of Ontario materials was made.
We thank those organizations for the use of their information in
the advancement of hearing conservation.
|
This paper appears in the eLCOSH website with the permission of the author
and/or copyright holder and may not be reproduced without their consent.
eLCOSH is an information clearinghouse. eLCOSH and its sponsors are not
responsible for the accuracy of information provided on this web site, nor
for its use or misuse.
eLCOSH
| CDC | NIOSH
| Site Map | Search
| Links | Help
| Contact Us | Privacy Policy
|