Occupational Vibration and Noise Exposures in Forestry Workers

1
Occupational Vibration and Noise Exposures in
Forestry Workers

• Richard Neitzel, MS, IHIT
• Michael Yost, PhD
• University of Washington
• Department of Environmental Health

2
Background

• Forestry - important industry in Pacific NW
• 42.6 million acres of land in WA 16.8 million
  timber
• 28 owned by timber industry 19 by small tree
  farms
• 3.2 bbf private WA 1997 timber harvest 2.8 bbf
  in OR 98
• 1998 1,008 logging employers, 7,728 employees in
  WA
• Forestry work involves numerous hazardous
  occupational exposures
• US safety issues have received attention, but
  health issues increasingly important

3
Background

• Forestry worker occupational exposures
• Whole-body vibration
• Yarders, stackers, processors, shovels, trucks,
  mechanized cutters, bulldozers, graders
• Hand-arm vibration
• Above (through control mechanisms), plus chain
  saws, bucking saws, limbing saws, cutoff saws,
  axes
• Noise exposure
• Powered saws, heavy equipment, communications
  devices

4
Background

• Health consequences of occupational exposures
• Hand-arm (H-A) vibration
• Raynauds Phenomenon, Vibration White Finger,
  Carpal Tunnel
• Research done on forestry workers in Japan,
  Canada, Finland, etc.
• Raynauds in 9-27 CTS in 20 VWF in 9-51 in
  these countries
• Evidence of negative health effects, but few
  exposure data
• Whole-Body (W-B) vibration
• Degenerative spinal injuries, CNS and circulatory
  problems
• Noise Exposure
• Permanent, irreversible Noise Induced Hearing
  Loss (NIHL)

5
Background

• Existing W-B and H-A vibration-related research
• Teschke et al (90) noise monitoring as
  substitute for vibration monitoring in BC fellers
  using chainsaws vibration/noise correlation?
• Association between HAVS and NIHL (Iki et al, 85,
  86)
• H-A saw vibration levels documented, but no other
  equip, no W-B
• Existing noise exposure/NIHL research
• Forestry/logging 988 (6) of 16633 accepted WA
  claims 1984-96
• IR 33.2 accepted claims/10-3 FTE-yrs (state fund
  employers only) for 3,922 workers all industries
  (state fund only) 1.26
• Mean settlement amount, WA compensated claims
  5,980
• Number of claims increasing supralinearly each
  year (Daniell 99, 00)

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Research Goals

• To quantify noise and vibration exposure levels
• Collect data in such a way as to allow for
• Characterization of typical forestry noise and
  vibration exposures by task, tool, trade,
  operation
• Measurement of correlation of noise and vibration
  levels
• Modeling of exposure variables to predict likely
  exposures
• Recommendations to participating employers on
  appropriate control strategies, with ability to
  identify problematic equipment
• Assessment of potential of worker self-reporting

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Exposure Standards - Noise

• WISHA PEL 296-54-51130 (ref. General Industry)
• NIOSH REL DHHS (NIOSH) publication 98-126

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Exposure Standards - Vibration

• WISHA
• Reasonable precautions shall be taken to protect
  workers against hazardous effects of unavoidable
  vibration exposure (WAC 296-62-09009)
• Others

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Exposure Standards - Vibration

• H-A and W-B vibration measured in 3 axes

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Exposure Standards - Vibration

• ACGIH HAV TLV Exposure Values
• ACGIH WBV TLV Exposure Values

11
Methods

• Approached two companies for access
• Company A (Shelton timberlands base)
• 286 thousand acres owned in WA 2,000 WA emp
• Company B (Longview timberlands base)
• 1.45 million acres in WA 8,829 WA emp
• UW exposure interest cutting and logging crews
• Company A 100 contract
• Company B 50 contract (gyppo), 50 in-house
• In-house cutting access problematic, contractors
  not part of study, so logging, road construction,
  log handling included

12
Methods

• Sites selected on ease of access or escort
  availability
• Workers participated voluntarily hats and shirts
  offered as participation incentives
• Data collected on 10 days over 8 weeks (Mar
  31-Jun 28, 99)
• Exposures assessed at various sites
• 1 felling, 4 yarding/landing, mult. road
  construction, 2 log handling
• Workers filled out self-report task data cards
  listing timing of daily tasks/tools
• Workers observed periodically to assess
  self-report accuracy

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Methods
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Methods

• Noise exposure assessment
• 10 Quest Q-300 datalogging dosimeters
• Sample multiple times/second, up to three data
  channels simultaneously
• Average readings over one minute, logs data
• Records one minute LOSHA, LEQ, Lmax, Lpeak
• PC download yields one minute data plus TWA, time
  over ceiling, high max, high peak, runtime
• Dosimeters worn on belt or vest full-shift,
  microphone attached to workers lapel/suspenders
  within 4 in. of ear

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Methods

• Vibration exposure assessment
• Bruel Kjær 2231 precision SLM with BK 2522
  Human Vibration Module
• Logs continuously throughout vibration event
• PC download yields event runtime, overall AEQ,
  and Lmax, Lmin, Lpeak, and AEQ for three channels
• Triaxial measurements using three BK 4374 mini
  piezoelectric accelerometers or one 4322 triaxial
  seat accelerometer

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Results

• 43 workers participated (2 of them twice)
• 19,325 minutes of noise monitoring
• 744 minutes of vibration measurement
• Researcher observation/worker report comparison
• 672 minutes of dual observation/reporting
• For tool use, Cohens kappa (statistic of
  agreement) 0.885
• For task performance, Cohens kappa 0.689

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Results - Noise Exposure

• 44 TWAs, 42 valid
• Overall NIOSH mean 90.2 5.1 dBA
• Overall OSHA mean 86.1 6.2 dBA
• Mean duration 7 hr 39 min (1 hr 24 min)
• 59 of OSHA TWAs exceeded 85 dBA, 29 exceeded 90
  dBA
• 83 of NIOSH TWAs exceeded 85 dBA, 48 exceeded
  90 dBA

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Results - Noise Exposure
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Results - Noise Exposure
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Results - Noise Exposure
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Results - Noise Exposure
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Results - Noise Exposure
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Results - Noise Exposure

• WISHA 1-minute sound levels
• Noisiest task
• Unbelling chokers at landing (mean 89.4 dBA)
• Noisiest tool
• Cable Yarder (mean 81.3 dBA)
• WISHA TWAs
• Noisiest trade
• Cutter (mean 95.0 dBA)
• Noisiest operation
• Tree felling (mean 95.0 dBA)

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Results - Vibration Exposure

• 178 measurements, 166 valid 67 H-A, 99 W-B
• Hand-Arm mean duration 2 min 11 sec (218)
• Whole-Body mean duration 5 min 56 sec (637)

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Results - Vibration Exposure
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Results - Vibration Exposure
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Results - Vibration Exposure
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Results - Vibration Exposure
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Results - Vibration Exposure
Results - Vibration Exposure
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Results - Vibration Exposure

• Whole Body Vibration
• Bulldozer, FEL, Grader AEQz gt4.84 m/s2
• 2.5-4 hrs/day recommended by TLV, but operated 8
  hrs
• Overall AEQz for Operating Vehicle 2.39 m/s2
  4-8 hrs/day
• Hand-Arm Vibration
• Notching Stumps AEQx 23.36 m/s2
• gt12 m/s2 less than 1 hr/day recommended by TLV
• Chainsaw, Felling Trees AEQx gt 8 m/s2
• 1-2 hrs/day recommended by TLV, but done for 4-5
  hrs

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Conclusions

• Large percentage of forestry workers measured
  were overexposed to noise by WISHA and NIOSH
  standards
• Task/tool based assessment allows prediction of
  vibration and noise exposures in unsampled
  forestry workers
• Average worker exposure durations available via
  data card
• Exposure results generally agree with literature
• Poor correlations found between noise and
  vibration levels
• Commission of European Communities (CEC)
• Summary AEQ 0.5 m/s2 action level (AL) for 8
  hrs WBV
• Every vehicle measured exceeded CEC AL

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Conclusions

• Vibration control technology available and
  feasible
• Reductions successful in forestry workers of
  other countries
• Finland and Japan VWF, 1960s-70s 34-66
  1980s-90s 5-17
• Finland 1972-90 chainsaw vibration dropped from
  14 to 2 m/s2, VWF from 40 to 5 (saws lighter,
  smaller gripping force)
• Antivibration gloves and saws and administrative
  controls (limit exposure duration, keep workers
  warm) effective
• 13.4 of 222 workers with AV chain saw experience
  had VWF 51.7 of those with non-AV saw
  experience had VWF
• Vibration-reducing seats on heavy equipment,
  maintenance

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Conclusions

• Noise control technology available and feasible
• Insulation heavy equipment cabs or engine
  compartments
• Active noise reduction headsets for equipment
  operators
• Air conditioning in cabs to allow window closure
• Double HPD use (plugs and muffs) in fellers
  (level of protection already used) adds up to 5
  dB to greater NRR
• Effective HCP implementation
• In place in these companies, but elsewhere?
• More research required on small contractor ops

34
Acknowledgements

• Funded by the UW Pacific Northwest Agricultural
  Safety and Health Center
• Thanks to Weyerhaeuser Co and Simpson Timber
• Mother Nature for her half-hearted cooperation