Introduction Noise and Occupational Hearing Loss

Transcription

1 Introduction Noise and Occupational Hearing Loss Dr Steven Sadhra Senior Lecturer & Director of Education for Occupational Medicine PhD, MIOSH, MFOM, FFOM (Hon.) Institute of Occupational and Environmental Medicine School of Population and Health Sciences University of Birmingham

2 Legislation The Control of Noise at Work Regulations 2005 (Noise at Work Regulations 1989)

3 HSE Statistics New NIHL cases qualified under IIDB scheme -215 (2007/08), 175 (2006/07) 2008/09 an estimated 17,000 individuals who worked in the last 12 months were suffering hearing problems believed to be work related - Labour Force Survey

4 Risk Assessment (RA) Steps 1. Noise sources & properties 2. Who might be exposed when & how 3. Evaluate risk taking account of controls 4. Record findings 5. Review the RA

5 Exposure Limit Value : Daily / Personal Peak Sound Pressure 87 db (A) 140 db (C) Lower -Exposure Action Value (EAV): Daily Personal Peak Sound Pressure 80 db (A) 135dB (C) Upper -EAV: Daily Personal Peak Sound Pressure 85 db (A) 137 db (C)

6 Noise Measurement Units db (A) L EP,d Decibel Logarithmic scale 3dB doubling A Weighting db (A) Daily personal exposure level L Cpeak Peak sound pressure level

7 Risk Assessment (Reg.5) An employer who carries out work which is liable to expose any employees to noise at or above 80 db (A) shall make a suitable and sufficient assessment of the risk

8 Health Surveillance (R9)- When? If the RA indicates that there is a risk to the health.without taking account of noise reduction provided by hearing protection L EP,d regularly above 85dB(A) Occasionally >85dB(A) OR between 80 & 85 db (A), provide HS for individuals who may particularly sensitive to noise.

9 Hearing loss Conductive External & middle ear Interference with sound transmission, usually reversible Sensorineural Inner ear or auditory nerve damaged Irreversible Characteristic audiogram pattern Mixed

10 NIHL-Work Risk Factors Noise level (amplitude) Frequency Duration of exposure Exposure pattern Continuous, Intermittent, Varying or Impulse Use of ear protection

11 Sensorineural HL Other Causes Vascular Ototoxicity Head trauma Infections Acoustic Neuroma Hereditary Presbycusis Meniere s disorder

12 Prescribed disease A10 At least 50 db in each ear, being the average of HL at 1, 2 & 3 KHz Any occupations involving: example Grinding tools, textile manufacture, woodworking machines, Pneumatic percussive tools etc.

13 Hearing Conservation Programmes Purchase policy (machines/tools) Noise surveys Diagnosis Criteria Workplace Risk assessments Rehabilitation Compensation Selection of noise control measures Legal requirements Audiometry Records Education & training Audit & inspections

14 NIHL- Diagnosis History (medical & occupational) Exposure duration & pattern Symptoms Otoscopic examination Tuning fork test results (Rinne & Webber) Audiogram Noisy hobbies

15 Why do Audiometry? Early Identification & measurement of HL Establish baseline for individuals Noise Education Identify the more vulnerable individuals Assess effectiveness of noise controls

16 Audiometry -QC Equipment calibration (EN 26189:1991) Annual lab. tests Calibrate ear phone with audiometer Test environment (EN 26189) Sound proof booth Noise excluding headsets

17 TTS Eliminate influence Test before high noise exposure Before start of work Additional HP before test in noisy areas At least 16hrs from high noise levels before testing to exclude any contribution (CNAW 2005)

18 Frequency of testing Baseline before employment Annual tests for the first 2 yrs, then three yearly More frequent, if change in either exposure conditions or hearing levels

19 Evaluating Audiograms o Cat. 1 -Acceptable hearing ability o Cat. 2 -Mild hearing impairment o Cat. 3 -Poor hearing o Cat. 4 -Rapid hearing loss o Unilateral

20 Classification of audiograms in to warning (W) and referral ( R) levels MALE FEMALES W R W R (The Control of Noise at Work Regs. 2005) 41

21 Evaluation-Σ1,2,3,4 &6 KHz Cat. 1 (Acceptable hearing ability) If the sum for either ear is below the Warning level Cat. 2 (Mild hearing impairment) -W If the sum for either ear the warning level Cat. 3 (Poor hearing) -R If the sum referral level for either ear Cat. 4 (Rapid hearing loss) (Σ 3,4,and 6KHz)-R Previous test within last 3 yrs, 30dB Unilateral Σ1,2,3,4 -R Difference between ears 40dB

22 Action /Advice Assess rate of progression (Cat.1 & Cat.2) Formal notification to employee presence of hearing loss (Cat. 2) Reconsider frequency of testing (Cat.4) Arrangement for referral (Cat.3, Cat.4, Unilateral HL, symptoms) Review noise exposure assessment (Cat.2,C3,C4) Record action taken and advice given

23 Noise & Health Questionnaires Part 1 Part 2 Baseline At Each Subsequent Test Questionnaires included in The Control of Noise at Work Regulations 2005 (See Appendix 6)

24 Noise Control Hierarchy Source-Path-Receiver Can the risk be eliminated /reduced by doing the work in a different way Can the work, process or machine be modified to reduce emissions Possible to replace tools and equipment with lower noise alternatives Can the workplace and workflow be arranged to separate people from noise Can the noise reaching people be reduced by controlling it on its path from the sources The Control of Noise at Work Regs 2005

25 Noise Control methods Organisational controls (job design, job rotation) Workplace design (layout of workplace) Buying low noise machinery Machine design (avoiding impacts, air turbulence) Providing enclosures, screens, barriers Damping (adding material to reduce vibration) Isolation (separating machine from supporting structures) Fitting silencers Refuges (enclosure of people) Maintenance of machinery

26 Hearing Protection (Reg.7) (1) If an employer is unable by other means to reduce the level of noise to below the 85dB(A), he shall provide personal HP (2) An employer who carries out work which is likely to expose an employees to noise at 80dB(A) or above he shall make available HP on request.

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