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Noise and Hearing Loss in the Metal Manufacturing Industry David Welch Gareth John Alla Grynevych Peter Thorne.

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Presentation on theme: "Noise and Hearing Loss in the Metal Manufacturing Industry David Welch Gareth John Alla Grynevych Peter Thorne."— Presentation transcript:

1 Noise and Hearing Loss in the Metal Manufacturing Industry David Welch Gareth John Alla Grynevych Peter Thorne

2 Day 1: Tour of facility Employees interviewed individually - Explanation of project - Interview - Disposable earplug assessment (Veri-Pro) Sound level meter measurements Day 2: Hearing tests (otoscopy, tympanometry, and audiometry) Dosimetry Research Protocol

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5 Participants 27 Companies 160 Employees 155/160 Male 11/160 Clerical staff (including all 5 females)

6 Noise Levels

7 Noise Levels by Company Size (Production workers only) There was no difference in mean noise level (F(2,135)=1.257, p=0.288)

8 Noisy Equipment Top Ten RankEquipment nameMean Leq (dB(A)) 1Air gun96.9 2Angle grinder93.2 3Pedestal grinder90.1 4Saws88.7 5Roll former Steelworker - punch and sheer Linisher82.5 8Electric drill82.1 9Air compressor Guillotine81.6

9 Impulse Noise Top Ten RankSource of impulse noiseMean Lpeak (dB(C)) 1 Dropping sheet steel onto surface of an ArcWriter machine Sledge hammering a mild steel girder Dropping a steel bar onto a concrete floor from approx 0.5m Dropping a steel bar onto a concrete floor from approx 0.5m Sledge hammering a steel plate on a metal work surface Dropping sheet steel on top of other sheet steel from approximately 1m Hammering (ball-pein hammer) a galvanised steel sheet, on a metal work surface Rolling over a steel girder, on a metal stand Centre punching a steel girder Dropping a large, hollow, aluminium tube onto concrete floor from approximately 1m 124.7

10 The mean age was approximately 40 years. Age (years)

11 Lifetime Work Noise Exposure

12 Noise Exposure and Age

13 Hearing Thresholds by Age

14 Audiogram Notch Criteria: 1.Poorer threshold at 4 or 6 kHz than at 2 kHz AND 2.Better threshold at 6 or 8 kHz than at 4 kHz AND/OR 3.Better threshold at 8 kHz than at 6 kHz AND 4.Notch depth >20 dB HLAND 5.Bilateral notches

15 Audiogram Notch 15 people had bilateral notches according to the criteria – 0/40 (0%) years – 4/39 (10%) years – 6/54 (11%) years – 5/27 (19%) 51 years or more

16 Hearing Threshold by Age and Notch

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19 Hearing Disability vs Hearing Loss Ability to hear in noisy backgrounds was impaired in 25% of participants

20 Tinnitus Amount of tinnitusNumberPercent (UK males ages 18-80) Never Up to 5 minutes Rarely1811 Half the time111 Most of the time532 All the time854 Responses to the question: In the last 12 months, when you are awake and it is quiet, have you experienced tinnitus...?

21 Hearing Protection 160 workers interviewed 86 (54%) used earmuffs 75 (47%) used earplugs 13 (8%) used either 12 (8%) used neither (Of these 12, 5 were production workers with Leq scores : 89.7, 86.6, 84.2, 81.9, and 71.6 dB(A). )

22 Lifetime Noise Exposure without HPE (Overall, there was a correlation between age and years spent working in noise without HPE (r=0.480, p<0.001))

23 Poorly Fitted Earplugs

24 Older Workers Tended to Fit Earplugs Less Well

25 Poorly Fitted Earplugs = Poorer Hearing

26 Conclusions High noise levels in metal manufacturing Half of production workers exposed >85dB(A) NIHL was not widespread (15/160 with measureable notch) Hearing disability was present in a quarter of workers – but not well linked with hearing loss HPE used by almost all production workers HPE used always by younger workers (up to approximately 40 years) Suggestive of greater awareness of the impact of noise in younger workers Poor fitting of foam earplugs was common Poor fitting of foam earplugs was associated with NIHL

27 Acknowledgements Thanks to the many companies and individuals who gave their time to participate in this research. Thanks to Dr John Wallaart, ACC Programme Manager, for his friendly advice and assistance. Thanks to John Skudder, ACC Workplace Safety Programme Manager, for his invaluable help in getting the research started and for sharing his knowledge along the way. Thanks to Zaneta Schumann, Department of Labour Service Manager, and the Auckland North Office of the Department of Labour for their kind help and interest in the research. Thanks to Sperian for the generous loan of the VeriPro system.


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