title: Hearing conservation in the primary aluminium industry.
abstract: BACKGROUND
  Noise-induced hearing loss has been an intractable problem for heavy industry.
  
  
  OBJECTIVE
  To report our experience in reducing the incidence of age-corrected confirmed 10 dB hearing shifts (averaged over 2, 3 and 4 kHz) in employees in the primary aluminium industry in Australia over the period 2006-13.
  
  
  METHODS
  We analysed annual audiometric data to determine the number of permanent hearing shifts that occurred in employees in two bauxite mines, three alumina refineries and two aluminium smelters. Annual hearing shift rates were calculated based on the number of employees tested per year. Hearing conservation initiatives undertaken during the study period are described. An assessment of similar exposure group noise exposures was also undertaken to determine the magnitude of noise exposure reduction during the study period.
  
  
  RESULTS
  Across all operations, hearing shift rates declined from 5.5% per year in 2006 to 1.3% per year in 2013 (P < 0.001). The decline in shift rates was greater in mines and refineries, where baseline shift rates were higher, than in smelter workers. Modest reductions in noise exposure occurred during the study period.
  
  
  CONCLUSIONS
  We observed a substantial decline in hearing shift rates during the study period. We describe the hearing conservation initiatives that were collectively associated with this decline. We suspect these initiatives could be deployed relatively easily and at modest cost in other industries with noise-exposed employees.
authors.affiliation: Alcoa of Australia, PO Box 252, Applecross, Perth, WA 6953, Australia, michael.donoghue@alcoa.com.au.
authors.forename: A M
authors.initials: AM
authors.lastname: Donoghue
authors.affiliation: Alcoa of Australia, PO Box 252, Applecross, Perth, WA 6953, Australia.
authors.forename: N
authors.initials: N
authors.lastname: Frisch
authors.affiliation: Alcoa Corporate Centre, 201 Isabella Street, Pittsburgh, PA 15212-5858, USA.
authors.forename: C
authors.initials: C
authors.lastname: Dixon-Ernst
authors.affiliation: Occupational Hygiene Solutions Pty Ltd, 26 Leake Street, Peppermint Grove, Perth, WA 6011, Australia.
authors.forename: B J
authors.initials: BJ
authors.lastname: Chesson
authors.affiliation: Division of General Medical Disciplines, Stanford University School of Medicine, 1265 Welch Road, MSOB X-338, Stanford, CA 94305-5411, USA.
authors.forename: M R
authors.initials: MR
authors.lastname: Cullen
mesh_terms: D000535:Aluminum; D001299:Audiometry; D001315:Australia; D004430:Ear Protective Devices / Q000706:statistics & numerical data; D004784:Environmental Monitoring / Q000379:methods; D006317:Hearing Loss, Noise-Induced / Q000209:etiology* / Q000503:physiopathology / Q000517:prevention & control; D006801:Humans; D015994:Incidence; D008669:Metallurgy; D009623:Noise, Occupational / Q000009:adverse effects* / Q000517:prevention & control; D009784:Occupational Diseases / Q000209:etiology* / Q000503:physiopathology / Q000517:prevention & control; D016273:Occupational Exposure / Q000009:adverse effects* / Q000517:prevention & control
chemical_list: D000535:Aluminum
keywords: Audiometry; hearing loss; minerals processing; mining; noise; noise-induced hearing loss; smelter.