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Browsing Theses and Dissertations by Author "Adams, Karin, committee member"

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    Noise exposure and evaluation at tire changing facilities
    (Colorado State University. Libraries, 2019) Willson-Kerns, Cory, author; Brazile, William, advisor; Adams, Karin, committee member; Fisher, Gwenith, committee member
    The purpose of this study was to (1) determine if workers in the tire changing industry are overexposed to hazardous noise that could result in occupational hearing loss; and (2) determine the maximum number of tire changes that could be performed without exceeding occupational exposure limits. Personal noise dosimetry data were compared to published occupational noise exposure limits to assess compliance. The noise dosimetry results were then extrapolated against the number of tire changes to determine if there was a relationship between the number of tire changes and employee noise exposures. Thirty (30) full-shift noise-exposure samples were collected on tire technicians using Larson-Davis 703 audio dosimeters in three tire-changing facilities. The technicians recorded the number of tires changed during their shift. The eight-hour time weighted averages were recorded for each subject following the Occupational Safety and Health Adminsitration (OSHA) permissible exposure limit (PEL) and action level (AL); and the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV). Each sample was evaluated against the number of tire changes performed in the shift. In addition, area noise samples of specific pieces of tire-changing equipment and processes were taken with a sound level meter. It was determined from the 30-sample data set that only one of the 30 technicians was exposed at or above the OSHA noise action level of 85dBA (as an 8-hour TWA). Eighteen (18) of the 30 employees were exposed above the ACGIH noise TLV and no employees exceeded the OSHA noise PEL. Based on the area noise samples, noise in the tire changing facilities appeared to be largely intermittent with peak noise levels exceeding 140dB. The findings of this study are that tire technicians were not exposed above the OSHA PEL at least up to 40 tire changes per shift but may still be exposed to hazardous levels of noise. A 95% confidence interval for each of the three categories of noise analyses (i.e., PEL, AL, TLV) was calculated to determine the average noise exposure for each number of tire changes. In addition, a 95% prediction interval was calculated to determine the noise exposure level for an individual worker chosen randomly for a specific number of tire changes. Last, it was determined from the area noise sampling that the air ratchet, Cheetah, and tire-changing machine contributed the most to the overall noise exposure.