Repository logo

Browsing by Author "Autenrieth, Daniel, committee member"

Now showing 1 - 5 of 5
  • Thumbnail Image
    ItemOpen Access
    Employee noise exposure and octave band analysis in a manufacturing setting
    (Colorado State University. Libraries, 2023) Gieseck, Darren, author; Brazile, William, advisor; Autenrieth, Daniel, committee member; Gutilla, Margaret, committee member
    Worker exposure to hazardous levels of noise continues to be a concern in United States (US) industries. The National Institute for Occupational Safety and Health has estimated that twenty-two million US workers are exposed to hazardous levels of noise each year, increasing the risk for noise-induced hearing loss (NIHL). One industry sector of concern for worker exposure to noise is metal can manufacturing because of the types and number of machines used in the production areas. To help further characterize the risk NIHL in the metal can manufacturing sector, a comprehensive noise evaluation was performed at a manufacturing site that produced aluminum metal cans. The purpose of this study was to (1) determine if workers in a metal can manufacturing facility were overexposed to hazardous levels of noise that could potentially result in NIHL; (2) determine the machinery frequencies greater than 85 dBC to which employees were exposed; and (3) provide sound mitigation recommendations to the facility's safety team. Area noise levels were collected with a sound level meter (SLM) and personal noise samples were taken using wearable noise dosimeters. 30 production employees participated in sampling over the course of five days and their measured work shift noise exposures were compared to published occupational exposure limits to determine if they were at increased risk of hearing loss. Personal noise exposures were compared to the Occupational Safety and Health Administration's (OSHA) noise Action Level (AL) and Permissible Exposure Limit (PEL); the American Conference of Governmental Industrial Hygienists' (ACGIH) Threshold Limit Value (TLV); and the National Institute for Occupational Safety and Health's (NIOSH) Recommended Exposure Level (REL). Of the 30 employees sampled, 100% exceeded the OSHA AL, 100% exceeded the OSHA PEL, and 100% exceeded the NIOSH REL/ACGIH TLV. To provide statistical support of these findings, a 95% confidence interval was calculated for each occupational exposure standard along with upper and lower prediction limits. Additionally, the frequencies greater than 85 dBC obtained from the area noise samples associated with the production machinery ranged from 63 Hz – 6,300 Hz with noise levels that ranged from 97.1 dBC – 99.6 dBC and Z-weighted frequencies greater than 85 dB ranged from 32 Hz – 8,000 Hz. From these findings, noise mitigation recommendations were provided that were focused on establishing hearing attenuation to 80 dBA. This involved ongoing fit testing of hearing protection for employees, training, and addressing the specific frequencies associated with each machine type.
  • Thumbnail Image
    ItemOpen Access
    "Exposure to respirable crystalline silica during five OSHA Table 1 tasks and the effectiveness of dust controls, the contribution of background silica dust to personal exposures, and the use of a photometric instrument to assess silica dust exposure in real time"
    (Colorado State University. Libraries, 2021) Cothern, Emily J., author; Brazile, William, advisor; Reynolds, Stephen, committee member; Autenrieth, Daniel, committee member; Fisher, Gwen, committee member
    To view the abstract, please see the full text of the document.
  • Thumbnail Image
    ItemOpen Access
    Noise characterization of oil and gas operations
    (Colorado State University. Libraries, 2016) Radtke, Cameron, author; Brazile, William, advisor; Autenrieth, Daniel, committee member; Lipsey, Tiffany, committee member
    In cooperation with The Colorado Oil and Gas Conservation Commission (COGCC), researchers at Colorado State University (CSU) conducted area noise monitoring at 23 oil and gas sites throughout Northern Colorado. The goals of this study were to: (1) measure and compare the sound levels for the different phases of oil and gas development sites; (2) evaluate the effectiveness of sound barriers; and (3) determine if sound levels exceeded the COGCC noise limits. The four phases of oil and gas development include drilling, hydraulic fracturing, completion and production. Sound measurements were collected using the A- and C-weighted scales. Octave band analysis was also performed to characterize the frequency spectra of the sound measurements. Noise measurements were collected using noise dosimeters and a hand-held sound-level meter at specified distances from the development sites in each cardinal direction. Data were analyzed using descriptive statistics and a t-test was used to determine significant differences in noise levels for drilling sites with and without sound barriers. In addition, noise maps were developed to illustrate the behavior of the noise propagation. At 117 yards, the sound-measurement distance specified by the COGCC noise rule, drilling, hydraulic fracturing, and completion sites without sound barriers exceeded the maximum permissible noise levels for residential and commercial zones (55 dBA and 60 dBA, respectively). In addition, drilling and hydraulic fracturing sites with sound barriers exceeded the maximum permissible noise level for residential zones. Production sites were within the COGCC permissible noise level criteria for all zones. At 117 yards from the noise source, all drilling, hydraulic fracturing and completion sites exceeded 65 dBC. Current sound wall mitigation strategies reduced sound levels in both the A- and C-weighted scales. However, this reduction in noise was not sufficient enough to categorize drilling and hydraulic fracturing sites as compliant with the current COGCC noise regulations.
  • Thumbnail Image
    ItemOpen Access
    Noise exposure in steel stud construction: noise characterizations and tool limit guidance for commercial framers
    (Colorado State University. Libraries, 2023) Schutt, David, author; Brazile, William, advisor; Autenrieth, Daniel, committee member; Lipsey, Tiffany, committee member; Van Dyke, Mike, committee member
    Noise exposure in construction is well-demonstrated to be hazardous to hearing, with high rates among construction workers of occupational noise-induced hearing loss. This study focused on an under-studied population of construction workers: Commercial framers who cut and install steel studs as their primary task. This study used personal noise dosimetry and task assessments to characterize the noise exposures of this population, and to develop implementable recommendations to decrease hazardous occupational noise exposure for this population of workers. Sound pressure levels of common power saws at the framers' hearing zone was hazardous, with Leq log-transformed means of 107.2 dBA and Lpeak means of 120.1 dBC during saw use. Noise dose among this population ranged from 5.8 – 61.4% of the Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) and from 63.9 – 823.2% for the National Institute for Occupational Safety and Health (NIOSH) recommended exposure limit (REL). Mean ambient noise dose equivalent at the study sites was 1.4% for OSHA PEL criteria and 12.4% for NIOSH REL criteria. Overall, installers had significantly lower REL doses than cut persons (p = 0.016). Octave band analysis showed a slight upward trend of higher sound pressure levels at higher frequencies. Recommendations for task limitations were developed for isolated use of power saws, the powder-actuated tool (PAT) nailer, and the impact driver. Generalized cuts of steel studs without hearing protectors were limited to 13 – 14 cuts per worker per day for any saw and any stud type. Shots with the PAT nailer were limited to <2 shots per day per worker without hearing protectors, 10 – 13 shots per day with foam earplugs, 27 – 34 shots per day with earmuffs, and 86 – 108 shots per day with double hearing protection (earplugs plus earmuffs).
  • Thumbnail Image
    ItemOpen Access
    Occupational noise exposure and hearing assessment of hydraulic fracturing workers: quiet versus conventional fleets
    (Colorado State University. Libraries, 2024) Blevens, Melissa S., author; Brazile, William, advisor; Tsai, Candace Su-Jung, committee member; Van Dyke, Michael, committee member; Autenrieth, Daniel, committee member; Lipsey, Tiffany, committee member
    Oil and gas extraction companies are exempt from implementing hearing conservation programs for their workers according to the Occupational Safety and Health Administration's (OSHA) noise standard. The occupational noise exposure and hearing status of these workers has not been published in scientific literature before the present study, presumably due to this exemption. In this study, area and personal noise exposures and worker hearing acuity were measured at both conventional and quiet hydraulic fracturing fleets, allowing a comparison between the fleets. Quiet fleets refer to the use of engineering controls to decrease noise levels of the pumps while conventional fleets do not employ these measures. In both fleets, the authors conducted personal noise dosimetry, equipment noise measurements, and pure tone audiometry pre- and post-work shift to determine if there were temporary threshold shifts (TTS) in hearing. Based on the personal noise dosimetry results, 42/50 (84%) of the quiet fleet and 34/34 (100%) of the conventional fleet workers sampled were at or over 100% noise dose according to the American Conference of Governmental Industrial Hygienists' (ACGIH) noise Threshold Limit Value (TLV). Based on the OSHA Permissible Exposure Limit (PEL) noise criteria, 9/50 (18%) of the quiet fleet workers and 15/34 (44.1%) of the conventional fleet workers were at or over 100% noise dose. Workers in both fleets experienced TTS, but no significant difference was observed between the types of fleets in relation to TTS. Most equipment of both fleets exceeded 85 decibels, but the pumps of the quiet fleet were ~14 dB lower than those of the conventional fleet. Although the quiet fleet noise controls reduced personal noise exposure, a portion of the quiet fleet workers sampled still faced noise levels that could increase the risk of hearing loss. The researchers suggest the initiation of a hearing conservation program despite OSHA exemption to safeguard worker health and recommend workers involved in certain job tasks employ dual hearing protection based on the exposure monitoring results.