128
PROSPECTIVE NOISE-INDUCED CHANGES TO HEARING AMONG CONSTRUCTION INDUSTRY
APPRENTICES.
N. Seixas, B. Goldman, L. Sheppard, R. Neitzel, S. Norton, University of Washington, Seattle, WA; S. Kujawa, Massachussetts Eye and Ear Infirmary, Boston, MA.
Early development of noise-induced hearing loss among noise-exposed workers has been poorly characterized by existing methods. In order to characterize the development of noise-induced damage to hearing, we prospectively monitored hearing and noise exposure among a cohort of newly enrolled construction industry apprentices and a comparison group of graduate students, using standard pure-tone audiometry and distortion product otoacoustic emissions (DPOAEs). Three-hundred-twenty-eight subjects (632 ears) were monitored annually an average of 3.4 (± 0.8) times. In parallel to these measures, noise exposure and hearing protection device use were extensively monitored during construction work tasks. Trade-specific mean exposure LEQ levels, with and without accounting for the variable use of hearing protection in each trade, were calculated and used to group subjects by trade-specific exposure level. Mixed effects models were used to estimate the change in hearing outcomes over time for each exposure group, while adjusting for age, gender, previous noise exposure, and baseline audiometry, and accounting for subject and ear. Small but significant exposure-related changes in DPOAEs, on the order of -0.5 dB per year at 90 dB exposure, were observed, especially at 4 kHz, with less clear but similar patterns observed at 3 kHz. Pure tone audiometric thresholds displayed only slight trends toward increased threshold levels with increasing exposure groups. The effect of using alternative approaches to noise exposure metrics are explored. The results indicate that construction apprentices in their first three years of work, with average noise exposures under 90 dBA, have measurable losses of hearing function. Despite numerous challenges in using DPOAEs for hearing surveillance in an industrial setting, they appear somewhat more sensitive to these early changes than are evident with standard pure tone audiometry.
129
EFFECTIVENESS OF HEARING PROTECTION IN THE CONSTRUCTION INDUSTRY.
R. Neitzel, N. Seixas, University of Washington, Seattle, WA.
Hearing conservation programs in the construction industry are rare, and, where present, often rely on workers’ use of hearing protection devices (HPDs) to reduce exposures below 85 dBA. This reliance on HPDs for protection from high noise is problematic, as the degree of protection provided by an HPD depends on not only the HPD’s attenuation level, but also the amount of exposure time during which the HPD is used. Noise exposure and HPD use data drawn from construction apprentices employed in nine construction trades were analyzed to assess HPD effectiveness. A combination of one-minute dosimetry noise levels and simultaneous self-reported HPD use was evaluated, as were occupational HPD use data collected by questionnaire as part of a longitudinal study of noise exposure and hearing loss in construction workers. Direct measurements of earplug attenuation were also made on workers using the FitCheck attenuation measurement system. The mean full-shift noise levels across more than 700 workshifts exceeded 85 dBA for all but one trade, and nearly one-third of all monitored minutes were above 85 dBA. Workers used HPDs less than one-quarter of the time they were needed (i.e., when exposure levels exceeded 85 dBA.) Workers who reported “always” using HPDs in high noise on questionnaires actually wore them only one-third of the time they were needed. Direct attenuation measurements showed that, on average, workers achieved more than 50% of the labeled Noise Reduction Rating of the their earplug, but that the variability in achieved attenuation was large. Lastly, when the measured earplug attenuation levels and use time data were combined, the effective protection afforded by HPDs was less than 3 dB on average. Overall, HPD use reduced overexposure situations for only 20% of the measured full-shift exposures. These results demonstrate the need for better hearing conservation efforts in the construction industry.
130
ACTIVE CONTROL OF LONGWALL COAL MINING NOISE.
J. Slagley, U.S. Air Force, Morgantown, WV; A. Rai, S. Guffey, Y. Luo, West Virginia University, Morgantown, WV.
A NIOSH study indicated that 90% of coal miners experience hearing loss by the age of 50, compared to a 10% rate of loss by age 51 for the non-exposed comparison population. Due to the high degree of mechanization and confined environments, noise levels at longwall mining faces routinely exceed 90 dBA. The two major sources of noise in a longwall face are: machine noise produced by the mining machines, and background noise produced by the breakage and movement of surrounding rock strata.
Eleven underground surveys were conducted on longwall coal mining faces. Noise sources which most contributed to the miners’ dose were identified for interventions, with particular attention to those that could be reduced using active noise control techniques. The one selected for further analysis was the headgate operator, who is exposed by the stageloader/ crusher, a machine which crushes the coal coming from the face and loads it onto a belt for removal from the mine.
Active noise control (ANC) experiments were conducted on a laboratory model of the stageloader/crusher using recorded underground stageloader noise. ANC achieved a reduction of 7–10 dB (5–7 dBA) overall, mostly at frequencies below 1000 Hz. For the next tests, the recorded stageloader noise was broadcast inside an inoperative stageloader/crusher and counteracted with active noise control. The ANC reduced the noise 3–5 dB (1–3 dBA). Important factors in the experiments included aspect ratio, cross-sectional area of the air space inside the machine, and change of coal height.
If practically implemented underground, the system potentially could reduce the workers’ noise dose and associated hearing loss.
131
EFFECTIVENESS OF ENGINEERING CONTROLS TO REDUCE OCCUPATIONAL NOISE EXPOSURE TO
SAWMILL WORKERS.
B. Takacs, D. Whiteman, K. Johnson, West Virginia University, Morgantown, WV.
West Virginia University Safety and Health Extension, WVUSHE, has had the opportunity to work with the sawmill industry in West Virginia through a small business outreach program. Initially, WVU was contacted to perform baseline monitoring for sawmills without noise monitoring data and to conduct follow-up evaluation for sawmills having a hearing conservation program. OSHA enacted a state emphasis program in and around the time of these noise surveys that required sawmills to implement engineering controls aimed at achieving at least a 3-dBA reduction in sawmill worker exposures.
WVUSHE provided general written recommendations and technical assistance to sawmills participating in the outreach program. This podium session or poster will share results of noise monitoring which includes dosimetry and sound levels collected pre- and post-engineering control implementation. Also, the types of materials and designs that were used to achieve feasible engineering controls will be highlighted. Other positive outcomes such as improvements in air quality and worker comfort are noted. In some instances, control implementation had to be modified several times to achieve desired reduction levels and lessons learned during this process will be shared. Workers’ use of hearing protection and results of audiometric testing will be discussed. Furthermore, this partnership demonstrates the utility of university—private industry working relationships aimed at improving worker health and comfort.
132
IMPLEMENTING TASK-BASED EXPOSURE ASSESSMENT FOR NOISE.
M. Waters, S. Brueck, M. Prince, D. Stancescu, CDC/NIOSH, Cincinnati, OH; S. Woskie, University of Massachusetts, Lowell, Lowell, MA.
WITHDRAWN.
133
EVALUATION OF NOISE EXPOSURE IN AN INDOOR SKATEPARK.
F. Akbar-Khanzadeh, R. England, Medical College of Ohio, Toledo, OH.
Exposure to noise in recreational facilities is widely accepted, and health professionals are rarely called to assess its magnitude and possible harmful effects. Indoor skateparks in particular may generate excessive noise because of their confined structural nature, possibly exposing users and employees to unacceptable levels of noise. This study used real-time sound level meters (Quest Models 400 and 500) to examine the extent of noise exposure at an indoor skatepark with wooden ramps. Noise sources included the activities of up to 25–30 individuals using skateboards, rollerblades, and bicycles on the ramps. At the facility’s front counter, where employees worked, minute-time-weighted average area noise exposure ranged from 50–95 dBA (mean ± SD of 65 ± 9 dBA; n = 88) with peak noise levels ranging from 101–145 dB (131 ± 7 dB). A skateboarder and a bystander (at a distance of 2 meters from the skateboarder) wore personal noise dosimeters concurrently for an extended period of time. The skateboarder’s minute-time-weighted average personal exposure ranged from 81–99 dBA (89 ± 3 dBA; n = 32) with peak noise levels ranging from 114–143 dB (131 ± 7 dB). The bystander’s minute-time-weighted average personal exposure ranged from 73–85 dBA (81 ± 3 dBA; n = 32) with peak noise levels ranging from 111–128 dB (118 ± 5 dB). The users of this facility were mostly children (ages ranging up to 21 years) and some adults including two employees. The noise was dominantly impulsive. According to World Health Organization recommendations, the peak sound pressure attributed to hearing impairment from impulse sounds in children is 120 dB, and for adults is 140 dB. The results of this study indicate that noise exposure levels in this facility exceed recommended limits. In order to protect participants, bystanders, and employees, noise levels should be controlled accordingly.
134
NOISE EXPOSURE AMONG EMPLOYEES WHO WORK IN DRINKING ESTABLISHMENTS THAT OFFER
LIVE MUSIC.
P. Prendergast, Environmental & Demolition Services Inc., Baltimore, MD; M. Gerke, Marshall University, Huntington, WV.
According to the U.S. Bureau of Labor Statistics, nationally, there are nearly 150,000 bartenders and nearly 80,000 waiters and waitresses who work in the job location category, drinking places: alcoholic beverages. Some “drinking places” offer some form of music as entertainment, many times in the form of live musicians. In venues where loud music is played, particularly live music, employees could be at risk for occupational noise exposure.
During the course of an environmental noise experiment, noise level samples were collected in and around a college drinking establishment. The establishment offered live music in the form of two five-person bands. The bands performed what would be classified as “rock and roll” music.
During a two-hour time frame, noise dosimeters were worn by two volunteers. These volunteers were stationed at specific locations within the establishment, but were free to move about the establishment. In addition, a hand-held sound meter set on the A-scale, slow response was used to collected samples from various specific locations within the establishment in 30-minute intervals.
The volunteer’s dosimeters recorded averages 99.1 dB and 98.6 dB with maximum levels of 118.1 dB and 121.1 dB, respectively. Recorded sound levels from 10 feet from the stage averaged 100.53 dB (107.8 dB maximum), 30 feet from the stage, 97.35 dB ( 106.7 dB maximum), and at the front door, 50 feet from the stage, 88.17 dB ( 99.3 dB maximum). Individuals who worked as bartenders, waitstaff, and security at this establishment could possibly be exposed to levels above the OSHA permissible noise-exposure level and would likely qualify to be included in an OSHA required hearing conservation program.
Individuals who work in establishments that routinely offer loud live music as entertainment should be made aware of the hazards associated with excessive noise exposure.
135
EXPOSURE ASSESSMENT OF A COMPLEX RF ENVIRONMENT.
J. Cardarelli, W. Lotz, C. Dowell, M. Finley, CDC/NIOSH, Cincinnati, OH.
The National Institute for Occupational Safety and Health was asked to provide technical assistance to the Kentucky Labor Cabinet in monitoring radiofrequency (RF) field strengths on a building roof that housed multiple antennas with various transmitting frequencies. Employees of a window-washing company expressed concern about their exposures to RF while conducting preparation activities on the roof.
Some of the problems encountered were: (1) a previous RF survey neither provided spatial-average measurements nor approximate work locations of the window washers; (2) power levels and transmitter locations had changed over time; and (3) determining the appropriate exposure limits that apply to this occupation. The challenges were: (1) selecting and using the appropriate instruments to account for the different frequencies and power outputs; (2) reconstructing the power output conditions on the day of the suspected overexposure; (3) implementing an appropriate spatial-averaging technique; and (4) determining the appropriate measurement locations.
The problems and challenges were resolved by: (1) interviewing the window washers about their equipment, tasks, work duration, and locations while on the roof; (2) working with the Kentucky Labor Cabinet, the building management, and transmitter owners to gain access and adjust transmission power levels; and (3) using an instrument with a shaped-frequency response probe designed to mirror the appropriate standard.
The need to characterize and assess potential exposures to nonionizing radiation is becoming more important with the increased use and advancement of wireless technology and capabilities. This work illustrates that workers in occupations outside the traditional fields in nonionizing radiation are also exposed to RF hazards. It also demonstrates the need to account for their potential exposures and to develop training specific to their needs. Exposure assessors will also be informed of the latest technology used to assess complex RF environments.
136
THE FREQUENCY ASPECT OF LOW FREQUENCY EMF MEASUREMENTS.
D. Baron, ETS-Lindgren, Cedar Park, TX.
Low frequency electric and magnetic field measurements can range from the low field levels observed near video display terminals to the substantial magnetic fields often found near induction heating equipment. Asking the proper questions before making measurements is essential to an accurate determination of potential hazards. The frequency of the measured field may have a substantial impact on the measured values because of the variation in safety limits, the characteristics of the measurement instrument, and the harmonic content of the field.
Two case studies are reviewed as examples of the effect of frequency on the recorded data and its impact on interpretation of the results. The need to properly identify the frequencies present and understand the interrelationship between the field environment and the sensing instruments used to gather the data is demonstrated. Ultimately the observed data is used to evaluate compliance with the selected safety guideline.
137
CRCPD AND AIHA—A PARTNERSHIP.
E. Bailey, R. Fraass, Conference of Radiation Control Program Directors, Frankfort, KY.
The Conference of Radiation Control Program Directors (CRCPD) is a 501(c)(3) nonprofit, nongovernmental, professional organization whose primary membership is comprised of radiation professionals in state and local government who regulate the use of radiation sources. However, any individual with an interest in radiation protection may become an affiliate or international member. This presentation will be a general overview of CRCPD including its objectives, organization, membership, annual meeting, publications, and extended discussion of its working groups. Those working groups operate under five Councils: Environmental Nuclear, General, Healing Arts, Suggested State Regulations, and Homeland Security. State regulations affect many AIHA customers and some AIHA members. The work of the Environmental Nuclear Council committees will be expanded upon as it may be of more direct interest to AIHA members. Those committees typically address issues of emergency response, source disposal, waste, radon, decontamination and decommissioning, laboratories, naturally occurring radioactive material, and monitoring. Another area of mutual interest is that of homeland security. State regulators and responders may be able to work with AIHA members to provide additional technically-trained monitors in the event of a radiological release. Routinely, AIHA members may contact CRCPD state members for technical assistance with any radiological issue. Finally, joint membership in both organizations and regional activities with the Health Physics Society, CRCPD, and AIHA will be recommended. Website: www.crcpd.org.
138
EMERGENCY PREPAREDNESS AND THE NUCLEAR REGULATORY COMMISSION.
K. Brock, U.S. Nuclear Regulatory Commission, Washington, DC.
NRC will provide an update on the emergency preparedness and incident response activities in the post September 11, 2001, environment. Included will be information about the restructuring of NRC to centralize safety, security, and emergency preparedness in one office, Nuclear Security and Incident Response; emergency preparedness in the news; enhancements to the NRC Incident Response Center; and NRC efforts to work with other Federal agencies in light of the new threat environment.
Posted May 30, 2005