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PubMed1986

The use of acoustical test fixtures for the measurement of hearing protector attenuation. Part II: Modeling the external ear, simulating bone conduction, and comparing test fixture and real-ear data.

This paper investigates two main features of the human head which influence the measured attenuation of circumaural and intraaural hearing protection devices (HPDs): the external ear and the different pathways of bone conduction. A theoretical model for the external ear shows that its influence on the insertion loss of HPDs, on the sensitivity level of headphones or earphones, and on the insertion gain of hearing aids, all can be described by one equation. While it is not necessary to simulate the eardrum impedance in order to measure the insertion loss of earmuffs and the sensitivity level of headphones with acoustical test fixtures (ATFs), the required accuracy of an ear simulator is more stringent when the same measurements are performed on intraaural devices. For the evaluation of HPDs, bone conduction plays an important role. We have developed a model to estimate HPD-dependent bone conduction effects. The model includes two bone conduction sources: one in the external ear and one in the middle ear. The model explains, for example, the occlusion effect of HPDs and the masking error at low frequencies due to physiological noise that arises when real-ear attenuation at threshold (REAT) measurements are made. Consequently, objectively measured insertion loss can now be used to predict REAT with improved accuracy. ATF and REAT data are compared using nine earmuffs and nine earplugs. In the majority of cases, the two sets of data agree well. Discrepancies are discussed.

Auditory Threshold↗
PubMed1990

Hearing conservation programs (HCPs): the effectiveness of one company's HCP in a 12-hr work shift environment.

An existing hearing conservation program (HCP), originally designed when an 8-hr work shift schedule was in effect, was evaluated at a plant site where a 12-hr work shift schedule is now utilized. The study included the following phases: a noise analysis of the work environment, HCP evaluation through the use of audiometric data base analysis (ADBA), applying ADBA procedures and a comparison of the shift in hearing threshold levels (HTLs) for the 8-hr and 12-hr work shifts, and an evaluation of the hearing protection devices (HPDs) being used at the facility over the 12-hr work shift by measuring temporary threshold shift (TTS). The mean measured employee time-weighted average (TWA) in the process area where the TTS study was conducted was 92 dBA. It was found that the existing HCP is at best marginal. The most likely causes of this less-than-desirable rating are inadequate audiometric testing procedures and inadequate HPD utilization. Furthermore, it was concluded that, at this time, the introduction of the 12-hr work shift has had no impact on the level of effectiveness of the HCP. In evaluating the three HPDs in use at the facility (3-M foam earplug, E-A-R foam earplug, and Bilsom Soft earplug), it was found that they all offered effective protection from noise at all audiometric test frequencies (0.5 to 6 kHz) except 0.5 kHz. All three HPDs exhibited TTS at 0.5 kHz with the TTS measured significant at the p less than 0.05 level for the E-A-R and 3-M wearer groups.

Audiometry↗
PubMed1986

The use of acoustical test fixtures for the measurement of hearing protector attenuation. Part I: Review of previous work and the design of an improved test fixture.

This paper gives a comprehensive progress report on the development of objective methods for measuring the attenuation of hearing protection devices (HPD's), and focuses on the use of acoustic test fixtures (ATF's), i.e., artificial heads. While there are many publications on ATF's for the evaluation of circumaural HPD's (earmuffs), only one serious attempt to construct an ATF for the evaluation of intra-aural HPD's (earplugs) could be found. Consequently, no ATF for testing earplugs has been standardized so far, while two standardized ATF's currently exist for testing earmuffs [see ANSI S3.19-1974 (1975) and ISO/DIS 6290 (1983)]. Both ATF's are suited, however, only for production testing and are not designed for HPD-type testing. It is believed that both ATF's do not provide sufficiently high accuracy for HPD-type testing. A new ATF with appropriate circumaural and intra-aural flesh simulations was constructed, including a suitable ear simulator and a cast of an average pinna. Objectives for design and construction of the new ATF are discussed. The effect of using artificial flesh on the insertion loss of earmuffs (max. 5 dB at 125 and/or 250 Hz) and the effect of using a pinna (max. 12 dB lower insertion loss at 2 kHz) were evaluated.

Auditory Threshold↗
PubMedDate not supplied

Prevention of work related injuries: a look at eye protection use and suggested prevention strategies.

Eye injuries account for 6% of all national injuries, with 60% of those injured professing to not having worn any eye protection. Most injuries (70%) are from flying objects that come around the front of a flat "eyeglass type" personal protective device. Blindness prevention include educating managers and employees, and purchasing and distributing effective eye wear protection.

Eye Injuries↗
PubMed2005

The effectiveness of hearing protection among construction workers.

Effective hearing conservation programs in the construction industry are rare. Where programs are present, they often rely on workers' use of hearing protection devices (HPDs) rather than on exposure controls to reduce noise exposure levels. Dependence on HPDs for protection from high noise is problematic, as the protection provided by the HPD depends on both the HPD's attenuation level and the time the HPD is used. This article presents an analysis of data on noise exposure and hearing protection among construction workers drawn from several large datasets covering nine construction trades. A unique combination of 1-min dosimetry noise exposure levels and simultaneous self-reported use of HPDs was evaluated, as were occupational and nonoccupational HPD use data collected by questionnaire as part of a longitudinal study of noise exposure and hearing loss among apprentices. Direct measurements of HPD attenuation were also made on workers at their work site. The workers assessed in this study were found to use hearing protection less than one-quarter of the time that they were exposed above 85 dBA. Workers who reported always using HPDs in high noise on questionnaires were found to wear them only one-third of the time their exposures exceeded 85 dBA. Workers' self-reported use of HPDs during most noisy nonoccupational activities was also found to be low. Direct attenuation measurements found that workers were able to achieve more than 50% of the rated attenuation of their HPD on average, but that the variability in achieved attenuation was large. When the measured HPD attenuation levels and use time data were combined, the effective protection afforded by HPDs was less than 3 dB, a negligible amount given the high exposure levels associated with construction work. However, there was substantial variation in effective protection among the different trades assessed. These results demonstrate the need for better hearing conservation programs and expanded noise control efforts in the construction industry.

Cohort Studies↗
PubMedDate not supplied

Understanding barriers to preventive health actions for occupational noise-induced hearing loss.

A theoretically based formative evaluation was conducted with coal miners in the Appalachian Mountains who were at high risk for noise-induced hearing loss (NIHL). The results of four focus groups indicate that despite high levels of knowledge, strong perceived severity of negative consequences, and strong perceived susceptibility to hearing loss, two main categories of barriers (environmental and individual) keep coal miners from using their hearing protection devices (HPD). Further analysis suggests that the environmental factors, rather than individual variables, more strongly influence decisions against protective actions. Recommendations and practical implications are offered.

Adult↗
PubMed2000

[Secondary ionizing radiation generated by digital and analog coronary cineangiographic equipment: influence of external systems of radiologic protection].

BACKGROUND: Exposure to ionizing radiation is a known hazard of radiological procedures. AIM: To compare the emission of secondary ionizing radiation from two coronary angiographic equipment, one with digital and the other with analog image generation. To evaluate the effectiveness of external radiological protection devices. MATERIAL AND METHODS: Environmental and fluoroscopy generated radiation in the cephalic region of the patient was measured during diagnostic coronary angiographies. Ionizing radiation generated in anterior left oblique projection (ALO) and in anterior right oblique projection (ARO) were measured with and without leaded protections. In 19 patients (group 1), a digital equipment was used and in 21 (group 2), an analog equipment. RESULTS: Header radiation for groups 1 and 2 was 1194 +/- 337 and 364 +/- 222 microGray/h respectively (p < 0.001). During fluoroscopy and with leaded protection generated radiation for groups 1 and 2 was 612 +/- 947 and 70 +/- 61 microGray/h respectively (p < 0.001). For ALO projection, generated radiation for groups 1 and 2 was 105 +/- 47 and 71 +/- 192 microGray/h respectively (p < 0.001). During filming the radiation for ALO projection for groups 1 and 2 was 7252 +/- 9569 and 1671 +/- 2038 microGray/h respectively (p = 0.03). Out of the protection zone, registered radiation during fluoroscopy for groups 1 and 2 was 2800 +/- 1741 and 1318 +/- 954 microGray/h respectively (p < 0.001); during filming, the figures were 15,500 +/- 5840 and 18,961 +/- 10,599 microGray/h respectively (NS). CONCLUSIONS: Digital radiological equipment has a lower level of ionizing radiation emission than the analog equipment.

Adult↗
PubMed1996

Neck injuries from skate blades in ice hockey: a report of three cases.

This article describes three neck slash injuries in amateur ice hockey players, with a fatal outcome in two. One player died of asphyxation secondary to hemorrhage into the respiratory passage, but the other died of hemorrhage from the main blood vessels in the neck, severed by the skate blade. All three were not wearing any neck protecting device. Neck slash injury from skate blades, as a preventable sports-related injury, and the need for neck protective equipment in preventing such injuries are discussed.

Adolescent↗
PubMed2001

Proposal for an approach with default values for the protection offered by PPE, under European new or existing substance regulations.

Introduction of personal protective equipment (PPE) in the process of quantitative exposure and risk assessment should be addressed carefully. PPE which have been designed and manufactured according to CE-criteria and have proved to pass relevant test criteria, can be classified as "proper functioning". However, test criteria for PPE are not equal to levels of protection which can be achieved in the workplace, because actual workplace exposure scenarios, fit, maintenance and storage may differ substantially from the test conditions. The proper use of PPE is related to issues which form a part of a PPE-programme. Such a programme should be implemented in a company to ensure selection of proper PPE and information, training and instruction of employees how to wear PPE properly. Assigned protection factors (APFs) for different designs of respiratory protective devices (RPD) have been introduced to quantify effectiveness of RPD in the workplace. Similar APFs are proposed for dermal protection (gloves and clothing). In general biological monitoring studies show lower reduction of internal exposure than estimated by reduction of external exposure. Therefore, conservative estimates of protection by PPE, i.e. the lowest APFs, are proposed for risk assessment purposes if "proper use of proper functioning" PPE as part of a PPE-programme cannot be demonstrated.

Accidents, Occupational↗
PubMed2001

Isolating the auditory system from acoustic noise during functional magnetic resonance imaging: examination of noise conduction through the ear canal, head, and body.

Approaches were examined for reducing acoustic noise levels heard by subjects during functional magnetic resonance imaging (fMRI), a technique for localizing brain activation in humans. Specifically, it was examined whether a device for isolating the head and ear canal from sound (a "helmet") could add to the isolation provided by conventional hearing protection devices (i.e., earmuffs and earplugs). Both subjective attenuation (the difference in hearing threshold with versus without isolation devices in place) and objective attenuation (difference in ear-canal sound pressure) were measured. In the frequency range of the most intense fMRI noise (1-1.4 kHz), a helmet, earmuffs, and earplugs used together attenuated perceived sound by 55-63 dB, whereas the attenuation provided by the conventional devices alone was substantially less: 30-37 dB for earmuffs, 25-28 dB for earplugs, and 39-41 dB for earmuffs and earplugs used together. The data enabled the clarification of the relative importance of ear canal, head, and body conduction routes to the cochlea under different conditions: At low frequencies (< or =500 Hz), the ear canal was the dominant route of sound conduction to the cochlea for all of the device combinations considered. At higher frequencies (>500 Hz), the ear canal was the dominant route when either earmuffs or earplugs were worn. However, the dominant route of sound conduction was through the head when both earmuffs and earplugs were worn, through both ear canal and body when a helmet and earmuffs were worn, and through the body when a helmet, earmuffs, and earplugs were worn. It is estimated that a helmet, earmuffs, and earplugs together will reduce the most intense fMRI noise levels experienced by a subject to 60-65 dB SPL. Even greater reductions in noise should be achievable by isolating the body from the surrounding noise field.

Adult↗
PubMed1995

Safelon--a new device to reduce needle-stick injuries during intravenous cannulation.

A prospective evaluation was performed to assess the efficacy and ease of use of a novel self-sheathing intravenous cannula with needle protection device (Safelon). Use of the device did not require significant change to the normal cannulation technique. Blood splashes during insertion and the risk of needle-stick injury were reduced.

Catheterization, Peripheral↗
PubMed1995

Suffocation from use of modified gas mask.

We report a case of suffocation caused by use of a gas mask modified by the attachment of a plastic bag with evidence of halothane inhalation. Gas masks and plastic bags are sometimes used to aid in the inhalation of volatile substances. Improper use or modification of gas masks or other respiratory protection devices may result in asphyxial death.

Adult↗
PubMedDate not supplied

Principles of respiratory protection.

This review describes the various types of respiratory protective devices used in Israel during the Persian Gulf war, and summarizes the relevant physiological concepts of respiratory protection. Physiological principles of modern devices with powered air supply are discussed in detail. Our experience may be useful in the evaluation of new respirators and in finding solutions for problematic subpopulations.

Adult↗
PubMed1983

Evaluation of radiation exposures to personnel in fluoroscopic X-ray facilities.

Personnel monitoring data reported in the literature at selected monitoring sites for personnel working in fluoroscopic X-ray facilities are analyzed. The results are used to attempt to more realistically estimate the potential organ doses for X-ray personnel wearing protective devices such as lead aprons and protective eyeglasses when these personnel wear only one dosimeter positioned outside the apron at the collar. The applicability of these results to current U.S. dose standards and the ICRP weighted dose equivalent concept is discussed.

Fluoroscopy↗
PubMed1997

[Study on effects of combined hearing protector on communication quality and noise protection].

To study the communication quality and the protection effects of single protector and the combined ones, sound attenuation experiments and the communication experiments were conducted in 14 male subjects. The results showed that the sound attenuation of combined protectors were 13 dB or 6dB more than that of single earplug or earmuff respectively, and combined protectors could avoid sound attenuation caused by the harmonics on some frequency bands in single one. After combined usage, the single protector reduced the distortion which came from the overload of hearing organs and maintained the communication quality. The combined protector is an effective hearing protection device in high noise environment in aerospace field.

Communication↗
PubMed2004

Using the extended parallel process model to prevent noise-induced hearing loss among coal miners in Appalachia.

Occupational noise-induced hearing loss is the second most self-reported occupational illness or injury in the United States. Among coal miners, more than 90% of the population reports a hearing deficit by age 55. In this formative evaluation, focus groups were conducted with coal miners in Appalachia to ascertain whether miners perceive hearing loss as a major health risk and if so, what would motivate the consistent wearing of hearing protection devices (HPDs). The theoretical framework of the Extended Parallel Process Model was used to identify the miners' knowledge, attitudes, beliefs, and current behaviors regarding hearing protection. Focus group participants had strong perceived severity and varying levels of perceived susceptibility to hearing loss. Various barriers significantly reduced the self-efficacy and the response efficacy of using hearing protection.

Adult↗
PubMed2006

Effect of respirators equipped with particle or particle-and-gas filters during exposure in a pig confinement building.

OBJECTIVES: This study compared the protective effect of two respiratory protection devices during exposure in a pig confinement building. METHODS: Thirty-six healthy persons were exposed for 3 hours in the building, 12 without any protection, 12 with a particle-filter mask, and 12 with a mask filtering both particles and gases. Symptoms, body temperature, nasal lavage fluid, exhaled nitric oxide, and bronchial responsiveness to methacholine were assessed before and after the exposure. Pre- and postexposure urine and blood samples were collected. RESULTS: After the exposure, the participants with respirators reported fewer symptoms than those without. Wearing a mask also reduced the inflammatory response assessed with nasal lavage (cell concentration, interleukins 6 and 8) and peripheral blood (cell number). Lung function was significantly impaired only in the unprotected group; postexposure vital capacity and forced expiratory volume in 1 second showed a decrease of 3-4% from the preexposure levels (P=0.006 and P=0.002, respectively). Bronchial responsiveness (P<0.01) and body temperature (P<0.001) increased similarly in the three groups. Bronchial responsiveness to methacholine increased 2.7, 2.4, and 2.1 doubling concentration steps for those unprotected, those using a particle-filter mask, and those using a mask with particle and gas filters, respectively. The prostaglandin D2 metabolite, 9a, 11b-PGF2 increased significantly (P=0.003) only in those unprotected. CONCLUSIONS: Wearing a respirator in a pig confinement building reduces the inflammatory reaction but does not influence the increase in bronchial responsiveness, with no difference between the use of a particle-filter mask or a mask with a particle-gas filter combination.

Adult↗