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PubMed1977

Odor detection and respirator cartridge replacement.

If the odor threshold of a compound is greater than its TLV, overexposure of a respirator user is possible since breakthrough may not be detected. Odor threshold data are assembled for a number of different materials and compared to their TLV's. Use practices are recommended for chemical cartidge respirators for various grouping of compounds, based on their odor threshold to TLV ratio.

Alcohols↗
PubMed1995

Respirators, recommendations, and regulations: the controversy surrounding protection of health care workers from tuberculosis.

Recent nosocomial outbreaks of tuberculosis have increased concern about the occupational acquisition of tuberculosis by health care workers. The Centers for Disease Control and Prevention (CDC), Department of Health and Human Services, and the Occupational Safety and Health Administration, Department of Labor, have issued recommendations and regulations in an effort to decrease health care workers' risk for exposure to patients with infectious tuberculosis. Within the CDC, the National Center for Infectious Diseases, the National Center for Prevention Services, and the National Institute for Occupational Safety and Health collaborated to produce the 1994 Guidelines for Preventing the Transmission of Tuberculosis in Health-Care Facilities. As stated in the Draft Guidelines, the major components of health care worker protection from Mycobacterium tuberculosis infection include administration or source controls, engineering controls, and respiratory protective devices. We review the evolution of the seemingly conflicting recommendations for respiratory protective devices made by these Centers of the CDC and explain how the recommendations in the current CDC Guidelines were reached.

Centers for Disease Control and Prevention, U.S.↗
PubMed1997

National Institute for Occupational Safety and Health; certification of respiratory devices used to protect workers in hazardous environments--NIOSH. Notice of priorities for rulemaking.

In response to public comments received from its May 16, 1996, request (61 FR 24740), NIOSH is announcing the intended priority order for the development of the next proposed rule amendments (modules) to the current NIOSH procedures for certifying respiratory devices used to protect workers in hazardous environments. The priority order is based on the comments and data in the public record. The priority order of the planned modules is provided to help the respirator community plan for potential changes.

Humans↗
PubMed2000

Medical evaluation for respirator use.

The purpose of a respirator is to prevent the inhalation of harmful airborne substances or to provide a source of respirable air when breathing in oxygen-deficient atmospheres. For a physician to recommend the use of respirator, general background information on respiratory-protective devices is required. The first part of this clinical practice review describes the general aspects of industrial hygiene, respirators and a respirator-certification program. The second part addresses matters related to medical certification for respirator use. Medical certification for respirators is an important part of the activities of the occupational physician. To determine whether a worker is able to tolerate the added strain of a respiratory protective device is a complex process in which factors such as fitness for work, health of the individual, characteristics of the work itself, and the properties, type, and requirements of the respiratory protective device, have to be considered. Medical certification is of utmost importance for respirator use, and it should be viewed as an element in a comprehensive respiratory protection program. A comprehensive program is the key element in affording the workers' effective respiratory protection once the initial steps of the hierarchy of methods of hazard control have proved insufficient or infeasible. As a result, the need for the industrial hygiene/safety officer, the worker, the employer and the medical professional to work as a team is much more than in any other field of occupational medicine--a necessary requirement for making the right decision.

Decision Making↗
PubMedDate not supplied

Using a mathematical model to evaluate the efficacy of TB control measures.

We evaluated the efficacy of recommended tuberculosis (TB) infection control measures by using a deterministic mathematical model for airborne contagion. We examined the percentage of purified protein derivative conversions under various exposure conditions, environmental controlstrategies, and respiratory protective devices. We conclude that environmental control cannot eliminate the risk for TB transmission during high-risk procedures; respiratory protective devices, and particularly high-efficiency particulate air masks, may provide nearly complete protection if used with air filtration or ultraviolet irradiation. Nevertheless, the efficiency of these control measures decreases as the infectivity of the source case increases. Therefore, administrative control measures (e.g., indentifying and isolating patients with infectious TB) are the most effective because they substantially reduce the rate of infection.

Cross Infection↗
PubMed1979

The physiological consequences of wearing industrial respirators: a review.

The American Industrial Hygiene Association (AIHA) and American Conference of Govermental Industrial Hygienists (ACGIH) Respiratory Protective Devices Manual, published in 1963, has as its primary source of physiological background the work of Silverman and co-workers performed during World War II. The adoption of permanent OSHA standards governing work tasks requiring workers to use respirators has created a need for further evaluation of the physiological effects of wearing a respirator. This review was undertaken to meet the need of an in-depth evaluation of the currently available psychophysiological data. It was concluded that it was of the utmost importance to develop a physiological and psychological medical screening examination to determine the capability of the worker to use a respirator.

Body Temperature Regulation↗
PubMed2002

Airways inflammation after exposure in a swine confinement building during cleaning procedure.

BACKGROUND: Healthy volunteers exposed for 3 hr during weighing of pigs develop an airway inflammation characterized by a massive influx of neutrophilic granulocytes in the upper and lower airways and increased bronchial responsiveness to methacholine. The purpose of the present study was to investigate health effects from exposure during cleaning of the swine confinement building and to evaluate the effect of a respiratory protection device. METHODS: Sixteen subjects were exposed for 3 hr during cleaning of a swine confinement room with a high-pressure cleaner. Seven out of sixteen subjects were equipped with a mask during exposure. RESULTS: The bronchial responsiveness increased in all subjects following exposure, significantly more in the group exposed without a mask (P < 0.05). The cell concentration (mainly neutrophilic granulocytes) in nasal lavage fluid as well as the concentration of interleukin-8, increased significantly only in those subjects exposed without a respiratory protection device. In peripheral blood, an increase of neutrophilic granulocytes was observed in both groups, although it was significantly higher in the group without mask (P < 0.05). The inhalable dust level was 0.94 (0.74 - 1.55) mg/m(3) and respirable dust 0.56 (0.51-0.63) mg/m(3). CONCLUSION: Exposure to dust aerosols during the cleaning of the interior of a swine confinement building induces increased bronchial responsiveness and an acute inflammatory reaction in the upper airways. The use of a mask attenuated but did not abolish the inflammatory response. This suggests that gases and/or ultrafine particles in this environment could be important factors in the development of increased bronchial responsiveness.

Animal Husbandry↗
PubMed1999

Trends in compliance with the guidelines for preventing the transmission of Mycobacterium tuberculosis among New Jersey hospitals, 1989 to 1996.

OBJECTIVE: To determine trends in compliance with the guidelines for preventing the transmission of Mycobacterium tuberculosis in healthcare facilities among New Jersey hospitals from 1989 through 1996. DESIGN: A voluntary questionnaire was sent to all 96 New Jersey hospitals in 1992. The 53 that responded were resurveyed in 1996. RESULTS: Of the 96 hospitals surveyed in 1992, 53 (55%) returned a completed questionnaire; 33 (64%) were community, nonteaching hospitals. In 1991, patients with tuberculosis (TB) were admitted at 38 (72%) of 53 hospitals, and from 1989 through 1991, patients with multidrug-resistant (MDR) TB were admitted at 15 (29%) of 52 hospitals. Twenty-nine (57%) of 51 reported having rooms meeting the Centers for Disease Control and Prevention (CDC) criteria for acid-fast bacilli (AFB) isolation. A nonfitted surgical mask was used as a respiratory protective device by healthcare workers (HCWs) at 28 (55%) of 51 hospitals. Attending physicians were included in tuberculin skin-testing (TST) programs at 5 (11%) of 45 hospitals. In the 1996 resurvey, 48 (94%) of 53 surveyed hospitals returned a completed questionnaire; 34 (81%) of 42 had TB patient admissions, and 4 (9%) of 43 had MDR TB patient admissions in 1996. Forty-five (96%) of 47 reported having rooms that met CDC criteria for AFB isolation. N95 respiratory devices were used by HCWs at 45 (94%) of 48 hospitals. Attending physicians were included in the TST programs at 22 (54%) of 41 hospitals. CONCLUSION: New Jersey hospitals have made improvements in availability of AFB isolation rooms, use of proper respiratory protective devices, and expansion of TST programs for HCWs from 1989 through 1996.

Cross Infection↗
PubMed1998

Are US hospitals making progress in implementing guidelines for prevention of Mycobacterium tuberculosis transmission?

BACKGROUND: Outbreaks of tuberculosis (TB) in hospitals have occurred when the Centers for Disease Control and Prevention (CDC) guideline recommendations for preventing the transmission of Mycobacterium tuberculosis were not fully implemented. OBJECTIVE: To determine whether US hospitals are making progress in implementing the CDC guidelines for preventing TB. METHODS: In 1992, we surveyed all public (city, county, Veterans Affairs, and primary medical school-affiliated) US hospitals (n = 632) and 444 (20%) random samples of all private hospitals with 100 beds or more. In 1996, we resurveyed 136 random samples (50%) of all 1992 respondent hospitals with 6 or more TB admissions in 1991. RESULTS: Of the 1076 hospitals surveyed in 1992, 763 (71%) respondents returned a completed questionnaire. Among these, 536 (71%) of 755 reported having rooms that met CDC criteria for acid-fast bacilli isolation, ie, negative air pressure, 6 or more air exchanges per hour, and air directly vented to the outside. The predominant respiratory protective device for health care workers was nonfitted surgical mask and attending physicians were infrequently (50%) included in tuberculin skin-testing programs. In the 1996 resurvey, 103 (76%) of 136 respondents returned a completed questionnaire. Of these, 99 (96%) reported having rooms that met CDC criteria for acid-fast bacilli isolation. The N95 respiratory protective devices were predominantly used by health care workers, and attending physicians were increasingly (69%) included in the hospitals' tuberculin skin-testing programs. CONCLUSIONS: Most US hospitals are making progress in the implementation of CDC guidelines for preventing the transmission of M tuberculosis.

Centers for Disease Control and Prevention, U.S.↗
PubMed2004

Influence of inspiratory resistance on performance during graded exercise tests on a cycle ergometer.

Due to more stringent requirements to protect personnel against hazardous gasses, the inspiratory resistance of the present generation of respiratory protective devices tends to increase. Therefore an important question is to what extent inspiratory resistance may increase without giving problems during physical work. In this study the effects of three levels (0.24; 1.4 and 8.3 kPa s l(-1)) of inspiratory resistance were tested on maximal voluntary performance. Nine male subjects performed a graded exercise test on a cycle ergometer with and without these three levels of inspiratory resistance. Oxygen consumption, heart rate, time to exhaustion and external work were measured. The results of these experiments showed that increasing inspiratory resistance led to a reduction of time to exhaustion (TTE) on a graded exercise test(GXT). Without inspiratory resistance the mean TTE was 11.9 min, the three levels of resistance gave the following mean TTE's: 10.7, 7.8 and 2.7 min. This study showed that TTE on a GXT can be predicted when physical fitness (VO2-max) of the subject and inspiratory resistance are known. The metabolic rate of the subjects was higher with inspiratory resistance, but no differences were found between the three selected inspiratory loads. Other breathing parameters as minute ventilation, tidal volume, expiration time and breathing frequency showed no or minor differences between the inspiratory resistances. The most important conclusion of these experiments is that the overall workload increases due to an increase in inspiratory resistance by wearing respiratory protective devices.

Adolescent↗
PubMed2006

Do N95 respirators provide 95% protection level against airborne viruses, and how adequate are surgical masks?

BACKGROUND: Respiratory protection devices are used to protect the wearers from inhaling particles suspended in the air. Filtering face piece respirators are usually tested utilizing nonbiologic particles, whereas their use often aims at reducing exposure to biologic aerosols, including infectious agents such as viruses and bacteria. METHODS: The performance of 2 types of N95 half-mask, filtering face piece respirators and 2 types of surgical masks were determined. The collection efficiency of these respiratory protection devices was investigated using MS2 virus (a nonharmful simulant of several pathogens). The virions were detected in the particle size range of 10 to 80 nm. RESULTS: The results indicate that the penetration of virions through the National Institute for Occupational Safety and Health (NIOSH)-certified N95 respirators can exceed an expected level of 5%. As anticipated, the tested surgical masks showed a much higher particle penetration because they are known to be less efficient than the N95 respirators. The 2 surgical masks, which originated from the same manufacturer, showed tremendously different penetration levels of the MS2 virions: 20.5% and 84.5%, respectively, at an inhalation flow rate of 85 L/min. CONCLUSION: The N95 filtering face piece respirators may not provide the expected protection level against small virions. Some surgical masks may let a significant fraction of airborne viruses penetrate through their filters, providing very low protection against aerosolized infectious agents in the size range of 10 to 80 nm. It should be noted that the surgical masks are primarily designed to protect the environment from the wearer, whereas the respirators are supposed to protect the wearer from the environment.

Air Microbiology↗