Journal of the International Society for Respiratory Protection最新文献

Long term storage of personal protective equipment (PPE) in stockpiles is increasingly common in preparation for use during public health emergency responses. Confidence in PPE requires an understanding of the impact of time in storage on all aspects of PPE effectiveness, including protection against inward leakage. Disposable N95 filtering facepiece respirators (FFR) typically rely upon inexpensive elastomeric head straps to provide an effective seal between the filter body and the wearer's face. Annual fit testing provides a measure of assurance that a model fresh from the manufacturer will prove effective, but seal quality may degrade during long term storage. This study examines the stability of a s election of polyisoprene elastomer straps taken from various ages of common N95 FFRs. The tension of the straps at a predetermined strain of 150% was found to differ according to age for one respirator model, though whether due to age or due to manufacturing variations could not be determined. The straps from one manufacturer were found to have notable variation in length, indicating that minor variations in strap tensile properties may not result in significant differences in respirator seal quality. Based on our observations, prolonged storage may affect the tensile properties of headstraps for some models of N95.

Objective: Loose-fitting powered air-purifying respirators (PAPRs) are increasingly being used in healthcare. NIOSH has previously used advanced manikin headforms to develop methods to evaluate filtering facepiece respirator fit; research has now begun to develop methods to evaluate PAPR performance using headforms. This preliminary study investigated the performance of PAPRs at different work rates to support development of a manikin-based test method.

Methods: Manikin penetration factors (mPF) of three models of loose-fitting PAPRs were measured at four different work rates (REST: 11 Lpm, LOW: 25 Lpm, MODERATE: 48 Lpm, and HIGH: 88 Lpm) using a medium-sized NIOSH static advanced headform mounted onto a torso. In-mask differential pressure was monitored throughout each test. Two condensation particle counters were used to measure the sodium chloride aerosol concentrations in the test chamber and also inside the PAPR facepiece over a 2-minute sample period. Two test system configurations were evaluated for returning air to the headform in the exhalation cycle (filtered and unfiltered). Geometric mean (GM) and 5th percentile mPFs for each model/work rate combination were computed. Analysis of variance tests were used to assess the variables affecting mPF.

Results: PAPR model, work rate, and test configuration significantly affected PAPR performance. PAPR airflow rates for the three models were approximately 185, 210, and 235 Lpm. All models achieved GM mPFs and 5^th percentile mPFs greater than their designated Occupational Safety and Health Administration assigned protection factors despite negative minimum pressures observed for some work rate/model combinations.

Conclusions: PAPR model, work rate, and test configuration affect PAPR performance. Advanced headforms have potential for assessing PAPR performance once test methods can be matured. A manikin-based inward leakage test method for PAPRs can be further developed using the knowledge gained from this study. Future studies should vary PAPR airflow rate to better understand the effects on performance. Additional future research is needed to evaluate the correlation of PAPR performance using advanced headforms to the performance measured with human subjects.

The U.S. Bureau of Mines (USBM) was established on July 1, 1910 with a mission to address the previous decade's coal mine fatality incidence rate of greater than 2,000 annually. The need for federal government involvement to assure dependable and safe mine rescue respirators was recognized by the USBM with the first respirator approval being issued in 1919. Prior to this, some occupations exposed individuals to inhalation hazards. Firefighters, in particular, had a critical need of respiratory protection. This article provides a brief summary of pre-World War I (WWI) (1914 to 1918) respiratory protection for firefighters based largely on the work of Bruce J. Held. Also discussed is the then newly established United States Bureau of Mines' (USBM) role with the U.S. War Department during WWI for protection against chemical warfare agents.

This article describes several aspects of oxygen (O₂) deficiency with an emphasis on respirator programs and respirator selection. The Occupational Safety and Health Administration's (OSHA) 29 CFR 1910.134 and ANSI/ASSE Z88.2-2015 (Z88.2) have much in common. However, their exposure criteria and terminology used for describing levels of O₂-deficiency and the approaches to assessing O₂-deficiency differ. These differences can have a significant impact on an employer's respirator program and respirator selections for workplaces at altitudes above sea level. Under certain circumstances, Z88.2 leads to a more conservative respirator selection than OSHA because its O₂-deficiency criteria and hazard assessment approach relies directly on partial pressure of oxygen (PO₂) at all altitudes. Z88.2 defines an O₂-deficient atmosphere as either immediately dangerous to life or health (IDLH), or non-IDLH based on the atmosphere's PO₂ and defines respirator selection for these two O₂-deficient atmospheres. Unlike Z88.2, OSHA does not directly access the biologically significant aspect of an atmosphere's PO₂ in its hazard assessment. OSHA defines an O₂-deficient atmosphere based upon a percentage of oxygen. OSHA does not use the term "O₂-deficient IDLH"; however, OSHA considers any atmosphere with less than 19.5% O₂ as IDLH and defines respirator selection for IDLH atmospheres. Although OSHA does not use the term "PO₂" in their respirator standard, OSHA's exceptions to O₂-deficient IDLH respirator selection policy are based on PO₂ altitude-adjusted, O₂ percentage criteria. This article provides descriptions of OSHA and Z88.2 requirements to evaluate workplace oxygen deficiency, their approaches to O₂-deficiency hazard assessment, and describes their significance on respirator programs and selections. Alternative solutions to wearing respirators for protection against O₂-deficiency resulting solely from high altitudes are also discussed. Selection and implementation of alternative solutions by the employer and their Physician or other Licensed Health Care Professional (PLHCP) are not covered by either respirator standard. Appendix A provides information about the physiological effect of wearing respirators and the mechanics of respiration, which is an important consideration in lower O₂ atmospheres.

The goal of this investigation was to evaluate the physiologic stresses of powered air-purifying respirators (PAPRs) used by workers in many industries (e.g., health care, automobile repair, public safety, building trades, etc.) during rest and three levels of energy expenditure. Twelve men and twelve women wore one tight-fitting and three loose-fitting PAPRs at rest (REST) and while walking for four minutes at oxygen consumption (V̇O₂) rates of 1.0 l·min^-1(LOW), 2.0 l·min^-1 (MODERATE), and 3.0 l·min^-1 or maximum (HIGH). Minimum inhaled carbon dioxide concentration (F_ICO₂), maximum inhaled oxygen concentration (F_IO₂), peak inhalation pressure, and end inhalation temperature were measured continuously breath-by-breath. Repeated measures analysis of variance found that neither the main effect of gender, nor any interactions involving gender were significant. The highest minimum F_ICO₂ among PAPRs occurred for MODERATE and HIGH energy expenditures while wearing the loose-fitting PAPR with the largest dead space. The lowest maximum F_IO₂ was observed during HIGH intensity energy expenditure also for the loose-fitting PAPR with the largest dead space. Among all PAPR models, peak inhalation pressures were negative at V̇O₂ > LOW, suggesting that peak inhalation flow was greater than blower flow. Results using the variables reported here suggest that PAPRs used at various levels of energy expenditure may be tolerated among healthy workers. Further research is needed to determine the source of supplemented air when inhalation flow exceeds blower flow.

In the U.S., respiratory protection is broadly supported by a system of coordinated efforts among governmental organizations, professional associations, researchers, industrial hygienists, manufacturers, and others who produce knowledge, best practice guidance, standards, regulations, technologies, and products to assure workers can be effectively protected. Ultimately, the work of these partners is applied by employers in establishing and implementing an effective ANSI/ASSE Z88.2-2015 conforming respirator program. This article describes key partners and their activities and/or responsibilities to assure an effective respirator program.

Information that details use and supply of respirators in acute care hospitals is vital to prevent disease transmission, assure the safety of health care personnel, and inform national guidelines and regulations.

Objective: To develop measures of respirator use and supply in the acute care hospital setting to aid evaluation of respirator programs, allow benchmarking among hospitals, and serve as a foundation for national surveillance to enhance effective Personal Protective Equipment (PPE) use and management.

Methods: We identified existing regulations and guidelines that govern respirator use and supply at Vanderbilt University Medical Center (VUMC). Related routine and emergency hospital practices were documented through an investigation of hospital administrative policies, protocols, and programs. Respirator dependent practices were categorized based on hospital workflow: Prevention (preparation), patient care (response), and infection surveillance (outcomes). Associated data in information systems were extracted and their quality evaluated. Finally, measures representing major factors and components of respirator use and supply were developed.

Results: Various directives affecting multiple stakeholders govern respirator use and supply in hospitals. Forty-seven primary and secondary measures representing factors of respirator use and supply in the acute care hospital setting were derived from existing information systems associated with the implementation of these directives.

Conclusion: Adequate PPE supply and effective use that limit disease transmission and protect health care personnel are dependent on multiple factors associated with routine and emergency hospital practices. We developed forty-seven measures that may serve as the basis for a national PPE surveillance system, beginning with standardized measures of respirator use and supply for collection across different hospital types, sizes, and locations to inform hospitals, government agencies, manufacturers, and distributors. Despite involvement of multiple hospital stakeholders, regulatory guidance prescribes workplace practices that are likely to result in similar workflows across hospitals. Future work will explore the feasibility of implementing the collection and reporting of standardized measures in multiple facilities.

National Institute for Occupational Safety and Health (NIOSH)-approved N95 filtering-facepiece respirators (FFR) are currently stockpiled by the U.S. Centers for Disease Control and Prevention (CDC) for emergency deployment to healthcare facilities in the event of a widespread emergency such as an influenza pandemic. This study assessed the fit of N95 FFRs purchased for the CDC Strategic National Stockpile. The study addresses the question of whether the fit achieved by specific respirator sizes relates to facial size categories as defined by two NIOSH fit test panels. Fit test data were analyzed from 229 test subjects who performed a nine-donning fit test on seven N95 FFR models using a quantitative fit test protocol. An initial respirator model selection process was used to determine if the subject could achieve an adequate fit on a particular model; subjects then tested the adequately fitting model for the nine-donning fit test. Only data for models which provided an adequate initial fit (through the model selection process) for a subject were analyzed for this study. For the nine-donning fit test, six of the seven respirator models accommodated the fit of subjects (as indicated by geometric mean fit factor > 100) for not only the intended NIOSH bivariate and PCA panel sizes corresponding to the respirator size, but also for other panel sizes which were tested for each model. The model which showed poor performance may not be accurately represented because only two subjects passed the initial selection criteria to use this model. Findings are supportive of the current selection of facial dimensions for the new NIOSH panels. The various FFR models selected for the CDC Strategic National Stockpile provide a range of sizing options to fit a variety of facial sizes.

Research on influenza viruses regarding transmission and survival has surged in the recent years due to infectious emerging strains and outbreaks such as the 2009 Influenza A (H1N1) pandemic. MS2 coliphage has been applied as a surrogate for pathogenic respiratory viruses, such as influenza, as it's safe for personnel to handle and requires less time and labor to measure virus infectivity. However, direct comparisons to determine the effectiveness of coliphage as a surrogate for influenza virus regarding droplet persistence on personal protective equipment such as N95 filtering facepiece respirators (FFRs) are lacking. Persistence of viral droplets deposited on FFRs in healthcare settings is important to discern due to the potential risk of infection via indirect fomite transmission. The objective of this study was to determine if MS2 coliphage could be applied as a surrogate for influenza A viruses for studying persistence when applied to the FFRs as a droplet. The persistence of MS2 coliphage and 2009 Pandemic Influenza A (H1N1) Virus on FFR coupons in different matrices (viral media, 2% fetal bovine serum, and 5 mg ml^-1 mucin) were compared over time (4, 12, 24, 48, 72, and 144 hours) in typical absolute humidity conditions (4.1 × 10⁵ mPa [18°C/20% relative humidity (RH)]). Data revealed significant differences in viral infectivity over the 6-day period (H1N1- P <0.0001; MS2 - P <0.005), although a significant correlation of viral log₁₀ reduction in 2% FBS (P <0.01) was illustrated. Overall, MS2 coliphage was not determined to be a sufficient surrogate for influenza A virus with respect to droplet persistence when applied to the N95 FFR as a droplet.