Air-purifying Respirators Research Articles

Heat stress assessment during intermittent work under different environmental conditions and clothing combinations of effective wet bulb globe temperature (WBGT)

This study examined whether different combinations of ambient temperature and relative humidity for the effective wet bulb globe temperature, in conjunction with two different levels of clothing adjustment factors, elicit a similar level of heat strain consistent with the current threshold limit value guidelines. Twelve healthy, physically active men performed four 15-min sessions of cycling at a fixed rate of metabolic heat production of 350 watts. Each trial was separated by a 15-min recovery period under four conditions: (1) Cotton coveralls + dry condition (WD: 45.5 °C dry-bulb, 15% relative humidity); (2) Cotton coveralls + humid condition (WH: 31 °C dry-bulb, 84% relative humidity); (3) Protective clothing + dry condition (PD: 30 °C dry-bulb, 15% relative humidity); and (4) Protective clothing + humid condition (PH: 20 °C dry-bulb, 80% relative humidity). Gloves (mining or chemical) and headgear (helmet or powered air-purifying respirator) were removed during recovery with hydration ad libitum. Rectal temperature (Tre), skin temperature (Tsk), physiological heat strain (PSI), perceptual heat strain (PeSI), and body heat content were calculated. At the end of the 2-hr trials, Tre remained below 38 °C and the magnitude of Tre elevation was not greater than 1 °C in all conditions (WD: 0.9, WH: 0.8, WH: 0.7, and PD: 0.6 °C). However, Tsk was significantly increased by approximately 2.1 ± 0.8 °C across all conditions (all p ≤ 0.001). The increase in Tsk was the highest in WD followed by PD, WH, and PH conditions (all p ≤ 0.001). Although PSI and PeSI did not indicate severe heat strain during the 2-hr intermittent work period, PSI and PeSI were significantly increased over time (p ≤ 0.001). This study showed that core temperature and heat strain indices (PSI and PeSI) increased similarly across the four conditions. However, given that core temperature increased continuously during the work session, it is likely that the American Conference of Governmental Industrial Hygienist’s TLV® upper limit core temperature of 38.0 °C may be surpassed during extended work periods under all conditions.

Comparing Training Techniques in Chemical Disaster Preparedness

Introduction:Currently, there are no universally accepted personal protective equipment (PPE) training guidelines for Emergency Medicine physicians, though many hospitals offer training through a brief didactic presentation. Physicians’ response to hazmat events requires PPE utilization to ensure the safety of victims, facilities, and providers; providing effective and accessible training is crucial. In the event of a real disaster, time constraints may not allow a brief in-person presentation and an accessible video training may be the only resource available.Aim:To assess the effectiveness of video versus in-person training of 20 Emergency Medicine Residents in Level C PPE donning and doffing (chemical-resistant coverall, butyl gloves, boots, and an air-purifying respirator).Methods:A prospective observational study was performed with 20 Emergency Medicine residents as part of Emergency Preparedness training. Residents were divided into two groups, with Group A viewing a demonstration video developed by the emergency preparedness team, and Group B receiving in-person training by a Hazmat Team Member. Evaluators assessed critical tasks of donning and doffing PPE utilizing a prepared evaluation tool. At the drill’s conclusion, all participants completed a self-evaluation to determine their confidence in their respective trainings.Results:Both video and in-person training modalities showed significant improvement in participants’ confidence in doffing and donning a PPE suit (p>0.05). However, no statistically significant difference was seen between training modalities in the performance of donning or doffing (p>0.05).Discussion:Video and in-person training are equally effective in preparing residents for donning and doffing Level C PPE, with similar error rates in both modalities. Future trainings should focus on decreasing the overall rate of breaches across all training modalities.

User acceptance of reusable respirators in health care

BackgroundInclusion of reusable respirators, such as elastomeric half-face respirators (EHFRs) and powered air-purifying respirators (PAPRs), in hospital respiratory protection inventories may represent 1 solution to the problem of N95 respirator shortages experienced during pandemics. User acceptance of these devices is 1 potential barrier to implementing such a strategy in respiratory protection programs.MethodsTo assess user attitudes toward various respirators, health care workers enrolled in respiratory protection programs in a medical system using EHFRs, N95s, and PAPRs and completed an online questionnaire that addressed attitudes, beliefs, and respirator preferences under different risk scenarios. Responses were compared between user groups.ResultsOf 1,152 participants, 53% currently used N95s, 24% used EHFRs, and 23% used PAPRs. N95 users rated their respirators more favorably compared with EHFR and PAPR users (P < .001) regarding comfort and communication, however, EHFR users rated their respirators much more highly regarding sense of protection (P < .001). For all user groups, reusable respirators were significantly more likely (odds ratios 2.3-7.7) to be preferred over N95 filtering facepiece respirators in higher risk scenarios compared to “usual circumstance” scenarios.ConclusionsDespite somewhat less favorable ratings on comfort and communication, experienced EHFR and PAPR users still prefer reusable respirators over N95s in certain higher risk scenarios. This suggests that reusable respirators are an acceptable alternative to N95 respirators in health care and offer 1 viable solution to prevent pandemic-generated respirator shortages.

The impact of canister geometry on chemical biological radiological and nuclear filter performance: A computational fluid dynamics analysis

Steady-state axisymmetric simulations using the Reynolds-Averaged Navier-Stokes equations have been carried out in order to optimize the performance of a Chemical, Biological, Radiological, and Nuclear (CBRN) canister filter for its use in a powered air-purifying respirator (PAPR). Alterations have been made to the shape of the canister, the spacing of the rear wall of the canister with regard to the carbon filter, and the bracketing between (i) the particulate filter and the carbon bed and (ii) the carbon bed and the canister wall. The pressure drops across the canister and the residence time distribution at the rear of the carbon bed have been analyzed in detail based on an extensive parametric analysis involving the aforementioned variations. It has been demonstrated that the non-uniform porosity profile of the carbon bed resulted in alternating regions of high and low velocity close to the canister wall, providing a possible route for breakthrough. Designs, which included a bracket at the rear of the carbon bed, blocked this route and consequently had a longer minimum mean residence time than those, which did not. It has also been shown that the spacing between the carbon bed and the canister rear wall had a large impact on both residence time and pressure drop. In cases where the carbon backed directly onto the canister rear wall flow in the axial direction from the outside wall toward the canister axis resulted in far greater pressure drop and a reduction in minimum mean residence time within the carbon bed.

Evaluation of protection factor of respiratory protective equipment using indigenously developed protection factor test facility

Protection factor (PF) of a respirator is a number that describes the effectiveness of various classes of respirators in providing protection against exposure to airborne contaminants (including particulates, gases, vapors, and biological agents). The PF is derived from the ratio of the concentration of an airborne contaminant (e.g., hazardous substance) outside the respirator (Co) to the concentration inside the respirator (Ci) (i.e., Co/Ci). As the PF increases, there is an increase in the level of respiratory protection provided to employees by the respirator. PF Test Facility for the estimation of PF for various respiratory protective equipment was designed, fabricated, and installed at the Respiratory Protective Equipment Laboratory of Health Physics Division. The test facility consists of established air flow at a breathing rate through respirator darn on a human dummy and two identical tapings for iso-kinetic sampling from outside and inside the respirator. These tapings are coupled to two identical optical particle counters (OPCs) for the measurement of aerosol concentration simultaneously, and data acquired by the two OPCs are analyzed for estimating PF for different particle sizes using GRIM AEROSOL software. The results obtained from the studies carried out using this unique setup – air-purifying respirators such as half face mask, full face mask, and powered air-purifying respirators – were found offering a PF of 14, 112, and 1328, respectively, for selected range of 0.28–0.3-μm size standard sodium chloride (NaCl) aerosols. Standard NaCl aerosols used in experiments are polydispersed. However, the 0.3 μ size range (0.28–0.3) was selected as a benchmark for efficiency ratings and PF of respirators because it approximates the most difficult particle size for filters to capture and the least filtration efficiency is obtained in this range. This article brings out the details of design features of the setup and studies and results obtained for various types of respirators used in nuclear facilities.

Designing the half-masks of filter respirators for workers of mining enterprises

The purpose of paper is to develop an algorithm for designing the half-masks of air-purifying respirators and assessment of their safety factor of insulation. To create a 3D model of a head, two-parameter NIOSH tables (National Institute for Occupational Safety and Health) were used. The model drawings were made with the use of Solid works software package. Differential geometrical method based on applying the moving Frénet trihedral was used to design half-masks. Two designs of the respirator half-mask were developed based on the averaged length and width of face (Modification 1), and length of face and lips (Modification 2). As a result of modeling test, the area and perimeter of the mask contact line have been defined. The safety factor of half-mask insulation was calculated theoretically. It has been established that the safety factor of Modification 1 half-mask is 2.5 times higher.

Respirable Crystalline Silica Exposure among Concrete Finishing Workers at Apartment Complex Construction Sites

ABSTRACT The objective of this study was to evaluate the level of exposure to respirable crystalline silica (RCS) among concrete finishers and to identify the size distribution of particles from concrete finishing work at apartment complex construction sites. Active personal air sampling (n = 129) was conducted at eight sites using filters with aluminum cyclones, and local air sampling for the size distribution of the particles (n = 6) was conducted using a Mylar substrate with cascade impactors. Crystalline silica was analyzed by Fourier-transform infrared spectroscopy (FT-IR). The collected personal samples were sorted by the type of task (concrete chipping, grinding, or plastering) for four kinds of working places (exterior walls, interior walls of apartment units, staircases, and underground parking lots). The geometric mean (GM) of the RCS concentration was highest, although varying according to the type of structure, for concrete grinding (2.06 mg m–3), followed by chipping (0.12 mg m–3) and plastering (0.003 mg m–3). The maximum RCS concentration was measured in the staircases (4.18 mg m–3), followed by the interior walls of apartment units (2.76 mg m–3), underground parking lots (1.30 mg m–3), and exterior walls (0.89 mg m–3). The mass fraction of inhalable, thoracic, and respirable crystalline silica was respectively 73.9%, 40.2%, and 17.9% in chipping and 76.0%, 46.3%, and 19.7% in grinding. Concrete finishing workers at apartment complex construction sites are exposed to unacceptably high concentrations of RCS. To protect workers’ health, dust-minimizing construction methods as well as high-efficiency respirators paired with local exhaust ventilation systems or wet methods must be employed. Further efforts to reduce the total working time and to use full-faced air-purifying respirators are required.

Validation of Computational Fluid Dynamics Models for Evaluating Loose-Fitting Powered Air-Purifying Respirators.

Loose-fitting powered air-purifying respirators (PAPRs) are used in healthcare settings to reduce exposure to high-risk respiratory pathogens. Innovative computational fluid dynamics (CFD) models were developed for evaluating loose-fitting PAPR performance. However, the computational results of the CFD models have not been validated using actual experimental data. Experimental testing to evaluate particle facepiece leakage was performed in a test laboratory using two models of loose-fitting PAPRs. Each model was mounted on a static (non-moving) advanced headform placed in a sodium chloride (NaCl) aerosol test chamber. The headform performed cyclic breathing via connection to a breathing machine. High-efficiency particulate air (HEPA)-filtered air was supplied directly to the PAPR facepiece using laboratory compressed supplied-air regulated with a mass-flow controller. One model was evaluated with six supplied-air flowrates from 50-215 L/min (Lpm) and the other model with six flowrates from 50-205 Lpm. Three different workrates (minute volumes) were evaluated: low (25 Lpm), moderate 46 (Lpm), and high 88 (Lpm). Manikin penetration factor (mPF) was calculated as the ratio of chamber particle concentration to the in-facepiece concentration. Overall, data analyses indicated that the mPF results from the simulations were well correlated with the experimental laboratory data for all data combined (r = 0.88). For data at the three different workrates (high, moderate, low) for both models combined, the r-values were 0.96, 0.97, and 0.77, respectively. The CFD models of the two PAPR models were validated and may be utilized for further research.

A comparison of total inward leakage measured using sodium chloride (NaCl) and corn oil aerosol methods for air-purifying respirators

The International Organization for Standardization (ISO) standard 16900-1:2014 specifies the use of sodium chloride (NaCl) and corn oil aerosols, and sulfur hexafluoride gas for measuring total inward leakage (TIL). However, a comparison of TIL between different agents is lacking. The objective of this study was to measure and compare TIL for respirators using corn oil and NaCl aerosols. TIL was measured with 10 subjects donning two models of filtering facepiece respirators (FFRs) including FFP1, N95, P100, and elastomeric half-mask respirators (ERs) in NaCl and corn oil aerosol test chambers, using continuous sampling methods. After fit testing with a PortaCount (TSI, Inc., St. Paul, MN) using the Occupational Safety and Health Administration (OSHA) protocol, five subjects were tested in the NaCl chamber first and then in the corn oil chamber, while other subjects tested in the reverse order. TIL was measured as a ratio of mass-based aerosol concentrations in-mask to the test chamber, while the subjects performed ISO 16900-1-defined exercises. The concentration of NaCl aerosol was measured using two flame photometers, and corn oil aerosol was measured with one light scattering photometer. The same instruments were used to measure filter penetration in both chambers using a Plexiglas setup. The size distribution of aerosols was determined using a scanning mobility particle sizer and charge was measured with an electrometer. Filter efficiency was measured using an 8130 Automated Filter Tester (TSI). Results showed the geometric mean TIL for corn oil aerosol for one model each of all respirator categories, except P100, were significantly (p < 0.05) greater than for NaCl aerosol. Filter penetration in the two test chambers showed a trend similar to TIL. The count median diameter was ∼82 nm for NaCl and ∼200 nm for corn oil aerosols. The net positive charge for NaCl aerosol was relatively larger. Both fit factor and filter efficiency influence TIL measurement. Overall, TIL determination with aerosols of different size distributions and charges using different methodologies may produce dissimilar results.

Risk of self-contamination during doffing of personal protective equipment

The aim of this study was to describe the risk of self-contamination associated with doffing of personal protective equipment (PPE) and to compare self-contamination with various PPE protocols. We tested 10 different PPE donning and doffing protocols, recommended by various health organizations for Ebola. Ten participants were recruited for this study and randomly assigned to use 3 different PPE protocols. After donning of PPE, fluorescent lotion and spray were applied on the external surface of the PPE to simulate contamination, and ultraviolet light was used to count fluorescent patches on the skin. After testing 30 PPE sequences, large fluorescent patches were recorded after using "WHO coverall and 95" and "North Carolina coverall and N95" sequences, and small patches were recorded after using "CDC coverall and N95" and "Health Canada gown and N95" sequences. Commonly reported problems with PPE use were breathing difficulty, suffocation, heat stress, and fogging-up glasses. Most participants rated PPE high (18/30) or medium (11/30) for ease of donning/doffing and comfort. PPE sequences with powered air-purifying respirators (PAPRs) and assisted doffing were generally associated with fewer problems and were rated the highest. This study confirmed the risk of self-contamination associated with the doffing of PPE. PAPR-containing protocols and assisted doffing should be preferred whenever possible during the outbreak of highly infectious pathogens.

Respiratory Protection Provided by Negative Pressure Half Mask Filtering Respirators in Coal Mines

Two studies were conducted in the coal mines to evaluate worker exposures to a dust, and the effectiveness of air-purifying negative-pressure half mask respirators and was found that miners’ protection were insufficient. An elastomeric and filtering half-mask negative pressure respirators with (mid-efficiency) filters P2 (FFP2) were studied. Measurements of total dust concentrations in the in-mask and outer air were conducted simultaneously. Not identical sampling system led to an underestimation of the actual total inside dust concentration in the first study. The results have been corrected to reduce the systematic error. The inside total dust concentrations Ci exceeded national Permissible Exposure Limit (PEL) in most cases in both studies; in first GM Ci=24.7 mg/m3; in second 8.6 mg/m3. Protection factors were: from 2.9 to 6.9 in first study; and from 5.6 to 34 in second. Low efficiency of respirators can be caused by its non-continuous usage. High risk of miners’ occupational diseases should be reduced by decreasing the dust concentration in the breathing zone. It is advisable to check the possibility of improving respiratory protection of miners by powered air-purifying respirators.

Could portable powered respirators help us avoid the exposure to air pollution?

Atmospheric pollution has become a persistent threat to human health. Consequently, the effects of breathing polluted air in large cities are being assessed for given risk groups and different indoor and outdoor activities. This work delves into the study of the possibility to develop individual portable air-purifying respirators to avoid the exposure to atmospheric pollution when carrying out common daily activities at home or outdoors. Samples of known concentrations of the criteria pollutants (except for lead) have been monitored before and after passing through a powered occupational respirator which has been also tested carrying out physical activities mainly under outdoor conditions. The results show that the system is not effective against carbon monoxide but it does provide protection against particulate matter, SO2, NOx, O3, and volatile organic compounds, that is, most of the main pollutants found in outdoor air. Thus, individual powered respirators are technologically viable based on the current occupational devices and by providing them with additional suggested improvements. Being affordable, this kind of systems may become very helpful not only for assistive applications but also for healthy people willing to reduce exposure to air pollution.

Perceived Exertion Responses While Wearing Tight- and Loose-Fitting Powered Air-Purifying Respirators

Perceived Exertion Responses While Wearing Tight- and Loose-Fitting Powered Air-Purifying Respirators

Workplace Respiratory Protection Factors during Asbestos Removal Operations.

Numerous changes have been made to the French labour regulations in recent years relating to the prevention of risks of exposure to asbestos fibres for operators removing asbestos-containing materials. These changes refer to the method used to count fibres, the collective and personal protective devices to be used on these worksites, and the occupational exposure limit value, which was reduced to 10 f.L-1 on 2 July 2015. In this context, this study assessed the level of respiratory protection afforded by supplied-air respirators and powered air-purifying respirators by monitoring exposure for several operators on nine worksites. The levels of dustiness measured in personal samples taken outside masks showed significant evidence of potential exposure during removal of asbestos-containing plaster or sprayed asbestos, and when using abrasive blasting to treat asbestos-containing materials. For these tasks outside concentration regularly exceeds 25000 f.L-1. Measurements inside masks were generally low, under 10 f.L-1, except in some situations involving the removal of asbestos-containing plaster. This partial penetration of fibres inside masks could be due to the high loading linked to this material. The distributions of Workplace Protection Factors obtained for the two types of respiratory protective devices studied were broad, and the fifth percentile values equal to 236 and 104, respectively, for supplied-air respirators and powered air-purifying respirators. This work highlights once again the need to prioritize collective protection when seeking to prevent asbestos-related risks.

Disclosure and Fit Capability of the Filtering Facepiece Respirator.

The filtering facepiece air-purifying respirator is annually purchased in the tens of millions and widely used for worker protection from harmful airborne particulates. The workplace consumers of this safety product, i.e., employers, workers, and safety and health professionals, have assurances of its effectiveness through the respirator certification and disclosure requirements of the National Institute for Occupational Safety and Health. However, the certification of a critical performance requirement has been missing for the approved filtering facepiece respirator since 1995: fit capability. Without this certification, consumers continue to be at risk of purchasing a respirator model that may fit a small percentage of the intended users. This commentary updates and expands an earlier one by this author, addresses the consequences of poorly fitting certified models on the market and lack of disclosure, and calls for further action by National Institute for Occupational Safety and Health to meet the needs and expectations of the consumer.

Assessment of half-mask elastomeric respirator and powered air-purifying respirator reprocessing for an influenza pandemic

Health care facilities are considering the use of reusable respiratory protective devices (RPDs) to mitigate a potential N95 filtering facepiece respirator shortage caused by an influenza pandemic. US regulators are also considering stockpiling reusable RPDs for pandemic preparedness, but limited data exist on the effectiveness of cleaning and disinfection of these devices. This study defines reprocessing protocols and evaluates their effectiveness against a pandemic influenza strain in a laboratory setting. Five half-mask elastomeric respirator models and 3 powered air-purifying respirator models were contaminated with influenza virus and artificial skin oil on multiple surfaces. RPDs were then manually treated with 1 of 2 methods: cleaned or cleaned and disinfected. Presence of viable influenza was determined via swab sampling and a median tissue culture infectious dose assay. Across 41 RPD surfaces, a mean log reduction in viable influenza of 4.54 ± 0.97 log10 median tissue culture infectious dose was achieved for all treated surfaces, which included both cleaned and cleaned and disinfected surfaces. The methods defined as part of this study are effective for eliminating viable influenza in the presence of artificial skin oil on most of the RPD surfaces tested. Material type and RPD design should be considered when implementing RPD reprocessing protocols.

Powered air-purifying respirator use in healthcare: Effects on thermal sensations and comfort

ABSTRACTTwelve subjects wore an N95 filtering facepiece respirator (N95 FFR), one tight-fitting full facepiece powered air-purifying respirator (PAPR), two loose-fitting PAPRs, and one elastomeric/PAPR hybrid for 1 hr each during treadmill walking at 5.6 km/hr while undergoing physiological and subjective response monitoring. No significant interaction (p ≥ .05) was noted between the five respirators in heart rate, respiratory rate, oxygen saturation, transcutaneous carbon dioxide, and perceptions of breathing effort or discomfort, exertion, facial heat, and overall body heat. Respirator deadspace heat/humidity were significantly greater for the N95 FFR, whereas tympanic forehead skin temperatures were significantly greater for the hybrid PAPR. Temperature of the facial skin covered by the respirator was equivalent for the N95 FFR and hybrid PAPR, and both were significantly higher than for the other three PAPRs. Perception of eye dryness was significantly greater for a tight-fitting full facepiece PAPR than the N95 FFR and hybrid PAPR. At a low-moderate work rate over 1 hr, effects on cardiopulmonary variables, breathing perceptions, and facial and overall body heat perceptions did not differ significantly between the four PAPRs and a N95 FFR, but the tight-fitting, full facepiece PAPR increased perceptions of eye dryness. The two loose-fitting PAPRs and the full facepiece tight-fitting PAPR ameliorated exercise-induced increases in facial temperature, but this did not translate to improved perception of facial heat and overall body heat.

Recommended test methods and pass/fail criteria for a respirator fit capability test of half-mask air-purifying respirators

ABSTRACTThis study assessed key test parameters and pass/fail criteria options for developing a respirator fit capability (RFC) test for half-mask air-purifying particulate respirators. Using a 25-subject test panel, benchmark RFC data were collected for 101 National Institute for Occupational Safety and Health-certified respirator models. These models were further grouped into 61 one-, two-, or three-size families. Fit testing was done using a PortaCount® Plus with N95-Companion accessory and an Occupational Safety and Health Administration-accepted quantitative fit test protocol. Three repeated tests (donnings) per subject/respirator model combination were performed. The panel passing rate (PPR) (number or percentage of the 25-subject panel achieving acceptable fit) was determined for each model using five different alternative criteria for determining acceptable fit.When the 101 models are evaluated individually (i.e., not grouped by families), the percentages of models capable of fitting >75% (19/25 subjects) of the panel were 29% and 32% for subjects achieving a fit factor ≥100 for at least one of the first two donnings and at least one of three donnings, respectively. When the models are evaluated grouped into families and using >75% of panel subjects achieving a fit factor ≥100 for at least one of two donnings as the PPR pass/fail criterion, 48% of all models can pass. When >50% (13/25 subjects) of panel subjects was the PPR criterion, the percentage of passing models increased to 70%.Testing respirators grouped into families and evaluating the first two donnings for each of two respirator sizes provided the best balance between meeting end user expectations and creating a performance bar for manufacturers. Specifying the test criterion for a subject obtaining acceptable fit as achieving a fit factor ≥100 on at least one out of the two donnings is reasonable because a majority of existing respirator families can achieve an PPR of >50% using this criterion. The different test criteria can be considered by standards development organizations when developing standards.

Aerosol Generation During Bone-Sawing Procedures in Veterinary Autopsies.

Bone-sawing procedures are routinely performed during veterinary and human autopsies and represent an important source for infectious aerosols. Here we investigate the generation of aerosols during bone-sawing procedures using 5 different saws regularly used in veterinary and human pathology. In particular, the electrical bone band saw produced vast amounts of aerosolized particles less than 5 µm in diameter, which spread rapidly throughout the entire autopsy hall, leading to an exposure of all personnel. Other sawing devices tested were a diamond-coated cut grinder, an oscillating saw, a reciprocating saw, and a hand bone saw. Although these saws, especially the handsaw, generated fewer aerosolized particles than the band saw, the level of exposure of the saw operator would still be of concern in cases where infectious material would require sawing. Contamination of the entire autopsy area was successfully prevented by the construction of a separately ventilated sawing cabin inside the existing autopsy room. Saw operators in this cabin, however, were exposed to even higher aerosol concentrations. Protection of saw operators was achieved by using a powered air-purifying respirator. In conclusion, our results demonstrate that all bone-sawing procedures applied in veterinary and human pathology can generate aerosols that are of concern for the health of autopsy personnel. To reduce the risk of aerosol infections from bone-sawing procedures, efficient and properly designed ventilation systems to limit the spread of aerosols and appropriate personal protective equipment against aerosols for exposed personnel should be implemented.

Evaluation of a Novel Powered Air-purifying respirator (PAPR) vs. a N95 Respirator Mask for the Protection Against Influenza in a Human Exposure Model

Evaluation of a Novel Powered Air-purifying respirator (PAPR) vs. a N95 Respirator Mask for the Protection Against Influenza in a Human Exposure Model