Workplace Protection Factor Research Articles

Personal protective equipment for preventing asbestos exposure in workers.

Personal protective equipment for preventing asbestos exposure in workers.

Simulated workplace protection factor study of a quarter-facepiece elastomeric respirator

The assigned protection factor (APF) for quarter-facepiece respirators is currently 5, based on fit test data from the 1970s with models no longer commercially available. The goal of this project was to evaluate the respirator fit capability of a NIOSH-approved N95 quarter-facepiece elastomeric respirator with a gel-based facial seal design (Envo Mask by Sleepnet Corporation). Human subjects were recruited from healthcare and the general population to satisfy a 25-member NIOSH bivariate panel. Subjects were fit tested with a fast fit protocol using a TSI Portacount Model 8038 in the N95 mode. Second-by-second measures of fit were then collected while subjects performed a 30-min series of simulated healthcare activities. Subjects completed a short comfort questionnaire. The median (5th, 95th percentile) fit factor was 188 (48, 201). Simulated workplace protection factors (SWPFs) had a median (5th, 95th percentile) of 181 (94, 199) (data truncated at 200) and 570 (153, 1508) (non-truncated data). Subjects ranked inhalation and exhalation as “easy” with average scores of 5.0/6.0 and 5.2/6.0, respectively. The facepiece was ranked between slightly comfortable and comfortable (4.8/6.0) and the harness as comfortable (5.0/6.0). Most users agreed (5.2/6.0) that the mask was stable on their faces. The 5th percentile SWPF of 95 supports an APF of at least 10 for this quarter-facepiece elastomeric respirator, similar to the APF for half-facepiece respirators. This study supports increasing the APF for quarter-facepiece respirators, a class that has been largely ignored by manufacturers for the past 40 years. A lightweight, low profile, reusable quarter-facepiece respirator is an effective option for healthcare and other worker protection during a pandemic and similar situations.

HALO CleanSpace PAPR evaluation: Communication, respiratory protection, and usability.

To evaluate a relatively new half-face-piece powered air-purifying respirator (PAPR) device called the HALO (CleanSpace). We assessed its communication performance, its degree of respiratory protection, and its usability and comfort level. This simulation study was conducted at the simulation center of the Royal Melbourne Hospital. In total, 8 voluntary healthcare workers participated in the study: 4 women and 4 men comprising 3 nursing staff and 5 medical staff. We performed the modified rhyme test, outlined by the National Institute for Occupational Safety and Health (NIOSH), for the communication assessment. We conducted quantitative fit test and simulated workplace protection factor studies to assess the degree of respiratory protection for participants at rest, during, and immediately after performing chest compression. We also invited the participants to complete a usability and comfort survey. The HALO PAPR met the NIOSH minimum standard for speech intelligibility, which was significantly improved with the addition of wireless communication headsets. The HALO provided consistent and adequate level of respiratory protection at rest, during and after chest compression regardless of the device power mode. It was rated favorably for its usability and comfort. However, participants criticized doffing difficulty and perceived communication interference. The HALO device can be considered as an alternative to a filtering face-piece respirator. Thorough doffing training and mitigation planning to improve the device communication performance are recommended. Further research is required to examine its clinical outcomes and barriers that may potentially affect patient or healthcare worker safety.

Measurement of the Workplace Protection Factor of Replaceable Particulate and Powered Air-purifying Respirators in Japanese Dust-generating Occupations

Although measuring the workplace protection factor (WPF) is important to verify the performance of particulate respirators in a real work environment, there are no reports of such measurements in Japan. The aim of this study was to measure the WPF of a replaceable particulate respirator (RPR) and a powered air-purifying respirator (PAPR). Eight participants were subjected to three conditions: wearing a RPR correctly (C-RPR), wearing a RPR as usual (but incorrectly) (U-RPR), and wearing a PAPR in the same way as U-RPR (PAPR). Subjects performed dust-generating tasks for 15 min, during which the WPF was measured. The WPF was calculated by dividing the concentration of particles outside the particulate respirator (Co) by that inside the particulate respirator (Ci). A fit testing instrument was used to measure the number of particles. Ci was measured by inserting the test guide into the face piece, and Co was measured by fixing the test guide near the breathing area of the subjects. The WPF geometric mean values (standard deviations) for C-RPR, U-RPR, and PAPR were 17.7 (2.59), 27.0 (3.86), and 117.3 (5.25), respectively. It is important to generate knowledge about the performance of particulate respirators to prevent occupational respiratory diseases.

The protective effect of tight-fitting powered air-purifying respirators during chest compressions.

Airborne personal protective equipment is required for healthcare workers when performing aerosol-generating procedures on patients with infectious diseases. Chest compressions, one of the main components of cardiopulmonary resuscitation, require intense and dynamic movements of the upper body. We aimed to investigate the protective effect of tight-fitting powered air-purifying respirators (PAPRs) during chest compressions. This single-center simulation study was performed from February 2021 to March 2021. The simulated workplace protection factor (SWPF) is the concentration ratio of ambient particles and particles inside the PAPR mask; this value indicates the level of protection provided by a respirator when subjected to a simulated work environment. Participants performed continuous chest compressions three times for 2 min each time, with a 4-min break between each session. We measured the SWPF of the tight-fitting PAPR during chest compression in real-time mode. The primary outcome was the ratio of any failure of protection (SWPF <500) during the chest compression sessions. Fifty-four participants completed the simulation. Overall, 78% (n = 42) of the participants failed (the measured SWPF value was less than 500) at least one of the three sessions of chest compressions. The median value and interquartile range of the SWPF was 4304 (685-16,191). There were no reports of slipping down of the respirator or mechanical failure during chest compressions. Although the median SWPF value was high during chest compressions, the tight-fitting PAPR did not provide adequate protection.

Investigating the field effectiveness of respirators against metal particle exposure in various workplaces: a systematic review.

Welders are exposed to high levels of metal fumes, which could be resulting in various health impairments. Respirators became a practical protective option in workplaces, as they are lightweight and easy to use. This systematic review attempts to explore the field effectiveness of using respirators to reduce metal particle exposure in workplaces. We reviewed papers published from 1900 to April 2019 in five major bibliographic databases, including Embase, Web of Science, Medline, Scopus, and CINAHL, along with organizational websites to cover gray literature. In total, 983 references were identified from the databases, out of which, 520 duplicates were removed from the EndNote database. The remaining 463 references were screened for their title and abstract. Out of 463, 70 references went through the full-text screening. Finally, eight papers, including 19 workplace respirator studies, satisfied all the inclusion criteria and were reviewed in this report. The geometric means for metal levels in workers' breathing zone with and without respirators were 9.4 and 1,777µg/m3 for iron, 1.1 and 139µg/m3 for lead, 2.1 and 242µg/m3 for zinc, and 27 and 1,398µg/m3 for manganese oxide, respectively. Most reviewed studies reported significant differences between measured metal particle levels among workers who worn respirators and who did not. In addition, results showed that N95 provided significantly less protection thanelastomeric half facepieces, full-face respirators, and powered air-purifying respirators (p<0.001). More field studies are recommended to investigate Workplace Protection Factor (WPF) and fit factor (FF) of different respirators to understand the actual protection levels that they could be provided to control welding fume exposure among welders in various workplaces.

Comparing respirator laboratory protection factors measured with novel personal instruments to those from the PortaCount

A quantitative fit test is performed using a benchtop instrument (e.g., TSI PortaCount) to assess the fit factor provided by a respirator when assigned to a worker. There are no wearable instruments on the market to measure protection factors while the respirator is in use. The aim of this study is to evaluate two new, wearable, quantitative instruments—a dual-channel optical particle counter (DC OPC) and a dual-channel condensation particle counter (DC CPC)—that would enable in-situ, real-time measurement of respirator workplace protection factor. Respirator laboratory protection factors measured by the new instruments were compared to those measured with the TSI PortaCount on one test subject for three test aerosols (sodium chloride, incense, ambient) at target laboratory protection factors of 100, 300, and 1,000 for sodium chloride and ambient, and 75 and 500 for incense. Three replicates were performed for each test condition. Data were analyzed with a two-sided paired t-test at a significance level of 0.05. Laboratory protection factors measured with the DC CPC agree with those measured with the PortaCount whereas those from the DC OPC generally do not. Mean laboratory protection factors derived from the DC CPC are only statistically significantly different for mean values of a laboratory protection factor at ambient conditions for a target laboratory protection factor of 300 (p = 0.02) and for incense at a target laboratory protection factor of 75 (p = 0.03). Although statistically significant, the difference in laboratory protection factors derived from the DC CPC are not substantial in practice and may be explained by systematic uncertainty. In contrast, the DC OPC reports substantially larger mean laboratory protection factors, differing by about half an order of magnitude in extreme cases, and statistically significantly different mean laboratory protection factors for the sodium chloride aerosol for target laboratory protection factors of 100 and 300 (p = 0.01 and p = 0.01).

The impact of extreme reuse and extended wear conditions on protection provided by a surgical-style N95 filtering facepiece respirator

Most respirators employed in health care settings, and often in first responder and industrial settings, are intended for single-use: the user dons the respirator, performs a work activity, and then doffs and discards the respirator. However, in the current COVID-19 pandemic, in the presence of persistent shortages of personal protective equipment, extended use and reuse of filtering facepiece respirators are routinely contemplated by many health care organizations. Further, there is considerable current effort to understand the effect of sterilization on the possibility of reuse, and some investigations of performance have been conducted. While the ability of such a respirator to continue to provide effective protection after repeated sanitization cycles is a critical component of implementing its reuse, of equal importance is an understanding of the impact that reusing the respirator multiple times in a day while performing work tasks, and even extending its wear over multiple days, has on the workplace protective performance. In this study, we subjected a stockpiled quantitatively fitted surgical style N95 filtering facepiece respirator device to extreme reuse and extended wear conditions (up to 19 uses over a duration of 5 days) and measured its protective performance at regular intervals, including simulated workplace protection factor measurements using total inward leakage. With this respirator, it was shown to be possible to maintain protection corresponding to an assigned protection factor greater than 10 under extreme usage conditions provided an individual is properly trained in the use of, and expertly fitted in, the respirator. Other factors such as hygiene and strap breakage are likely to place limits on reuse.

New respirator performance monitor (RePM) for powered air-purifying respirators

Powered air-purifying respirators (PAPRs) that offer protection from particulates are deployed in different workplace environments. Usage of PAPRs by healthcare workers is rapidly increasing; these respirators are often considered the best option in healthcare settings, particularly during public health emergency situations, such as outbreaks of pandemic diseases. At the same time, lack of user training and certain vigorous work activities may lead to a decrease in a respirator’s performance. There is a critical need for real-time performance monitoring of respiratory protective devices, including PAPRs. In this effort, a new robust and low-cost real-time performance monitor (RePM) capable of evaluating the protection offered by a PAPR against aerosol particles at a workplace was developed. The new device was evaluated on a manikin and on human subjects against a pair of condensation nuclei counters (P-Trak) used as the reference protection measurement system. The outcome was expressed as a manikin-based protection factor (mPF) and a Simulated Workplace Protection Factor (SWPF) determined while testing on subjects. For the manikin-based testing, the data points collected by the two methods were plotted against each other; a near-perfect correlation was observed with a correlation coefficient of 0.997. This high correlation is particularly remarkable since RePM and condensation particle counter (CPC) measure in different particle size ranges. The data variability increased with increasing mPF. The evaluation on human subjects demonstrated that RePM prototype provided an excellent Sensitivity (96.3% measured on human subjects at a response time of 60 sec) and a Specificity of 100%. The device is believed to be the first of its kind to quantitatively monitor PAPR performance while the wearer is working; it is small, lightweight, and does not interfere with job functions.

A technique to measure respirator protection factors against aerosol particles in simulated workplace settings using portable instruments

The aim of this study was to develop a new method to measure respirator protection factors for aerosol particles using portable instruments while workers conduct their normal work. The portable instruments, including a set of two handheld condensation particle counters (CPCs) and two portable aerosol mobility spectrometers (PAMSs), were evaluated with a set of two reference scanning mobility particle sizers (SMPSs). The portable instruments were mounted to a tactical load-bearing vest or backpack and worn by the test subject while conducting their simulated workplace activities. Simulated workplace protection factors (SWPFs) were measured using human subjects exposed to sodium chloride aerosols at three different steady state concentration levels: low (8x103 particles/cm3), medium (5x104 particles/cm3), and high (1x105 particles/cm3). Eight subjects were required to pass a quantitative fit test before beginning a SWPF test for the respirators. Each SWPF test was performed using a protocol of five exercises for 3 min each: (1) normal breathing while standing; (2) bending at the waist; (3) a simulated laboratory-vessel cleaning motion; (4) slow walking in place; and (5) deep breathing. Two instrument sets (one portable instrument {CPC or PAMS} and one reference SMPS for each set) were used to simultaneously measure the aerosol concentrations outside and inside the respirator. The SWPF was calculated as a ratio of the outside and inside particles. Generally, the overall SWPFs measured with the handheld CPCs had a relatively good agreement with those measured with the reference SMPSs, followed by the PAMSs. Under simulated workplace activities, all handheld CPCs, PAMSs, and the reference SMPSs showed a similar GM SWPF trend, and their GM SWPFs decreased when simulated workplace movements increased. This study demonstrated that the new design of mounting two handheld CPCs in the tactical load-bearing vest or mounting one PAMS unit in the backpack permitted subjects to wear it while performing the simulated workplace activities. The CPC shows potential for measuring SWPFs based on its light weight and lack of major instrument malfunctions.

Evaluation of a New Workplace Protection Factor-Measuring Method for Filtering Facepiece Respirator.

BackgroundThis study aims to assess whether the TSI PortaCount (Model 8020) is a measuring instrument comparable with the flame photometer. This would provide an indication for the suitability of the PortaCount for determining the workplace protection factor for particulate filtering facepiece respirators.MethodsThe PortaCount (with and without the N95-Companion™) was compared with a stationary flame photometer from Moores (Wallisdown) Ltd (Type 1100), which is a measuring instrument used in the procedure for determining the total inward leakage of the particulate filtering facepiece respirator in the European Standard. Penetration levels of sodium chloride aerosol through sample respirators of two brands (A and B) were determined by the two measuring systems under laboratory conditions. For each brand, thirty-six measurements were conducted. The samples were split into groups according to their protection level, conditioning before testing, and aerosol concentration. The relationship between the gauged data from two measuring systems was determined. In addition, the particle size distribution inside the respirator and outside the respirator was documented. Linear regression analysis was used to calculate the association between the PortaCount (with and without the N95-Companion™) and the flame photometer.ResultsA linear relationship was found between the raw data scaled with the PortaCount (without N95-Companion™) and the data detected by the flame photometer (R2 = 0.9704) under all test conditions. The distribution of particle size was found to be the same inside and outside the respirator in almost all cases.ConclusionBased on the obtained data, the PortaCount may be applicable for the determination of workplace protection factor.

THE SELECTION OF THE RESPIRATORS AS A RESULT OF STUDIES OF THEIR WORKPLACE PROTECTION FACTORS (REVIEW)

Currently, respiratory protective devices (RPD) play an important role in the system of the workers’ protection from the polluted atmosphere in the Russian Federation. The article describes the history of evaluation of workplace protection factors (WPFs) in USA and UK, and their impact on the law requirements for the employers (in developed countries), that determine the selection of RPD for known workplaces’ conditions. WPFs measurements revealed a low efficiency of the four types of RPD compared to measurements in laboratories. This difference prompted a change in the requirements for employers. The Assigned Protection Factors of three types of Powered Air Purifying Respirators (PAPRs) were reduced: for PAPRs with a full facepiece - from 2000 to 40; for PAPRs with hood or helmet - from 1000 to 25; for PAPRs with half mask - from 500 to 50. The Assigned Protection Factor of gas masks was reduced from 900 to 40. Western requirements for selecting RPD are compared with the practice and recommendations for choosing RPD in the RF. There were revealed significant differences increasing the risk of acute poisoning and the development of chronic diseases among workers. Specific recommendations are given to reduce these risks: reduction of air pollution in the workplaces; development of requirements for the selection of RPD in the RF, based on the best Western requirements; participation of the industrial hygienists in the development of requirements for RPD and training materials for the specialists and workers; development and implementation of the Biological Exposure Indices.

Real-time performance of filtering facepiece respirators at the workplace/Echtzeit-Performance partikelfiltrierender Halbmasken am Arbeitsplatz

The efficacy of a respirator under real workplace conditions is presented by its workplace protection factor (WPF). The aim of this study was to assess a portable measuring system for the determination of WPF for particulate filtering facepiece respirators. WPFs of CE-marked FFP2 and FFP3 filtering facepiece respirators were measured as a pilot test conducted at two workplaces: an inter-company training facility and a paper mill, with a total of seven test subjects. Each subject was quantitatively fit tested prior to the field measurements. Two TSI PortaCount instruments measured the particle concentrations simultaneously and continuously inside and outside the respirator for 15 min, with three repetitions. The results of the fit test (overall fit factor) ranged from 22 to 199. Individual WPF results ranged from 16 to 568 for FFP2 respirators, and from 13 to 232 for FFP3 respirators. The geometric means (GM) of the WPF were 135 with a 5th percentile value of 37 (FFP2), and 47 with a 5th percentile value of 12 (FFP3). This pilot test provides a new method of evaluating the workplace performance of filtering facepiece 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.

Size-selective Assessment of Respirator Protection against Airborne Fungi and (1→3)-β-D-glucan in Farms

(1→3)-β-D-glucan is a major component of the fungal cell wall. It is commonly used to evaluate human exposure to fungi. A personal sampling system was developed to size-selectively evaluate the workplace protection factors (WPFs) of N95 filtering facepiece respirators (FFRs) and surgical masks (SMs) against fungi. This field study was performed with human subjects wearing an N95 FFR or a SM during farming activities. The geometric means of the WPFs of N95 FFRs and SMs were 156.2 and 12.2 for the total culturable fungi, 55.4 and 9.0 for the total fungi, and 10.5 and 11.1 for (1→3)-β-D-glucan. The WPFs for N95 FFRs against fungal contaminants were mostly greater than those for SMs; however, about 4.8%–35.0% of WPFs in the spore size range > 1.8 µm were still below 10 (the assigned protection factor designated for N95 FFRs by the US Occupational Safety and Health Administration). The WPFs of N95 FFRs and SMs against culturable fungi and (1→3)-β-D-glucan increased with the particle size. The total (1→3)-β-D-glucan significantly correlated with the total fungi (r = 0.588, p < 0.001) and total culturable fungi (r = 0.463, p = 0.002), which suggests that (1→3)-β-D-glucan can be used as an indicator to assess respiratory protection against airborne fungi on agricultural farms.

Simulated workplace protection factors for respirators with N95 or higher filters for health care providers in an emergency medical centre: A randomized crossover study

Introduction:Health care providers in emergency medical centres often encounter infected sources during medical procedures; these sources can generate droplets. Wearing respirators could help to protect against infection risk. However, to the best of our knowledge, no previous study has reported the efficacy of N95 or higher respirators for health care providers in emergency medical centres.Methods:A randomized, crossover study of 26 health care providers was conducted to examine the protective performance of respirators. Quantitative fit tests with three types of respirators (cup type, fold type without valve and fold type with valve) were performed using seven exercises. Primary outcomes were the fit factors. Secondary outcomes included the percentage of fit factors above 100 and respirator preference.Results:After excluding one participant, data for 25 participants were analysed. The fit factors and the percentage of fit factors above 100 were higher when participants wore a fold-type respirator (200 fit factors [38.6–200], 100% [0–100]) relative to those for the cup-type respirator (114.0 fit factors [16.0–185.2], 60% [0–100]) and valve-type respirator (84.9 fit factors [14.2–170.8], 23.8 % [0–100]) in normal respiration. There was no clear preference regarding the type of respirator.Conclusion:The type of respirator could influence protective performance for health care providers. Health care providers in emergency medical centres should be aware of and wear the type of respirator that is well-fitted for them in advance.

Surgical Smoke Simulation Study: Physical Characterization and Respiratory Protection.

Exposure of operating room (OR) personnel to surgical smoke, a unique aerosol generated from the common use of electrocautery during surgical procedures, is an increasing health risk concern. The main objective of this simulation study was to characterize the surgical smoke exposure in terms of the particle number concentration and size distribution in a human breathing zone. Additionally, the performance of respiratory protective devices designed for ORs was examined using two commercially available N95 facepiece filtering respirators (FFRs) as well as the same FFRs modified with new faceseal technology. The tests were conducted in an OR-simulating exposure chamber with the surgical smoke generated by electrocautery equipment applied to animal tissue and measured in the breathing zone with four aerosol spectrometers. The simulated workplace protection factor of each tested respirator was determined for ten subjects by measuring the total aerosol concentrations inside and outside of a respirator. The peak of the particle size distribution was in a range of 60-150 nm. The concentration of particles generated during the simulated surgical procedure significantly exceeded the background concentration under all tested air exchange conditions. The data suggest that wearing N95 filtering facepiece respirators significantly decreased the human exposure to surgical smoke. The new faceseal technology provided significantly higher respiratory protection than the commercial N95 FFRs.

Numerical studies on the performance of an aerosol respirator with faceseal leakage

We studied the efficiency of a facepiece filtering respirator (FFR) in presence of a measurable faceseal leakage using the previously developed model of a spherical sampler with porous layer. In our earlier study, the model was validated for a specific filter permeability value. In this follow-up study, we investigated the effect of permeability on the overall respirator performance accounting for the faceseal leakage. The Total Inward Leakage (TIL) was calculated as a function of the leakage-to-filter surface ratio and the particle diameter. A good correlation was found between the theoretical and experimental TIL values. The TIL value was shown to increase and the effect of particle size on TIL to decrease as the leakage-to- filter surface ratio grows. The model confirmed that within the most penetrating particle size range (∼50 nm) and at relatively low leakage-to-filter surface ratios, an FFR performs better (TIL is lower) when the filter has a lower permeability which should be anticipated as long as the flow through the filter represents the dominant particle penetration pathway. An increase in leak size causes the TIL to rise; furthermore, under certain leakage-to-filter surface ratios, TIL for ultrafine particles becomes essentially independent on the filter properties due to a greater contribution of the aerosol flow through the faceseal leakage. In contrast to the ultrafine fraction, the larger particles (e.g., 800 nm) entering a typical high- or medium-quality respirator filter are almost fully collected by the filter medium regardless of its permeability; at the same time, the fraction penetrated through the leakage appears to be permeability- dependent: higher permeability generally results in a lower pressure drop through the filter which increases the air flow through the filter at the expense of the leakage flow. The latter reduces the leakage effect thus improving the overall respiratory protection level. The findings of this study provide valuable information for developing new respirators with a predictable actual workplace protection factor.

Performance of Facepiece Respirators and Surgical Masks Against Surgical Smoke: Simulated Workplace Protection Factor Study.

Objective:Surgical smoke generated during electrocautery contains toxins which may cause adverse health effects to operating room (OR) personnel. The objective of this study was to investigate the performance of surgical masks (SMs), which are routinely used in ORs, more efficient N95 surgical mask respirator (SMRs) and N100 filtering facepiece respirator (FFRs), against surgical smoke.Methods:Ten subjects were recruited to perform surgical dissections on animal tissue in a simulated OR chamber, using a standard electrocautery device, generating surgical smoke. Six respiratory protective devices (RPDs) were tested: two SMs, two SMRs, and two N100 FFRs [including a newly developed faceseal (FS) prototype]. Fit testing was conducted before the experiment. Each subject was then exposed to the surgical smoke while wearing an RPD under the tests. Concentrations inside (Cin) and outside (Cout) of the RPD were measured by a particle size spectrometer. The simulated workplace protection factor (SWPF) was determined by the ratio of Cout and Cin for each RPD-wearing subject.Results:For the SMs, the geometric means of SWPFtotal (based on the total aerosol concentration) were 1.49 and 1.76, indicating minimal protection. The SWPFtotal values of the SMRs and N100 FFRs were significantly higher than those of the SMs: for the two SMRs, the SWPFtotal were 208 and 263; for the two N100s, the SWPFtotal values were 1,089 and 2,199. No significant difference was observed between either the two SMs or the two SMRs. The SWPFtotal for the novel FS prototype N100 FFR was significantly higher than the conventional N100 FFR. The correlation between SWPFtotal and fit factor (FF) determined for two N95 SMRs was not significant.Conclusions:SMs do not provide measurable protection against surgical smoke. SMRs offer considerably improved protection versus SMs, while the N100 FFRs showed significant improvement over the SMRs. The FS prototype offered a higher level of protection than the standard N100 FFR, due to a tighter seal. While we acknowledge that conventional N100 FFRs (equipped with exhalation valves) are not practical for human OR use, the results obtained with the FS prototype demonstrate the potential of the new FS technology for implementation on various types of respirators.

Comparison of Simulated Workplace Protection Factors Offered by N95 and P100 Filtering Facepiece and Elastomeric Half-Mask Respirators against Particles of 10 to 400 nm.

This study compared the simulated workplace protection factors (SWPFs) between NIOSH-approved N95 respirators and P100 respirators, including two models of filtering facepiece respirator (FFR) and two models of elastomeric half-mask respirator (EHR), against sodium chloride particles (NaCl) in a range of 10 to 400 nm.Twenty-five human test subjects performed modified OSHA fit test exercises in a controlled laboratory environment with the N95 respirators (two FFR models and two EHR models) and the P100 respirators (two FFRs and two EHRs). Two Scanning Mobility Particle Sizers (SMPS) were used to measure aerosol concentrations (in the 10–400 nm size range) inside (Cin) and outside (Cout) of the respirator, simultaneously. SWPF was calculated as the ratio of Cout to Cin. The SWPF values obtained from the N95 respirators were then compared to those of the P100 respirators.SWPFs were found to be significantly different (P<0.05) between N95 and P100 class respirators. The 10th, 25th, 50th, 75th and 90th percentiles of the SWPFs for the N95 respirators were much lower than those for the P100 models. The N95 respirators had 5th percentiles of the SWPFs > 10. In contrast, the P100 class was able to generate 5th percentiles SWPFs > 100. No significant difference was found in the SWPFs when tested against nano-size (10 to 100 nm) and large-size (100 to 400 nm) particles.Overall, the findings suggest that the two FFRs and two EHRs with P100 class filters provide better performance than those with N95 filters against particles from 10 to 400 nm, supporting current OSHA and NIOSH recommendations.