Performance Evaluation of Selected N95 Respirators and Surgical Masks When Challenged with Aerosolized Endospores and Inert Particles

Abstract

The objective of this study was to assess how the relative efficiency of N95 respirators and surgical masks might vary with different challenge aerosols, utilizing a standardized manikin head form as a surrogate to human participation. A Collision nebulizer aerosolized B. anthracis Sterne strain endospores and polystyrene latex (PSL) particles to evaluate 11 models of N95 respirators and surgical masks. An automated breathing simulator, calibrated to normal tidal volume and active breathing rate, mimicked human respiration. A manikin head form with N95 respirators or surgical masks, and manikin head form without N95 respirators or surgical masks were placed in the bioaerosol chamber. An AGI-30 sampler filled with phosphate buffered water was fitted behind the mouth of each manikin head form to collect endospore bioaerosol samples. PSL aerosols concentrations were quantified by an ARTI Hand Held Particle Counter. Geometric Mean (GM) relative efficiency of N95 respirators and surgical masks challenged with endospore bioaerosol ranged from 34-65%. In PSL aerosol experiments, GM relative efficiency ranged from 35-64% for 1.3 μm particles. GM filtration efficiency of all N95 and surgical N95 respirators filter media evaluated was ≥99% when challenged with particles ≥0.1 μm. GM filtration efficiency of surgical mask filter media ranged from 70-83% with particles ≥0.1 μm and 74-92% with 1.3 μm PSL particles. Relative efficiencies of N95 respirators and surgical masks challenged with aerosolized B. anthracis endospores and PSL were similar. Relative efficiency was similar between N95 respirators and surgical masks on a manikin head form despite clear differences in filtration efficiency. This study further highlights the importance of face seal leakage in the respiratory protection provided by N95 respirators, and demonstrates it on a human surrogate.

Effectiveness of activated carbon masks in preventing anticancer drug inhalation

“…However, the three mask types used in this study were not examined with regard to the N95 criteria. Generally, the filtration efficiency of pleats-type surgical masks, for particles with >0.1 μm diameter, is approximately 20–30 % lower than that of the N95 mask [16]. Furthermore, a leak may result from a gap between the face and the mask, depending on mask design and appropriate use by the healthcare worker, subsequently affecting filtration efficiency.…”

Performance of Composite Filters Assembled from Multiple Layers of Basic Filtration Media

“…The pros and cons of this strategy have not been scientifically investigated to the authors' knowledge (although the general rule of thumb is known). The objectives of this study are thus to (1) directly compare the filtration performance of FFRs and surgical masks under the same testing protocol using NaCl particles to represent virus particles (Eninger et al, 2008;Davidson et al, 2013); (2) study the filtration performance of composite filters, assembled by loosely layering multiple layers of basic filtration media that are readily available in the market; and (3) examine the additivity of the filtration performance of the above composite filters. Fig.…”

Respiratory Flow Characterization of Workers in Healthcare Environment

“…There are 18 million U.S. healthcare workers (HCWs) relying on personal protective equipment (PPE) (CDC, 2014). Various studies have shown surgical masks offer minimal protection and that N95 filtering facepiece respirators (FFRs) are not comfortable to use (Davidson et al 2013;He et al 2013a b;2014;Rengasamy et al 2014). Since the outbreaks of 2003 SARS, 2009 H1N1, and 2015 Ebola, more and more attentions have been attracted towards using powered air purifying respirators (PAPRs) for HCWs (IOM, 2015).…”

“…when exposed to a range of known and unknown occupational infectious agents (CDC, 2014). Traditionally, surgical masks and N95 filtering facepiece respirators (FFRs) are widely used to reduce exposure to airborne hazards in healthcare settings, even though various studies have demonstrated that surgical masks offer minimal protection and N95 FFRs are not comfortable to use due to the high air resistance of the filter (Davidson et al, 2013;He et al, 2013b;He et al, 2014;Rengasamy et al, 2014). Following the 2003 severe acute respiratory syndrome (SARS), 2009 H1N1 influenza, and the recent Ebola outbreak, significant attention has been directed towards using powered air-purifying respirators (PAPR) for HCWs (IOM, 2015).…”

“…Surgical masks and N95 filtering facepiece respirators (FFRs) are traditional respiratory protection equipment (RPE) used by HCWs in hospital environment (Carias et al, 2015;Wizner et al, 2016). However, various studies have shown that surgical masks are not designed to protect against bioaerosols <1 µm, and N95 FFRs are not comfortable to use due to high breathing resistance (Davidson et al, 2013;He et al, 2013b;2014;Rengasamy et al, 2014). Frequently outbreaks of highly contagious pathogens (e.g., 2003SARS, 2009H1N1, and 2014 have emphasized the need of powered air-purifying respirators (PAPRs) for HCWs (Khoo et al, 2005;IOM, 2015;Wizner et al, 2016).…”