Efficacy Comparison of Household and Clinical Options for Facemask Materials With a Disposable N95 Mask.

Non-pharmaceutical interventions have been recommended when viruses spread on local, regional, and global levels.  The mask-wearing culture in northeastern Asian countries, one of the non-pharmaceutical interventions, may assist in the reduction of the viruses’ spread during pandemics. The main objective of our study was to test the efficacy of different materials available for facemasks/coverings by comparing their filtration efficiencies and airflow resistances to that of a disposable N95 mask. The tested materials were categorized into two groups: clinical and household materials. In the clinical material category, we tested disposable surgical facemasks, imported facemasks (KN95), and surgical and sterilization wraps. In the household material category, we tested cotton T-shirts and commercial fabric materials. The materials were selected based on their popularity, ease of access, and potential to replace the N95 facemask. By providing the general population with the efficacy of each accessible facemask option, individuals will be able to make an educated decision to protect themselves from airborne viruses.  The circular-shaped test specimens of facemask materials were prepared for a filter holder (Whatman Filter Holder, Polysulfone in-line filtration 50 mm). The airflow resistance measurement system included a rotameter, a facemask sample holder, and a manometer. The filtration efficiency test system consisted of a Constant Output Atomizer (COA, TSI Aerosol Generator 3076), diffusion dryer, 85Kr neutralizer, facemask sample holder, Wide-range Particle Spectrometer (WPS - 1000XP), flowmeter, and vacuum pump. This setup allowed the facemask sample material to work as a “filter” as it provides the barrier to the transport of aerosol particles.  Nanometer to micrometer-sized aerosol particles were generated from the COA. The particle concentrations were measured at the upstream and downstream locations of the facemask sample. The efficacy of various facemask materials was compared with disposable N95 masks and the surgical facemasks based on the facemask resistance to airflow (Rfilter) and the filtration efficiency (FE). The total FE (FETotal) and the FE for airborne particles (FEAirborne) were evaluated for a controlled environment with a wide range of particle sizes (i.e., 10 to 10000 nm in diameter (dp)) and airborne aerosols (i.e., 282.62 < dp < 332.65 nm), respectively.  The Rfilter for the N95 mask was significantly higher than all other mask materials tested. The breathability, determined by Rfilter, of the N95 mask is the most difficult implicating the other materials are all capable of comfortable human breathability at a moderate or high work rate, approximately 85 LPM. It is concluded that the facemask materials tested are eligible as an alternative. The disposable N95 and KN95 facemasks showed the best FE (FE>97%) for the entire particle range. The sterilization wrap (FETotal = 85.1%, FEAirborne = 87.1%) and the double-layered cotton T-shirt (FETotal = 61.3% and FEAirborne = 75.8%) showed the highest FE in the clinical and household settings, respectively. The sterilization wrap and the double-layered cotton T-shirts could be considered as personal protective equipment alternatives for the N95 facemask in both clinical and household settings. The current findings result in a good indication of the efficacy of the facemask material. The next step in pursuing a more holistic understanding of how facemasks stop the spread of airborne viruses is to investigate the effects of the fit of the mask in addition to the spacing and orientation of people. The findings of this future study will be extremely beneficial to society in light of school and business reopenings.