Filtering Efficiency of N95- and R95-Type Facepiece Respirators, Dust-Mist Facepiece Respirators, and Surgical Masks Operating in Unipolarly Ionized Indoor Air Environments

Abstract

The emission of unipolar air ions in the vicinity of a filtering facepiece respirator has been recently shown to considerably enhance its respiratory protection efficiency. The effect is driven by the electric repelling forces that develop between the unipolarly charged mask and the aerosol particles, thus creating a shield for the incoming particles and consequently decreasing the penetration efficiency through the filter. The manikin-based preliminary evaluation of this concept has been performed with a very limited number of variables. In this study, four types of half-mask facepiece filtering devices (N95, R95, and dust-mist respirators, as well as surgical masks), operating at two different breathing flow rates, were tested with unipolar air ion emitters exhibiting different emission rates and polarities. The particle penetration efficiency through the facepiece filter was determined in a room-size indoor test chamber by a real-time particle size selective aerosol monitoring performed inside and outside of the mask, which was face-sealed onto a manikin. Three commercially available ionic air purifiers were utilized as air ion emitters. For the targeted particle size range of ~0.04 -1.3 µm, a 12-minute air ionization in the vicinity of a manikin enhanced the respiratory mask performance by a factor ranging from 1.61 to 3,250, depending on the respirator type, breathing flow rate, and the ion emission rate. The effect was achieved primarily within the first 3 minutes.

Mask Material Filtration Efficiency and Mask Fitting at the Crossroads: Implications during Pandemic Times

“…Whereas some studies use a manikin headform with the full mask (Balazy et al, 2006a,b;He et al, 2013;Bahloul et al, 2014;Shakya et al, 2016;Adhikari et al, 2018;Kumar et al, 2020), other studies cut a portion of the mask/fabric and place it in a filter holder (Eshbaugh et al, 2008;Lin et al, 2017;Konda et al, 2020;Pei et al, 2020;Wang et al, 2020). Many studies use salt, e.g., NaCl (Eshbaugh et al, 2008;He et al, 2014;Lin et al, 2017;Pei et al, 2020), or polystyrene latex (PSL) spherical particles of defined sizes (Qian et al, 1997;Lee et al, 2005;Eshbaugh et al, 2008) to simulate particulate contaminants. The particle concentration used in these experiments varies from hundreds to several tens of thousands of particles per cm 3 (Balazy et al, 2006a,b;Eshbaugh et al, 2008;He et al, 2014;Adhikari et al, 2018).…”

“…common flow rate is 85 L min -1 , which represents breathing under heavy workload, similar to the condition defined by NIOSH (NIOSH, 2020). Lower flow rates are also commonly studied such as 15 and 30 L min -1 that represent breathing under light workload (Lee et al, 2005;Balazy et al, 2006a,b;He et al, 2013;2014).…”

Life Comes from the Air: A Short Review on Bioaerosol Control

“…Artificial ion emission treatment of filters was found to increase the filtration efficiency of aerosol particles and decrease bioaerosol activity on filters (Lee et al, 2004a;Lee et al, 2005;Huang et al, 2008;Park et al, 2009). However, artificial ion emission can result in unnecessary ozone production as well as accumulation of electric charges and electric shock in nearby environments.…”

Filtration of Submicron Aerosol Particles Using a Carbon Fiber Ionizer-assisted Electret Filter

“…Park et al (2011) tested the increase in particle filtration with a pair of carbon fiber ionizers installed upstream of a glass fiber air filter. Lee et al (2004Lee et al ( , 2005 used facepiece respirator filters and continuous emission of unipolar air ions by coronaionizing air purifiers in the vicinity of a disposable halfmask respirator enhanced its protection characteristics against fine and ultrafine particles of bacterial and viral size ranges. Agranovski et al (2006) used low efficiency heating, ventilating, and air conditioning (HVAC) air filters.…”