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Some people find research boring.  We love it!  We've created this page for those that love it too.  Below are a few of the studies that have shown the effectiveness our technology in repelling particles and microbes, either without a mask or as a supplement to unfitted R95 masks that can leak significantly, rendering them extremely ineffective.  

Study: How To Increase The Protection Factor Provided By Existing Facepiece Respirators Against Airborne Viruses: A Novel Approach



Adverse health effects associated with airborne particles, including microbial and non-microbial aeroallergens, have recently gained considerable attention, especially due to increased reporting of respiratory symptoms in some occupational and residential indoor environments. The latest outbreaks of emerging diseases and the threat of bioterrorism have added some fuel to the problem. Although the transmission routes for some emerging diseases are still to be identified (e.g., SARS), many virus-induced health effects are known to be spread in the aerosol phase. Reducing the concentration of inhaled airborne particulates should reduce the risk of infection, as the number of cases among susceptible population is proportional to the average concentration of infectious droplet nuclei in a room and the probability that the particles will be inhaled. There is a special demand to increase the efficiency of existing respiratory protection devices, which otherwise may not provide an adequate protection against aerosol agents. Responding to this demand, we have developed and tested a new concept that allows to drastically enhance the protection factor provided by conventional facepiece filter respirators against submicron airborne particles (e.g., viruses). The concept is based on the continuous emission of unipolar electric ions in the vicinity of a respirator.


The new concept was tested in a non-ventilated indoor chamber (24.3 m3). An R95 respirator (3M 8247, 3M Company, St. Paul, MN, USA) was sealed to a manikin with silicone and petroleum jelly and connected to a breathing machine that operated at a constant air flow rate of 30 L/min. (inhalation). Prior to the start of data collection, leak tests (between the mask and the face of the manikin) were conducted with a bubble producing liquid (Trubble Bubble, New Jersey Meter Co., Paterson, NJ, USA). This experimental design allowed us to evaluate the enhancement effect of continuous emission of unipolar electric ions on the protection provided by the respirator filter (assuming that the particle penetration through the leaks was negligible). The viral-size particles (mid-point aerodynamic size da = 0.04-0.20 µm) were aerosolized into the chamber using a smoke generator. An Electrical Low Pressure Impactor (ELPI, TSI Inc./Dekati Ltd, St. Paul, MN, USA) was used to determine the concentration and aerodynamic particle size distribution in real-time. Aerosol sampling from outside and inside the respirator was alternated. Sampling lines and flow rates were identical up- and down-stream of the ELPI. The time resolution was adjusted to 10 seconds. The respirator protection factor was determined as a ratio of the measured aerosol concentrations outside (COUT) and inside (CIN) the respirator in 3 min. increments during a period of 12 min. The set-up is schematically presented in Figure 1. The background tests were performed in the absence of air ion emission. Then, a unipolar ion emitter (VI-3500*, Wein Products, Inc., Los Angeles, CA, USA) was turned on at 20 cm from the respirator, and the protection factor was determined in 3 min. increments during 12 min. of its operation. The emitter was characterized by measuring the air ion density at 1 m from the emission point using an Air Ion Counter (AlphaLab Inc., Salt Lake City, UT, USA). In addition, to the manikin-based experiments with a sealed respirator, human subject testing was also performed. In this phase of testing, the same model R95 filtering facepiece was worn by a test subject who was previously fit tested to this respirator using a TSI model 8020 Portacount (TSI, Inc). The fit testing protocol included standard head and breathing maneuvers required in the U.S. (normal and deep breathing, moving the face and the body left and right and up and down, talking, etc.). 


The protection factor measured with the respirator sealed on the manikin face was 73±6.0. We expected that it would exceed 20 since the R95 device should have at least 95% collection efficiency in the worst-case scenario. The emitter characterization tests showed that the density of negative air ions in the chamber increased rapidly, once it was turned on. It reached (1.340±0.037)x106 cm·3 during 5 sec., remained approximately at that level during a 30 min. continuous ion emission, and dropped to the initial level within 3 min. after it was turned off. Therefore, it was concluded that the experiments with respirators in the presence of the emitter were conducted at a constant air ionization level. 

It is seen that the respirator protection increased to 512±65 (enhancement of 7) as a result of a 3 min. ion emission in the vicinity of the respirator. Further ionization did not significantly change the enhancement of the respirator performance (p= 0.06). It is believed that since the particles and the filter fibers charged unipolarly by the ions, the repelling forces decreased the particle flow toward the filter. This reduced the number of particles that could potentially penetrate through the mask and be inhaled. The protection (fit) factors of the R95 respirator measured on the human subject ranged from 110 to 278, depending on the breathing procedure, with an average of 152, when no air ion emission was introduced. When the ion emitter was turned on, the fit factors ranged from 311 to 1380, with an average of 611, showing a 4-fold enhancement. The data suggest that faceseal leakage may somewhat reduce, but not eliminate, the effectiveness of respirator performance enhancement achieved due to the unipolar ion emission.


Continuous unipolar ion emission in the vicinity of a filtering facepiece respirator has the potential to drastically enhance performance against virus-size aerosol particles. 

Study: Respiratory Protection Against Airborne Biological Agents


Sergey A. Grinshpun and Tiina Reponen 


Facepiece respirators are widely used to reduce the human exposure with biological warfare or emerging diseases are primarily within the range of 30 run to 3 µm. Due to the threat of bioterrorism, the need to evaluate the performance of existing health-care masks and NIOSH­ certified N95 respirators and the demand to improve their efficiency have significantly grown. We have developed and built a sophisticated laboratory facility for evaluating various respiratory devices with bioaerosol particles and their surrogates using a manikin­ based protocol in a 25 m3 indoor chamber. The aerosol concentrations are measured real-time inside and outside the mask worn by a manikin. The measurements are conducted by a particle size selective aerosol spectrometer. The penetration efficiency is determined as a ratio of these concentrations for specific particle size fractions at different breathing flow rates. The data obtained with biological particles and their non-biological surrogates showed the limitations of existing respirators for reducing inhalation exposure to airborne spores and virions. We developed a novel concept for enhancing the collection efficiency of conventional filtering masks. The emission of unipolar electric ions in the vicinity of the mask was found to decrease the particle penetration through the filter by one to two orders of magnitude. Given that the infectious dose of many agents is· in order of 101 to 103 particles, the ion emission effect should make a crucial difference with respect to the exposure and health risk.

Study: Negative Air Ions and Their Effects on Human Health and Air Quality Improvement

International Journal of Molecular Sciences

Negative air ions (NAIs) have been discovered for more than 100 years and are widely used for air cleaning. Here, we have carried out a comprehensive reviewing on the effects of NAIs on humans/animals, and microorganisms, and plant development. The presence of NAIs is credited for increasing psychological health, productivity, and overall well-being but without consistent or reliable evidence in therapeutic effects and with controversy in anti-microorganisms. Reports also showed that NAIs could help people in relieving symptoms of allergies to dust, mold spores, and other allergens. Particulate matter (PM) is a major air pollutant that affects human health. Experimental data showed that NAIs could be used to high-efficiently remove PM. Finally, we have reviewed the plant-based NAI release system under the pulsed electric field (PEF) stimulation. This is a new NAI generation system which releases a huge amount of NAIs under the PEF treatment. The system may be used to freshen indoor air and reduce PM concentration in addition to enriching oxygen content and indoor decoration at home, school, hospital, airport, and other indoor areas.


Study: Evaluation of ionic air purifiers for reducing aerosol exposure in confined indoor spaces.

Indoor Air

Numerous techniques have been developed over the years for reducing aerosol exposure in indoor air environments. Among indoor air purifiers of different types, ionic emitters have gained increasing attention and are presently used for removing dust particles, aeroallergens and airborne microorganisms from indoor air. In this study, five ionic air purifiers (two wearable and three stationary) that produce unipolar air ions were evaluated with respect to their ability to reduce aerosol exposure in confined indoor spaces. The concentration decay of respirable particles of different properties was monitored in real time inside the breathing zone of a human manikin, which was placed in a relatively small (2.6 m3) walk-in chamber during the operation of an ionic air purifier in calm air and under mixing air condition. The particle removal efficiency as a function of particle size was determined using the data collected with a size-selective optical particle counter. The removal efficiency of the more powerful of the two wearable ionic purifiers reached about 50% after 15 min and almost 100% after 1.5 h of continuous operation in the chamber under calm air conditions. In the absence of external ventilation, air mixing, especially vigorous one (900 CFM), enhanced the air cleaning effect. Similar results were obtained when the manikin was placed inside a partial enclosure that simulated an aircraft seating configuration. All three stationary ionic air purifiers tested in this study were found capable of reducing the aerosol concentration in a confined indoor space. The most powerful stationary unit demonstrated an extremely high particle removal efficiency that increased sharply to almost 90% within 5-6 min, reaching about 100% within 10-12 min for all particle sizes (0.3-3 microm) tested in the chamber. For the units of the same emission rate, the data suggest that the ion polarity per se (negative vs. positive) does not affect the performance but the ion emission rate does. The effects of particle size (within the tested range) and properties (NaCl, PSL, Pseudomonas fluorescens bacteria) as well as the effects of the manikin's body temperature and its breathing on the ionic purifier performance were either small or insignificant. The data suggest that the unipolar ionic air purifiers are particularly efficient in reducing aerosol exposure in the breathing zone when used inside confined spaces with a relatively high surface-to-volume ratio.


Study: Air Pollution XII



Wessex Institute of Technology, UK

S. A. Grinshpun, A. Adhikari, B. U. Lee, M. Trunov, G. Mainelis, M. Yermakov & T. Reponen





Various health effects are associated with or directly caused by respirable airborne particles and microbial agents. To reduce the human exposure to these indoor pollutants, numerous techniques have been developed over the years. In this study, we have investigated the effect of unipolar air ionization on airborne dust particles and microorganisms in indoor environments. The concentration and particle size distribution were measured in real time using optical and aerodynamic particle counters with a special focus on the bacterial particle size range of 0.5 to 2 µm.   The tests were conducted  in three indoor chambers of different  volumes (ranging from 26 L to 24.3 m3)  at different  ion  emission rates (producing air ions at ~104 to ~l05 ions/cm3 as measured at ~1 m from the source). The concentration decay occurring due to ionic emission was compared to the natural decay for four types of challenge aerosols. Resulting from the interaction with unipolar air ions, airborne particles exhibited considerable electric charges of the same polarity as the emitted ions. Due to electrostatic repelling forces, the particles migrated toward the indoor surfaces and rapidly deposited on these surfaces. Two small, battery operated ionic emitters tested in this study showed significant air cleaning efficiency for respirable (sub- and super-micrometer) particles. This effect was more pronounced in smaller air volumes. The efficiency of ion emission in reducing the viability of airborne microorganisms in indoor air was also evaluated in a specially designed set-up.  Two species of Gram-negative bacteria (Pseudomonas fluorescens and Escherichia coli) and one species of Gram-positive bacteria ( Staphylococcus epidermidis) were tested. It was found that a significant percentage of airborne viable bacteria could be inactivated by the ion emission: up to 92% of E. coli was inactivated during a one-minute exposure in dry air. It was concluded that the ion-driven decrease in the aerosol concentration combined with the bactericidal effect can significantly reduce human exposure to indoor air pollutants, such as particles and microorganisms.