ION Clairety LLC Scientific Article

Protection from Airborne Contaminants -Limitations of Masks and Respirators with Comparison to Novel Filtering Materials and Designs

 Summary:

   Novel designs and materials were investigated to overcome limitations of conventional face filtering devices. Surgical masks and N95 respirators filter primarily by mechanical trapping of particles on the filter fibers. Filtration efficiency depends on a tight face fit.  Because of comfort issues, a tight fit is difficult to achieve and maintain in practical use resulting in filter efficiencies significantly lower than claims.  For example, the bacteria filtration efficiency test specified by the FDA for N95 certification is performed using an airtight glued peripheral seal around the testing apparatus. Such a perfect seal condition only determines the inherent efficiency of the filter matrix. In actual use some air escapes filtration around the filter periphery resulting in filtration less than the 95%. To obtain data relevant to actual use, a head form manikin was fitted to simulate the range of practical fits achieved by human subjects in workplace conditions. In addition to conventional testing methods using NaCl (Sodium Chloride/salt) particles, bacteria and breathability measurements, the authors developed other analytical methods and apparatus to measure virus filtration, exfiltration efficiency (the ability to protect the public from infected wearers), physiological effects on respiration rate, heart rate and blood oxygen. The expanded repertoire of test methods was used to evaluate new designs and filtration materials under practical fit conditions.  A novel approach based on laws of electro physics termed “ion capture” was discovered to yield significant improvements in filtration efficiency, comfort, and ease of fit. Ion capture uses alternating layers of open weave, breathable fabrics, one with a permanent positive and the other a permanent negative ionic charge.  The fabrics were incorporated into two face covering designs, a gaiter-like design pulled over the head, and a “wrap” design in which the open-ended garment is wrapped around the neck and simply attached at the back of the neck with “hook & loop” material. Elastic bands sewn between fabric layers comfortably seal the fabric 360 degrees around the upper face and neck areas providing a much larger filter surface area compared to conventional mask designs. In addition, a molded, soft foam nose piece inserted between fabric layers fills the gaps commonly seen around the sides of the nose, cheeks and chin areas of conventional face masks. These new design features effectively eliminate the significant volume of air evading filtration as seen in conventional masks due to air entry and exit around mask edges. The ION Gaiter and ION Wrap designs were comprehensively compared to the N95, surgical masks and a representative sampling of uncertified, post COVID-19 inspired, mechanical filtering mask designs. Ion capture technology yielded average filtration efficiencies over 99% compared to approximately 80% and 40% for the N95 and surgical masks under practical fit conditions. Newer unregulated mask designs incorporating silver, zinc and/or copper impregnated fabric claiming to kill microbes did not perform significantly better than the 40% filtration of surgical masks. Cloth masks with non-woven filter inserts paradoxically filtered at less than 40% due to the further air flow inhibition caused by the filter insert resulting in more unfiltered air going around the edges of the masks.

Introduction:

   The COVID-19 pandemic not only caused a shortage of approved, medical-grade face filtering devices (FFD) such as surgical masks and N95 respirators but at the same time exposed limitations of conventional FFD in terms of protection (filtration efficiency), breathability, comfort and difficulties in achieving and maintaining a tight fit to the face during use. The shortage of FFD resulted in many new designs entering the market along with home-made masks. These FFDs range from single-use, mask-like designs made from non-woven polymer materials to reusable cloth masks. Many new devices make dubious claims not rigorously tested under actual fit conditions. FFD for use in medical venues are regulated by the FDA and National Institute of Occupational Safety and Health (NIOSH) with guidelines published in the Code of Federal Regulations.^1,2  Recognizing the shortage of FFD for the general public the American Society for Testing and Materials published a new standard early in 2021, ASTM F3502-21 that has been recognized by the FDA to help the general public make informed decisions when selecting barrier face coverings.

  Surgical masks and N95 respirators function by mechanical filtration with particles becoming trapped on the non-woven fiber matrix. Our initial testing of regulated devices as well as the many new designs coming on the market during the COVID-19 pandemic, confirmed limitations in providing higher levels of protection are due primarily from problems in achieving and maintaining a good, comfortable fit around the face. In addition, to standard test methods used to approve current FFD, ION Clairety developed other test methods allowing for a more comprehensive evaluation of multiple performance parameters that were quantitatively measured under actual fit and wearing conditions. In the course of testing conventional devices and evaluating novel materials and designs, we discovered some materials containing  permanent positive and negative ionic charges that significantly out-performed conventional mechanical FFD while also providing better comfort and ease of fit. This study compares the performance of surgical masks and N95 respirators to non-traditional materials and designs utilizing principles of electro physics termed “ion capture”. 

Surgical masks

   Surgical masks can filter some airborne microbes reducing disease transmission, but they are not certified for protection from inhalation of airborne disease. MacIntyre and Chughtai (2015)³ published a review of FFD types. A more important function of surgical masks is to minimize microbes shed by the wearer from talking, sneezing and coughing as studied by Leung et al (2020).⁴ Conventional surgical masks consist of one or more layers of a non-woven, synthetic polymer filter matrix and cotton held in place over the nose and mouth by loops placed over the ears. The relative loose fit of the mask design allows some microbes to evade filtration by entering or exiting around the periphery. The shortage of FFD caused by the COVID-19 pandemic resulted in manufacturers from other industries re-tooling to meet demand along with home-made woven cotton masks. Most new devices are unvalidated and some offer misleading claims not rigorously tested under actual fit conditions. Because these devices are fundamentally mask designs, they will be limited in achieving high filtering efficiencies due to poor fit. This statement is supported in a review article by ben-Reza et al (2011)⁵ that FFD efficacy is linked to relevant fit testing and correct usage.

The N95 respirator

   When properly fitted the N95 provides higher levels of filtration primarily due to a tighter fit achieved by a foam-backed, fitted metal nose piece and high-tension elastic bands. The critical specification for N95 respirators is a filtration efficiency of >95% for particle sizes ≥ 0.3 microns. Description of the current testing apparatus and methods can be obtained through the National Personal Protective Technology Laboratory (NPPTL).⁶ Particle filtration testing specified for regulatory certification utilizes non-hazardous NaCl particles under the arguable assumption that all particles such as bacteria and very small virus should filter at similar efficiencies.  For the current test a 2% NaCl solution is nebulized into the test chamber, hot-air dried and pulled through the filter.  This apparatus generates NaCl particles over a range of sizes that can be quantitated using a laser particle counter. Lee, Grinshpun and Reponen (2008)⁷ concluded N95 respirators provide better protection than surgical masks but under actual wearing conditions the practical filter efficiencies are less than the 95% determined using a perfect seal. It has been reported that particles smaller than 0.3 microns do not filter as well as NaCl and that there is considerable performance variability between approved N95 respirators. Best fit is critical to achieve maximal filtration efficiency but difficult to obtain and maintain. Efforts to improve fit create several objections from wearers. The major limitation of mechanical filtration is that the filter matrix composed of tightly compacted, meltblown and spunbound plastic polymer fibers inhibits air flow and creates breathability problems. Restriction of breathing is problematic for people with respiratory and heart problems contraindicating mask use. Li and Tokura (2005)⁸ and Zhu, Lee, Wang, and Lee (2014)⁹ reviewed effects on heart rates, respiration resistance objections, and other negative sensations. Ong et al (2020, 876)¹⁰ reported de novo and exacerbated headache in health care workers from long-term compression around the head and face further concluding that “better strategies are needed for designing various personal protection equipment”. Tight elastic bands and pinched nose pieces cause skin irritations. Heat, moisture and odor accumulation inside the mask result in non-compliance for proper fit. Exhaled air escaping around mask edges fogs eyeglasses, goggles, and face shields. Regulations require the wearer be trained on proper use and to perform a fit test each time the N95 is donned.

Ion capture filtration

     Several non-traditional filtering materials and face cover designs were comprehensively tested in our labs as described in the “Methods “section below. The most promising new technology to emerge is described as ion capture filtration (ICF).  ICF achieves filtration by exploiting principles of electro-physics. No device is currently certified using the principles of ICF. Two patent pending ICF designs, called the ION Gaiter, and ION Wrap developed by ION Clairety LLC were compared to the N95 and consistently showed superior filtration efficiency, breathability and comfort.

     ICF should be distinguished from the very broadly encompassing term “electrostatic” used in reference to a variety of physics phenomena from inter-molecular bonds to voltages generated by rubbing two dissimilar materials together also termed “triboelectric effect”. Electrostatic interactions are complex and beyond the scope of this paper, but the following basic principles are offered for background. Electrostatic attraction forces are given by Coulomb’s law (F=kq₁q₂/r²). When applied to particle filtration, mechanical physics must also be considered due to the kinetic energy of the particle being filtered. Kinetic energy is described by the equation K_e = 1/2mv².

   Some mechanical filtration devices make unsubstantiated claims of increased performance due to static electricity properties of the filter matrix. Our testing of these filter matrices concluded that the electrostatic forces of meltblown polymer fibers as well as most natural fibers like cotton or wool are weakly charged and that charge is effectively neutralized by the wearer’s breath and as such do not significantly augment filtration efficiency. Using an electrostatic meter configured to measure surface static charge we observed that the low negative charge of an unused N95 mask became un-measurable by the wearer’s breath. The particle filtration efficiency of a freshly opened N95 with low but measurable electrostatic charge was compared to an N95 with the charge neutralized by five respirations of a human subject. There was no significant change in filtration efficiency indicating mechanical filtration is the dominant mechanism of filtration for conventional non-woven masks. When considering use of an FFD claiming electrostatic filtration benefits, but without data collected under relevant user conditions, any claims of electrostatic benefit are dubious and may lead to a false sense of security by overstating the practical filtration efficiency.

     ICF forces are utilized in other scientific areas. In the fields of vaccine production, gene therapy and virus purification, the biopharmaceutical industry utilizes a technique termed “ion exchange chromatography” to purify viral products or remove virus contaminants. ICF pulls the virus or other charged particle out of a liquid stream immobilizing it onto an oppositely charged chromatography matrix. Other components with lesser or opposite charge flow through the matrix resulting in virus purification. Release of ionic bound material is accomplished by treatment with reagents to neutralize charge such as salt solutions, pH changes, or surfactants like detergents to regenerate the chromatography support for reuse. ICF is fundamentally the same as liquid chromatography except contaminants are pulled out of an air stream.

     ICF relies on the selection or covalent chemical modification of fabrics for permanent ionic charge. A permanent charge is created by covalent molecular bonds to generate permanent polyatomic ions that are not practically affected by humidity or relevant atmospheric conditions. The Ion capture filter matrix in the ION Clairety gaiter, wrap and scarf designs uses 2 different woven fabrics in 3 layers. A fabric with high density, polyatomic cations (positive charge) is sandwiched between 2 fabrics containing polyatomic anions (negative charge).  ICF technology exploits the fact that microbes and many other airborne contaminants have negative and/or positive ionic charges and as such can bind to both positive and negative charged sites on the fabrics. ICF forces operate over distances up to several millimeters as predicted by Coulomb’s Law. This strong attraction allows use of open-weave fabrics to achieve efficient removal of particles. Open weave fabrics reduce restriction of breathing compared to mechanical filtration. With air passing more easily through the fabrics, less unfiltered air escapes around the periphery. Another important design feature of the ION Gaiter and Wrap is a molded, soft foam insert sewn between the layers of fabric designed to close the gaps around the sides of the nose responsible for the reduced filter efficiencies of conventional mask designs. No special fitting or training is required. The ION Clairety garments rest comfortably around the neck when not needed and are deployed by simply pulling up over the nose. The ION Clairety designs protect a greater area of skin due to encircling the neck and face while providing more than 3 times the filtration surface area of conventional masks.

Methods

N95 fit testing

     A 3M N95, model 8210 was used in this experiment. An anatomically representative, soft silicon covered head form manikin was developed to test filtration as a function of fit. Holes in the nose and mouth of the manikin join to a sinus-like cavity inside the head connected by tubing through the rear of the manikin to an external laser particle counter. A study published by Bergman et al (2015)¹¹ using a similar manikin apparatus concluded it represents filtration performance on human subjects. Room air containing a heterogenous size array of particle types from dust to microbes was used as the source of particles. Particles were counted using a Beckman Coulter MET ONE HHPC 2+ laser counter at a flow rate of 2.8 liters/min approximating the breathing volumes of at-rest subjects. This instrument counts particles in the size range of 0.1 to 10 microns, sizes inclusive of bacteria, mold, fungus, and virus associated with mucosal aerosols. Particle counts were measured under conditions described as “Poor fit”, “Practical fit”, and “Perfect seal”. The “Poor fit” is evidenced by observations of small gaps (<2mm) between the respirator and skin as is commonly seen when the nose piece is not tightly fitted or the mask not properly sized. The “Practical fit” was achieved with the N95 optimally fitted per instructions with the nose piece carefully adjusted and the elastic bands stretched at high tension, one over the head and the other around the neck under the ears. No visible gaps were observed. The “Perfect seal” data shows the inherent ability of the matrix to filter out particles by sealing the circumference of the N95 with glue, a condition not achieved in actual wear.

Filtration of individual airborne contaminants

     Particle filtration efficiencies for regulated devices are routinely determined using NaCl particles injected into an automated mechanical apparatus with a swatch of the filter material perfectly sealed by glue to eliminate leakage around the periphery. It is arguable how well these conditions represent performance for microbes and other disease-causing particulates. This study was designed to measure filter efficiencies of environmentally relevant particles under actual use conditions. Particles in liquid and dry aerosols were tested using the MET ONE HHPC 2+ instrument connected to the manikin placed inside a 12liter conical chamber.  A known mass of dry challenge particles is incrementally aerosolized into the top of the chamber. Particles evading filtration are counted for 5 minutes. The N95 “Perfect seal” and “Practical fit” was accomplished as previously described. ION Gaiter fit involves first pulling it over the head down to the neck. When needed the gaiter is simply pulled up and over the nose. The foam insert over the upper face and 360°degree elastic neck band provide a reproducible, best-fit that does not require additional fit adjustment. Total inoculant counts were first performed without a mask to allow for calculations of efficiency. The manikin chamber apparatus allows for safe testing of bacteria, virus, mold and fungus and dry particles like talc, pollen, and hazardous industrial dusts under realistic wearing and fit conditions.

Microbial detection

     Microbial challenge was performed using a microbial air sampling instrument (IUL Spin Air sold through Neutec Group, Inc.) certified for testing in laboratories and drug manufacturing facilities. The manikin is placed inside a 12L conical chamber and connected by tubing to the air sampler outside the chamber with an air flow volume of 10L/min. Aerosolized suspensions of challenge microbes in ~125µL are introduced by a nebulizing spray bottle into the top of the chamber under negative pressure provided by the air sampler providing a heterogeneous array of aerosol sizes similar to those emitted by talking, sneezing, and coughing. Air passing through or around the filter is routed by tubing through the manikin into the IUL Spin Air sampling unit rotating at 4 rpm. This apparatus plates bacteria onto a petri dish with TSA Agar as the growth medium. Three petri dishes were inoculated for each test condition. Inoculated plates were placed into a 30°C incubator. Colony forming units (CFUs) were counted after 48 hours of culture. Total CFUs in the 3 plates are recorded in Table 2. The calculation of % reduction was determined by dividing total CFUs for each face covering by the control CFUs without a mask.

Virus filtration

     To allow for safe testing, a non-infectious virus particle termed Minute Virus of Mice (MVM) used by the biopharmaceutical industry to demonstrate viral clearance from the purification of biopharmaceuticals, was inoculated as a liquid aerosol into the manikin chamber as previously described. MVM evading filtration is captured on a non-permeable ionic membrane, eluted from the membrane using a 0.5M NaCl salt solution and then tested in a quantitative immuno-PCR assay kit available from Cygnus Technologies, LLC in Southport, NC. Filtration percent is calculated against the unmasked control.

Breathability/Comfort

     Breathability is measured as pressure drop across a filter matrix using a dual port manometer (Fieldpiece Model SDMN5) following protocols referenced by NPPTL. Measurements were taken at a flow rate of 2.8L/min through 1.22cm² of filter surface. The N95 and ION Gaiter filter materials were sealed ensuring air can only flow through the filter. Units of measurement are centimeters of water.  Because restriction of air flow can be a systemic health issue, physiological data was collected on human subjects with and without face covering devices for respiration rate, pulse rate and oxygen saturation using a finger-tip pulse oximeter.

Exfiltration - protecting the public from infected persons

     Personal protection devices should not only protect the wearer from airborne contaminates, but when worn by an infected person should minimize microbes shed into the air. FFD approved for medial use are not routinely tested for exfiltration. We designed an apparatus to allow for quantitative measurement of particle exfiltration under practical wearing conditions. Experiments were performed in a HEPA filtered lab to minimize background counts. Test particles are micronized benzocaine powder suspended in a solution of water, glycerol, isopropyl alcohol and cyclomethicone to simulate the density, viscosity, and surfactant properties of mucosal secretions. The benzocaine challenge solution contains a heterogeneous range of particle sizes from <0.1 to >1.0 micron. Particles were nebulized by spraying into a dosing tubing at the back of the manikin. The force used to expel the test particles is provided by a human subject coughing into the 1.6cm diameter tubing immediately after particles were introduced into the dosing tubing. The cough forces the challenge solution through the manikin and out the nose and mouth openings. The laser particle counting device was placed in the lab 2 feet from the manikin face. Background counts were measured before each experiment and subtracted from readings in Table 5. Exfiltrated particles were counted for 5 minutes.

Results

N95 filtration efficiency as a function of fit

     Averages were determined from 10 repeats of each fit condition. Filtering efficiency of “Poor     fit” N95’s averaged 46.8%. “Practical fit” averaged 80.1%. “Perfect seal” filtered 97.4% in   reasonable agreement with the NIOSH specification of >95%.

Filtration efficiencies of individual particles types

   Table 1 compares of efficiencies of N95 fits, surgical masks and the ION Gaiter challenged    with environmentally relevant particle types.  The “office air” experiment represents a heterogeneous mixture of airborne contaminants as might be found in workplaces. The ION Gaiter provided filtering efficiencies from 98.0 to 99.9% for all challenge particles. The “Perfect seal” of the N95 mask gave efficiencies ranging from 92.8 to 99.7%. The N95 “Practical fit” efficiencies ranged from 73.5% to 93.8%. The surgical mask consistently yielded poorest filtrations ranging from 24.3% to 81.8%.

 Table 1:  Filtering efficiency comparisons for relevant particles

Filter device & fit	Challenge particle	% Removal of particles 0.1µ to 0.5µ in Size	% Removal of particles > 1µ to 10µ
ION Gaiter	Aspergillus niger fungus spores	99.0	99.2
N95 Perfect seal	“	92.8	93.3
N95 Practical fit	“	80.2	80.0
Surgical Mask Practical fit	“	57.2	58.1
ION Gaiter	Penicillium brevi mold spores	99.8	99.8
N95 Perfect seal	“	94.5	94.5
N95 Practical fit	“	73.5	74.5
Surgical Mask Practical fit	“	53.2	55.2
ION Gaiter	Wood ash	99.6	99.7
N95 Perfect seal	“	97.8	98.2
N95 Practical fit	“	79.5	83.5
Surgical mask Practical fit	“	32.7	43.2
ION Gaiter	Talcum powder	99.8	99.9
N95 Perfect seal	“	98.1	98.1
N95 Practical fit	“	77.0	76.6
Surgical mask Practical fit	“	69.8	69.1
ION Gaiter	Tree pollen (mixture oak & pine)	99.8	99.7
N95 Perfect seal	“	99.7	99.6
N95 Practical fit	“	94.3	94.5
Surgical mask Practical fit	“	42.5	43.5
ION Gaiter	Stone cutting dust	99.7	99.8
N95 Perfect seal	“	99.4	99.4
N95 Practical fit	“	91.1	91.3
Surgical mask Practical fit	“	80.1	81.8
ION Gaiter	Cement dust	98.0	98.4
N95 Perfect seal	“	99.0	99.1
N95 Practical fit	“	93.8	93.7
Surgical mask Practical fit	“	Not tested	Not tested
ION Gaiter	Plaster/Dry wall dust	99.4	99.6
N95 Perfect seal	“	99.0	99.1
N95 Practical fit	“	89.6	90.3
Surgical mask Practical fit	“	41.0	43.2
ION Gaiter	Office air	98.3	98.4
N95 Perfect seal	“	96.6	98.2
N95 Practical fit	“	81.7	83.5
Surgical mask Practical fit	“	24.3	33.2

 

Bacteria filtration

     Table 2 shows filtration efficiencies of Staphylococcus epidermidis suspended in a phosphate buffered saline and inoculated by fine spray aerosolization into the top of the manikin test chamber. 

 Table 2 – Bacteria filtration efficiencies of filter devices

Filtration device	Total CFUs	% Reduction        from control
No mask, control	196	NA
ION Gaiter	1	99.5
N95 Perfect seal	9	95.4
N95 Practical fit	26	86.7
Surgical mask	150	23.5

 

Virus filtration

      The ION Gaiter captured 99.4% compared to 92.7% for a “Practical fit” N95. Since virus evading filtration has the potential to cause infection, a more direct way to calculate efficiency is to compare what gets through a filter. For example, the N95 failed to filter 7.3% of the virus while the ION Gaiter failed to filter 0.6%. Analyzing data in this way, the ION Gaiter provided a 12.2-fold reduction in unfiltered virus compared to the N95 (7.3%/0.6%=12.2).

      There are few studies demonstrating the quantitative efficiency of conventional masks for filtration of virus. Virus particles typically have sizes in the range of 0.01 microns calling into question if the 95% filtration specification of ≥0.3 microns for NaCl particles represents virus filtration efficiency. Studies by Loeb et al (2009)¹² and Radonovich et al (2019)¹³ performed on health care workers during influenza outbreaks compared the N95 and surgical masks using cell culture and PCR for detection. Noti et al (2012)¹⁴ compared virus filtration of surgical masks to the N95 as a function of fit concluding that virus filtration efficiencies are dependent on fit and training. In his study a glue sealed N95 gave 99.6% filtration while an N95 fitted to simulate how they are worn by health care workers filtered significantly less at 66.5%. The surgical mask filtered 56.6% of virus.

Breathability testing

   The pressure drops for the N95 and ION Gaiter were -2.97 and -0.45 cm of water respectively demonstrating a 6.6-fold less pressure drop for the ION Gaiter. In actual wearing conditions, the lack of a “Perfect seal” for the N95 mask will increase its perceived breathability but at the cost of filtration efficiency.

      Restricted breathing can manifest as increased respiration and heart rates and lower blood oxygen preventing some individuals from wearing face masks. Table 3 contains data on average respiration rate, pulse rate and arterial blood oxygen saturation over 5 minutes for 3 healthy male and 2 female subjects at rest. The N95 used a “Practical fit” while the ION Gaiter was simply pulled over the nose. 

 Table 3 – Physiological effects - Respiration rate, heart rate, blood oxygen

Test Subject	Face covering	Respiration/min.	Pulse/min.	Oxygen saturation
Male #1	No mask	7.6	63.9	96.9
Male #1	ION Gaiter	7.8	64.2	97.9
Male #1	N95	8.6	65.4	98.0
Male #2	No mask	7.2	64.8	98.9
Male #2	ION Gaiter	8.0	66.5	98.3
Male #2	N95	9.0	69.9	98.0
Male #3	No mask	10.0	63.5	95.8
Male #3	ION Gaiter	9.6	63.0	96.8
Male #3	N95	10.8	63.7	96.2
Female #1	No mask	9.0	57.1	99.0
Female #1	ION Gaiter	10.0	57.4	97.4
Female #1	N95	10.8	55.5	97.0
Female #2	No mask	6.4	59.1	98.8
Female #2	ION Gaiter	7.4	57.4	97.7
Female #2	N95	7.2	60.0	97.4

 

Breathability and filtration efficiencies of other face coverings

     Mask shortages during the COVID-19 outbreak resulted in make-your-own face coverings out of common woven fabrics in addition to designs from companies outside of the PPE industry. We tested more than 50 such surgical mask and gaiter designs not certified by the FDA or NIOSH that incorporate some fit modifications and appealing stylistic features.  Table 4 summarizes particle counting and pressure drop testing on a sampling of these devices representing the range of materials, designs and claimed filter efficiencies.

     Breathability, measured as pressure drop, was performed as previously described. All devices were tested with a “Perfect seal” (glued around the edges) and by “Practical fit” over the manikin.  The unregulated devices have similar construction with two layers of fabric and a middle pouch for insertion of disposable filters made from a non-woven matrix described as “nanofiber” or PM2.5. While the inclusion of a non-woven insert might seem a logical way to improve filtration efficiency, in practice the large pressure drops from the less breathable filter insert cause both inhaled and exhaled air to take the path of least resistance around the filtration matrix paradoxically causing poorer efficiencies. Devices D & E are commercial gaiter-like designs relying solely on size exclusion filtration. Promotional literature for these 2 devices claims bacterial filtrations of greater than 99% determined using the FDA BFE standard test protocol STP0004 specifying a glued seal over the testing apparatus.  “Practical fit” testing on the manikin gave much lower filtration efficiencies of 52% & 26.2%. 

 Table 4 – Breathability and particle filtering efficiency for uncertified masks

Filter device	Pressure drop (cm of water)	Filtration % for particles from 0.3 to ~10 microns
		Perfect seal	Practical fit on manikin
N95 3M 8210	-2.97	99.7	81.2
ION Gaiter	-0.43	98.3	99.6
A – Surgical mask 4 layers: activated carbon & PM2.5 filter inserts sandwiched between cotton/polyester fabric layers	-5.61	50.3	36.1
B – Surgical mask construction: non-woven filter insert sandwiched between 2 cotton layers	-8.79	56.4	35.6
C – Surgical mask construction:  activated carbon & non-woven filter inserts sandwiched between 2 cotton layers	-2.26	78.4	39.5
D – Gaiter-like design: non-woven “nano fiber” filter sandwiched between 2 layers of fabric	-2.24	98.5	52.0
E – Gaiter-like design: non-woven filter insert sandwiched between 2 cotton layers	-4.44	95.4	26.2
F – Conventional, disposable non-woven surgical mask	-2.84	97.9	31.3
G – Copper & zinc infused polyester-spandex “gaiter” with cotton-polyester filter insert	-2.34	31.3	11.1

 

Exfiltration of particles

     Table 5 compares exfiltration of particles for the surgical mask, N95 with and without 1-way out-flow valve, and the ION Gaiter.  Better exfiltration results were expected for the ION Gaiter due to favorable factors in its construction: 1) Tighter fit wrapping around the 360°degree circumferences of the neck and face, 2) Use of somewhat hydrophilic fabrics offering better adsorption of liquid aerosols compared to hydrophobic fibers in the N95, 3) Better breathability, 4) Larger filter surface area.  

 Table 5 – Particles escaping mask filtration after coughing

Device	0.3µ particles /15L	1-10µ particles /15L	% Filtered      at 0.3µ	% Filtered    at 1-10µ
No mask	23369	8322	NA	NA
Surgical mask	5413	1360	76.8	83.7
N95 mask with 1-way valve	2906	819	87.6	90.2
N95 mask without 1-way valve	3130	757	86.7	90.9
ION Gaiter	1607	455	93.1	94.5

                                

Discussion

      While vaccines and drug therapies are valuable tools to fight disease, many experts agree that highly effective FFD offer our best first-line defense. Fit is critical to FFD performance and under less-than-optimal fits the N95 performs significantly below 95% efficiency averaging around 80% in our studies.  A tight fit is difficult to achieve and maintain in actual use. Grinspun et al (2009)¹⁵ studied the two pathways for how particles evade filtration described as face seal leakage and penetration of the filter medium. They determined that ~90% of all unfiltered particles enter around the periphery with 10% penetrating the filter. They go on to conclude that improved filtration efficiency should focus on improving fit. Face size, shape, and facial hair compromise fit. Moving during task performance can further compromise seal. These factors together with comfort limitations previously discussed, result loss of fit or distaining use altogether.

     The COVID19 pandemic saw many new FFD offered for sale few of which have regulatory approval. Some of these devices feature activated carbon layers or fabrics treated with silver, copper and/or zinc with dubious claims or inferences as to the ability to kill virus and bacteria during the short transit times through the filter. Some of these new devices only provide filtration efficiency data collected using a “Perfect seal”.  Such claims can lead to a false sense of safety when they do not represent how the devices perform under actual use. The relevance of other standard test methods can also be questioned. For example, the test apparatus required for FDA bacterial filtration certification uses only a 40 cm² filter matrix surface area and a flow rate of 28.3 l/min far in excess of the normal breathing rates under typical working conditions. The effective ION gaiter surface area is 10 times greater than the N95. While current test methods may represent how N95’s function under perfect seal conditions, they do not objectively evaluate how non-traditional materials and designs function on human subjects.  

     A more relevant way to compare the filtration among various devices is to calculate performance based on what they fail to filter since it is particles evading filtration that concern health. Considering data in Table 2, the ION Gaiter allowed 0.5% bacterial penetration compared to 13.3% penetration for the N95 “Practical fit” and 76.6% for the surgical mask.  Using this method of analysis, the ION Gaiter reduces inhaled bacteria by 26.6-fold compared  the N95 and 153-fold reduction relative to surgical masks. Several studies have shown infection rates and disease severity are dose dependent.  It is reasonable to conclude that more efficient, easy-to-fit FFD capable of reducing the inhaled bioburden by orders of magnitude should lower transmission and severity in healthcare workers and the general public.

     Another feature to consider is reuse. ION Clairety products can be laundered retaining functionality over multiple washings. Conventional FFD specifies single-use disposability. This likely comes from a largely unproven presumption an FFD after being worn is a significant source of fomite transmission (disease transmission by touching the device). This assumption can be logically challenged. Disposable masks are donned and taken off essentially the same way as the ION Gaiter and Wrap to minimize contamination. The ease of fitting designs like the ION Gaiter should minimize touching required to achieve or maintain the fit. Disposable masks are discarded into a biohazard bag requiring storage until they can be incinerated or otherwise disposed off-site. Reusable devices go into a laundry bag to await a validated laundering/decontamination process identical to what medical facilities currently use for other reusable fabrics like surgical scrubs, sheets, towels etc. Devices validated for reuse could have prevented supply shortages of the N95 encountered during the pandemic.  Shortages paradoxically resulted in the unvalidated reuse and extended use of the N95. Cost considerations of the ION Gaiter and ION Wrap favor reusability. A device costing $10 and reusable over 100 launderings, when compared to a single-use N95 costing $1, would offer a 10-fold reduction in cost.   Laundering costs can be compared to disposal costs to see if there is further advantage. Considerations of environmental impact, sustainability, and use by the general public, favor reuse.  Fewer poorly biodegradable, plastic masks littering parking lots and filling dump sites should challenge conventions that PPE must be single-use and disposable.

    The alarming incidence of COVID-19 among first responders and healthcare workers indicates a need for better solutions. Improvements can be guided by performing more comprehensive and relevant testing methods similar to those discussed above. Our data demonstrates that non-traditional materials and principles of physics beyond mechanical filtration can be developed into designs providing superior filtration, ease-of-fit, breathability, and comfort. Those improvements could also improve FFD compliance by the general public and healthcare workers.

     The ION Gaiter and Wrap designs have been independently tested by an FDA licensed testing lab and found to exceed the “Level 2 (Higher Performance)” standards specified in ASTM-F3050. As such they are authorized by the FDA for “Emergency Use Authorization” for source control by the general public as well as by healthcare personnel in certain healthcare settings to help prevent the spread of infection or illness during the COVID-19 pandemic. The ION Gaiter and Wraps have not been cleared or approved by the FDA as medical devices.  Until such approval is obtained they must not be used in medical settings requiring the use of FDA approved devices. Despite our data and that of independent labs showing performance equal to or better than N95 and surgical masks, our devices cannot be used to replace those licensed devices. Certification and adoption of next-generation technology is not an easy task. It will require comprehensive verification of our data by other labs and careful review by regulatory agencies like the FDA and CDC (NIOSH).  New materials and designs will necessitate revision of test methods to better reflect performance in actual use as described above. Older regulations and methods should not hold back innovation or misrepresent actual performance in the field.  Comprehensive testing to generate relevant science-based data must replace established beliefs and assumptions.

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