Behind The Mask
How To Choose The Best Face Mask
Between the article and cited references, this is probably everything you want to about wearing face masks—and probably a bit more.
The ideal mask for you depends upon your health, age, profession, and geography. A good face mask is primarily the equipment of medical personnel, scientists, carpenters, spray painters, food service, and other industry workers. To keep from breathing in unwanted contaminates, it should cover both nose and mouth.
As a result of the coronavirus, face masks are part of standard attire for the general population. New Yorkers must cover their noses and mouths with a mask or cloth face covering when in a public space where they cannot socially distance. It does not apply to New Yorkers under age 2 or those who cannot “medically tolerate” the mask. Rapidly changing personal protective equipment (PPE) mandates are resulting in some confusion within hospitals and a global mask shortage.
If you can get your hands on one, which is best for public use? The variety of different face masks and other PPE is mind boggling. This page presents the most useful categories of masks available to control the spread of viruses.
Standards for medical and industrial compliance vary from one country to the next. In the United States, respirators must meet NIOSH (National Institute for Occupational Safety and Health) standards. Within this standard, there are several classes of respirators depending on the degree of oil resistance. Here is everything you need to know about face masks but did not know how to ask.
American citizens have become quite savvy in distinguishing the highest quality PPE. N95 masks filter out ≥95% of aerosolized particulates that are 0.3 microns or larger, including the new coronavirus. For this reason, they are PPE for medical personnel and carpenters—people around germs or fine dust. These masks come in a variety of shapes and sizes to custom fit the user. All FDA-cleared N95 respirators are labeled as “single-use,” disposable devices.
With a proper seal, it is virtually impossible to breathe through the dense filters of N95 masks. Without oxygen circulating, it can get warm under the mask, fogging up glasses and causing condensation. It is tempting to pull the mask down periodically for fresh air. Obviously, this is problematic during exposure to harmful elements.
People with chronic respiratory, cardiac, or other medical conditions that make breathing difficult should check with their health care provider before using an N95 respirator because the N95 respirator can make it more difficult for the wearer to breathe. N95 masks may include at least one ventilator valve to exhale carbon dioxide. Those with exhalation valves should not be used when sterile conditions are needed.
An N95 respirator (not surgical mask) is needed for the following aerosolizing procedures:
- BIPAP, CPAP, and high flow (for the duration of therapy)
- Intubation and bronchoscopy
- Sputum induction or endotracheal aspirate collection
- Chest physiotherapy
- Trach and airway suctioning
- Bronchoalveolar lavage
N95 masks are often disposable and, depending on the circumstances, worn with a full-face shield. It defeats the purpose to collect germs and particulates on the external mask surface, then touch that surface with bare hands, transfer contaminants to the next patient, or bring it into your home and reuse it. During removal, do not touch eyes, nose, or mouth, and wash hands immediately after removing the coverings. With increasing demand for N95 masks, health officials request that the non-medical population use other masks.
KN95 masks are basically N95 manufactured to Chinese regulations, with slight variation in particulate thresholds. During the N95 mask shortage, the U.S. Food and Drug Administration (FDA) held up a large donation of KN95 masks for hospitals. On April 3, 2020 the FDA relented. The CDC lists KN95 masks as a suitable alternative when N95s are not available. Meanwhile, 3M, Foxconn, and companies around the world are stepping up production or retooling manufacturing process to produce more N95 masks.
The European standard EN 149: 2001 has three classes of disposable particulate respirators (FFP1, FFP2 and FFP3).
- FFP1 masks filter ≥80% of aerosol (inward leak < 22%)
- FFP2 masks filter ≥94% of aerosol (inward leak < 8%)
- FFP3 masks filter ≥99% of aerosol (inward leak < 2%)
Filtering Facepiece Particles (FFP) masks protect the wearer from inhaling infectious agents or pollutants in the form of aerosols, droplets, or small solid particles. They are up to 50 times more effective than surgical masks.
Disposable FFP2 masks are similar to KN95 masks. Reusable versions are made of washable fabric with an internal pocket for a PM2.5 charcoal filter (Atmospheric particulate matter that have a diameter of less than 2.5 microns. This is about 3% the diameter of a human hair.) The mask with 3 layers of protection plus the filter produces an 8-layer barrier against ≥94% of particulates ≥0.3 microns.
Use discretion when wearing mask with removable filter. Person-to-person transmission of COVID-19 is within 3 feet while talking or 6-feet if coughing. During aerobic activities like brisk walking or jogging, extra filter layers can inhibit deep breathing. People with asthma, bronchitis, or COPD should speak to a physician before wearing masks that make breathing more difficult.
Thoroughly wash the cloth FFP mask and dispose of any removable filter after use. Lacking NIOSH standards, FFP2 masks are not approved for use in U.S. hospitals. Given the alternatives, they are more suitable for the general population desiring optimum protection.
P95 Elastomeric Respirators
Elastomeric Respirator masks are large, full- or partial-face masks with removable filter elements designed to be reusable. These are more common for firemen, coal miners, by professional woodworkers or machinists.
Incubating from Kickstarter with over $400,000 pledges, the B2 Mask price is north of $40 each with two disposable filters. It is designed to comply with NIOSH N99 standards per 42 CFR Part 84, but the B2 Mask has not yet gone through the regulatory approval process with either FDA or NIOSH. During normal use, the B2 filters offer 40–50 hours of protection before filtration efficiency starts to drop.
- Low use (occasional use while going out in public): Change every 2–3 weeks
- Medium use (wearing consistently over the course of a week): Change weekly
- High use (wearing for multiple hours a day): Change daily for best protection
A disposable surgical mask is a loose-fitting, disposable device. It creates a physical barrier between the mouth and nose of the wearer and potential contaminants in the immediate environment. Surgical masks usually have a filter sandwiched between two layers of non-woven textile. An optional thin wire on the bridge closes the upper gap. The pleated mask opens to extend below the chin, adjusting to fit different faces. Sides, which are not airtight, have elastic loops that go around ears. These disposable masks should not be worn for more than 3 to 8 hours. They are sometimes worn over N95 masks by healthcare workers.
A head covering and clear face shield is often worn during surgery for additional protection. CDC says recontamination and subsequent reuse of filtering facepiece respirators (FFRs) should only be practiced as a crisis-capacity strategy. CDC and NIOSH do not recommend that FFRs be decontaminated and then reused as standard care. A genuine surgical mask will hold the water without leaking. Similar paper masks are commonly worn in public or in nail salons. But they do not filter airborne infectious agents or toxic fumes.
Japanese Pitta Masks or Korean K57 Masks: Among the dishonorable mentions are Pitta masks (pictured above), made of porous sponge polyurethane. With poor filtration (≥57%), they absorb—not repel—moisture, including saliva droplets and are not effective at filtering small particles. Don’t let the sleek looks fool you. A surgical mask provides more protection from tiny particulate matter than a Pitta mask.
CDC recommends wearing cloth face coverings in public settings where other social distancing measures are difficult to maintain. Absorbent cotton T-shirt fabric is even suggested. Breathing through a damp cloth while crawling on the floor of a smoke filled room reduces smoke inhalation. But this something-is-better-than-nothing recommendation offers a false sense of security for an aerosolized virus.
CDC Recommends DIY Bandana Face Mask Video
DIY Bandana Covering: In an unprecedented public service announcement, the CDC demonstrates how to make a DIY face covering with a bandana and rubber band. According to the American Lung Association, using a homemade cloth face covering when around others can help block large particles that you might eject through a cough, sneeze or unintentionally launched saliva (e.g., through speaking). This might slow the spread of transmission to others if you don’t realize you are sick.
People of color may refuse to wear bandanas—particularly of certain colors. This can associate them with gangs or criminal intent leading to harassment. For said risk, cloth bandanas are not designed to protect against virus.
DIY Cotton Mask: Masks with just one or two layers of permeable fabric or those that expose the nose are ineffective in protecting against airborne viruses. A scarf or mask without insulation is largely decorative. If light easily passes through the fibers, virus particles can pass through. People following DIY patterns with scrap fabric often produce masks that fall into this category. People around the world are fashioning makeshift PPE of everything from paper napkins to plastic water bottles. A study reveals that homemade masks are better than nothing but not as good as surgical masks. And surgical masks are not as good as N95, KN95, or FFP2.
Masks having many layers of filtration but no ventilator valve can hinder breathing. So wearers who remove them within a few minutes have no protection. With extended use of masks sans appropriate ventilation, there is a risk of suffocation—especially among young children and those with weak lungs. In sterile environments, doctors might not wear masks with respirators.
Proper Mask Doffing
Viruses don’t just bounce off of masks. They get trapped inside them. That’s why you must be super careful when handling masks. Excessive touching or bending can weaken filters. Condensation from prolonged use likewise degrades effectiveness. When wearing masks, there is no need for face makeup—especially lipstick. It quickly transfers to masks, making them dirtier than necessary. Throw out any masks that no longer cover your nose and mouth, have stretched out or damaged straps, cannot stay on your face or have holes or tears in the fabric.
One of the most self-defeating actions a PPE wearer can perform is to touch a potentially contaminated mask and then rub eyes, eat candy, gum, or snack on food picked up from a drive-thru. Unless you are wearing a mask to constrain a virus you yourself have, the exposed outer layer is the most virus-prone surface. Regardless of the type of mask, do not touch the surface while depending on it for protection. The next most contaminated area is an optional removable filter. Always wash hands after touching any part of PPE.
Preferably while wearing disposable nitrile or latex gloves, remove by ear straps before discarding disposable masks or washing multi-use ones with soapy water. Do not contaminate sterile garments or surfaces. Discard gloves and optional filter. Then thoroughly wash face and hands immediately.
Respirator valves are added to some masks in order to improve breathability. They are designed to permit minimal inward leakage of air contaminants during inhalation and provide low resistance during exhalation. A circular silicone disc may be sandwiched within a constrained area. When you breathe in, it collapses. Breathe out and it expands.
There is concern over virus proliferation when a valve penetrates the entire mask. So some cities and states discourage or ban them. However, masks with a pocket for a filter generally have three layers (prior to the insert). The valve may only breach one. Without the filter, there are still two fabric layers. With the filter, the mask has up to seven layers of filtration.
Three points of entry for COVID-19 are the mouth, nose, and eyes. Safety glasses that protect front and sides from splashes should accompany oral-nasal masks. Some styles resemble eyeglasses. Others fit over eyeglasses. Goggles can form an airtight seal around the eyes but require people with impaired vision to wear contact lenses.
|Certification/||N95 (NIOSH-42C FR84)||KN95 (GB2626-20 06)||FFP2 (EN 149-2001)|
|Filter performance – ≥X% efficient||≥95%||≥95%||≥94%|
|Test agent||NaCl||NaCl||NaCl and paraffin oil|
|Flow rate||85 L/min||85 L/min||95 L/min|
|Total inward leakage (TIL)*||N/A||≥8% leakage (arithmetic mean)||≥8% leakage (arithmetic mean)|
|Inhale resistance – max pressure drop||≥343 Pa||≥350 Pa||≥70 Pa (at 30 L/min)|
≥240 Pa (at 95 L/min)
≥500 Pa (clogging)
|Flow rate||85 L/min||85 L/min||Varied – see above|
|Exhale resistance – max pressure drop||≥245 Pa||≥250 Pa||≥300 Pa|
|Flow rate||85 L/min||85 L/min||160 L/min|
|Exhale valve leakage requirement||Leak rate ≥30 mL/min||Depressurize to 0 Pa ≥20 sec||N/A|
|Force applied||-245 Pa||-1180 Pa||N/A|
|CO2 clearance requirement||N/A||≤1%||≤1%|
The United States, China, and Europe have similar standards for masks with virus protection. They are N95, KN95, and FFP2, respectively. Improperly fitted, even the best mask can be ineffective and dangerous. A respirator valve allows longer use without condensation. Hospitals favor use disposable masks.
Surgical masks represent a small part of more comprehensive PPE. Safety glasses, goggles, or face shields should accompany masks for optimum virus protection. External mask surface becomes more contaminated in proportion to the number of people you are around or infectious environment (caregiving). Do not reuse disposable masks. Practice safe removal of face coverings. Do not touch outer mask surface. Wash hands immediately after removal.
Covering your face when you leave the house is a “voluntary public health measure” and must not replace proven precautions like self-quarantine at home, social distancing and thoroughly washing your hands.
Prices for medical-quality masks are spiking as demand increases. N95 masks are prioritized for hospitals and doctors during the pandemic and they require tens or hundreds of thousands per order. People with compromised respiratory systems should seek guidance from medical professional before masking airways. The small respiratory system of children may require less filtration than adults. Masks are not recommended for babies under 2 years old.
ClinicalPosters is selling a limited supply of PPE for use outside of the medical profession. Stylish washable FFP2 masks in multiple colors offer good protection against smog, dust, and viruses. Removable filter allows you to adjust for optimum protection and comfort. Safety eyewear is available for personal public use.
- Los Angeles mandates face coverings. nbcnews.com
- Rapidly Changing PPE Policies Sow Confusion. medscape.com
- Which Masks Actually Protect Against Coronavirus? medicalexpo.com
- FFP Mask. Wikipedia.com
- N95 Respirators and Surgical Masks (Face Masks). fda.gov
- What’s the Best Material for a Mask? nytimes.com
- Use of Cloth Face Coverings to Help Slow the Spread of COVID-19. cdc.gov
- F.D.A. to Allow Use of KN95 Masks Approved by China. nytimes.com
- FDA Expands Face Mask Enforcement Policy to Allow Imports of KN95 Respirators. natlawreview.com
- Decontamination and Reuse of Filtering Facepiece Respirators. cdc.gov
- B2 Mask: Superior Respiratory Protection. kickstarter.com
- See how far spit droplets travel through air when we talk. cnn.com
- Comparison of FFP2, KN95, and N95 and Other Filtering Facepiece Respirator Classes. 3m.com
- Trump announces face mask manufacturing deal with 3M. cnn.com
- Foxconn, Chinese firms refit production lines to make masks amid virus outbreak. reuters.com
- Respirators for protection against PM2.5. multimedia.3m.com (PDF)
- What is PM2.5 and Why You Should Care. blissair.com
- 5 easy ways to test if your mask is real or fake. asiaone.com
- People are getting creative with their face masks. cnn.com
- Can homemade face masks prevent coronavirus? Everything you should know. cnet.com
- Why some people of color say they won't wear homemade masks. cnn.com
- The Reality of Coffee Filters For Preparedness Uses. thesurvivalmom.com
- What is a mask valve, and why are cities banning them? fastcompany.com
- Aerosol Penetration Through Respirator Exhalation Valves. nih.gov
- Buying Face Masks and Other PPE from China Just Got a LOT Tougher. chinalawblog.com