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 maybe 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. There are similar laws around the world. Children under age 2 or those who cannot “medically tolerate” the mask are exempt in New York and other places.

In Kentucky, children who are 5 or younger and any person with a disability, or a physical or mental impairment, that prevents them from safely wearing a face covering are exempt. Rapidly changing personal protective equipment (PPE) mandates are resulting in compliance confusion and a mask shortage in many hospitals.

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.

N95 Masks

N95 Face Mask With Respirator Valve

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 comfortably 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. Medical care workers endure the discomfort to help patients.

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 breathing obstruction.

N95 masks may include at least one ventilator valve to exhale carbon dioxide. Those with exhalation valves should not be used in sterile conditions. Some doctors, wear a surgical mask and face shield over the valved N95 mask.

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
  • Nebulizers
  • Tracheostomy
  • Chest physiotherapy
  • Trach and airway suctioning
  • Bronchoalveolar lavage

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 mask 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

KN95 Mask With Respirator Valve

KN95 masks are basically N95 manufactured to Chinese regulations, with slight variation in particulate thresholds. During the initial N95 mask shortage, the U.S. Food and Drug Administration (FDA) delayed China’s large donation of KN95 masks destine 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.

FFP1–FFP3 Masks

FFP2 Face Mask With Respirator Valve

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 masks 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

P95 Elastomeric Respirator

3M Medium Thermoplastic Elastomer Series 5000 Half Mask Organic Vapor/Acid Gas Disposable Air Purifying Respirator pictured.

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, professional woodworkers or machinists.

B2 Mask

The B2 is a reusable respirator that filters 99% of common contaminants and reduces filter cost and waste by half. Unlike existing consumer masks, the B2 features a flexible, patent-pending facepiece.

Incubating from Kickstarter with $500,000 pledges, the B2 Mask price is north of $40 each including two disposable filters. It is designed to comply with NIOSH N99 standards per 42 CFR Part 84, but to date, the B2 Mask has not yet received regulatory approval 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

Surgical Masks

Disposable Surgical Mask

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 health care workers.

Head coverings and clear face shields are 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.

Inadequate Protection

Pitta Sponge Face Mask

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 has many wondering if this is a false sense of security for an aerosolized virus.

CDC Recommends DIY Bandana Face Mask

DIY Bandana Covering: In an unprecedented public service announcement, the CDC demonstrates how to make a DIY face covering with a bandana and rubber bands. According to the American Lung Association, using a homemade cloth face covering when near other people 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.

DIY Bandana Mask

You might wonder why the FDA has regulated standards for filtering 3 micron particulates among medical professionals while the CDC suggests the general population can make masks with bandanas and rubber bands. Even double-folded cotton fabric can block a significant amount of spittle discharged when speaking. Filtration is better with layers of different fabrics.

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.

Franziska Nordmann face mask scars

Franziska Nordmann shows scars from prolonged work shift wearing PPE. Many health care personnel work longer than usual to help coronavirus patients.

DIY Cotton Mask: Masks with just one layer of permeable fabric or those that expose the nose are ineffective in protecting against airborne viruses. A polyester or silk scarf without insulation is largely decorative. If light easily passes through the fibers, virus particles can pass through. Individuals 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 or wear a surgical mask over a respirator mask.

John Henao face mask bag

John Henao wears plastic bag taped around his neck over surgical mask. With short supplies, some health care personnel fashion unorthodox protection.

Proper Mask Doffing

Viruses don’t just bounce off of masks. They get trapped on the surface. 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 have stretched out and no longer cover your nose and mouth, have 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. Unless you are wearing a mask to constrain a virus you yourself have, the exposed outer layer is the most virus-prone surface. (If you carry the virus, the internal surface is most infectious.)

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 before and after touching any part of PPE. Learn about donning doffing masks on YouTube.

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.

Recycle gloves and discard optional filter. (It is preferable to store used gloves free of biohazardous wastes in a separate container for recycling.) Then thoroughly wash face and hands immediately.

Valve Controversy

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.

Pocket mask filtration

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.

During warm summer months, wearing a mask can get warm and uncomfortable as it traps heat. If you are struggling to breathe, remove your mask. Make sure you remain at least six feet away from others people. Sit in the shade and drink some water to prevent heat stroke.

Safety Glasses

Safety Glasses

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/Class (Standard)N95 (NIOSH-42C FR84)KN95 (GB2626-20 06)FFP2 (EN 149-2001)
Filter perfor­mance ≥X% efficient≥95%≥95%≥94%
Test agentNaClNaClNaCl and paraf­fin oil
Flow rate85 L/min85 L/min95 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 rate85 L/min85 L/minVaried – see above
Exhale resistance – max pressure drop≥245 Pa≥250 Pa≥300 Pa
Flow rate85 L/min85 L/min160 L/min
Exhale valve leakage require­mentLeak rate ≥30 mL/minDepres­sur­ize to 0 Pa ≥20 secN/A
Force applied-245 Pa-1180 PaN/A
CO2 clearance require­mentN/A≤1%≤1%

Pa – Protactinium (radioactive metal); NaCl – Sodium chloride (salt). Total inward leakage (TIL) – Amount of a specific aerosol that enters tested respirator facepiece via both filter penetration and faceseal leakage, while a wearer performs a series of exercises in a test chamber.

Based on this comparison, it is reasonable to consider US NIOSH N95, China KN95 and European FFP2 respirators as “equivalent” for filtering non-oil-based particles such as those resulting from wildfires, PM 2.5 air pollution, volcanic eruptions, or bioaerosols (e.g. viruses). Source: 3M


Face Masks That Provide Best Virus Protection

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 offer good protection against smog, dust, and viruses. A removable filter allows you to adjust for optimum protection and comfort. Safety eyewear is also available for personal public use. #MaskUp

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Updated: Sep 20, 2023

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