FAQs on N95 Masks

A guide to understanding the N95 Masks

-By Dr. Shruti Maroo Rathi

HOME | COVID-19 & DENTISTRY | FAQs on N95 Masks

When dentists return to their clinics in a changed post-coronavirus world, it is essential for them to understand the protection offered by the various masks and respirators available in the market.


2.What does N95 Stand for?

3.What is the difference between KN95, N95 and FFP2/P3?

4.How to identify counterfeit N95 Masks?

5.What are the Steps in Proper Donning and Doffing of respirators?

6.How to Check the seal of N95 Masks?

7.Respirator Re-Use – How to sanitize them safely?

1.    Surgical Masks Vs N95 Respirators

Surgical masks are a 3-ply (three layer) masks, with a “melt-blown” layer sandwiched between two sheets of “non-woven” fabric. This melt-blown layer possesses the filtering capability and is made up of polypropylene non-woven fabric. The filtration level of a mask depends on the quality of fiber in the melt brown layer, the way it’s manufactured, its web’s structure, and the cross-sectional shape.

These surgical masks are designed to capture bodily fluid leaving the wearer and therefore provides only one-way protection. For eg; it is worn during surgery to prevent coughing or sneezing, on the patient and not for the protection of the doctor. An obvious shortcoming of the surgical masks compared to respirators is their lack of a tight face fit, which leaves gaps around the edges.

Respirators are tight fitting devices designed to create a facial seal to protect the wearer. The filtration material present on the mask is made up of an electrostatic non-woven polypropylene fiber. Some of the respirators have a little plastic valve embedded in the fabric. This valve closes when the wearer breathes in and so pathogens can’t get in through it. But it opens while breathing out, making it easier to exhale the air. It also lessens the moisture build-up inside the respirator. The drawback of valved respirators is that they do not filter the exhalation air. This one-way protection may put others around the wearer at risk, especially in a situation like COVID-19. It’s for this reason that hospitals and other medical practices DO NOT use the valved respirators.

One of the most commonly discussed types of respirator is N95.

2. What does N95 Stand for?

N: N stands for Not resistant to Oil, meaning that this mask can be used if no oil-based particulates are present. Other masks ratings are R (Resistant to oil for < 8 hours) and P (oil Proof or Strongly Resistant to oil)

95: 95% efficiency to filter out contaminants like dusts, mists and fumes of size greater than .3 microns. Masks with 99 rating have a 99 % efficiency and masks ending in 100 are 99.97 percent efficient which is same as a HEPA quality filter.

3. What is the difference between KN95, N95 and FFP2/P3 masks?[1]

These are different standards for masks. KN95 are Chinese standards whereas N95/99 is an American standard managed by NIOSH. European countries have 2 different standards. Filtering Face Piece (FFP1/2) or P1/2/3, both are managed by CEN (European Committee for Standardization).

Let’s compare the filtration capacity of these masks:

Respirator StandardFilter Capacity (defined as percentage of  particles filtered that are 0.3 microns in diameter or larger)
FFP1 /P1At least 80%
FFP2 /P2At least 94%
P3At least 99.95%
N95At least 95%
N99 & FFP3At least 99%
N100At least 99.97%
KN95At least 95%

4. How to identify counterfeit N95 Mask?[2]

Counterfeit respirators are products that are falsely marketed and sold as being NIOSH-approved and may not be capable of providing appropriate respiratory protection to workers.

Signs that a respirator may be counterfeit:

  • Absence of or misspelled NIOSH in the markings
  • Lack of approval (TC) number on N95 or headband
  • Presence of decorative fabric or add-ons (e.g., sequins)
  • Claims approval for children use (NIOSH does not approve any type of respiratory protection for children)
  • Presence of ear loops instead of headbands

Third Party Marketplace red flags:

  • Use of terms like “legitimate” and “Genuine”
  • Customer Feedback that seems suspicious
  • Inconsistency in the type of products sold
  • Prices too good to be true, and
  • Claiming “Unlimited Stock” during the times of shortage

Website Tip Off:

  • Primary Email contact uses a free email service
  • Presence of typos, bad grammar and other errors
  • Contains broken links
  • Site is unfinished and temporary dummy text is still present

5. Steps in Proper Donning and Doffing of N95 Mask:

Donning of respirators[3]

Image Source

  1. Cup the respirator in hand such that the nosepiece is at the fingertips, allowing the straps to hang freely below hand.
  2. The respirator is positioned under the chin with the nosepiece up.
  3. While holding the respirator in place, the top strap should be pulled over the head so it rests high on the back of the head. Holding the respirator firmly in place, the bottom strap is also pulled over the head and is positioned around the neck, below ears. The straps are untwisted.
  4. Both hands’ fingertips should be used to mold the nose clip against the nose and face. It should not be pinched with one hand.
  5. User should seal check every time the respirator is put on and it should be done before entering a patient room.
  6. Respirators are to be discarded when it gets damaged, dirty or breathing through it becomes difficult.
  7. He front of the respirator should NOT be touched as it may be contaminated.
  8. Keep the respirator clean and dry.

Doffing of the respirator

Image Source: 3M

  1. Without touching the respirator, the bottom strap is slowly lifted from around the neck and over the head.
  2. The top strap is then lifted off. The outside of the respirator should not be touched at any point as it may be contaminated with the virus.
  3. The used respirator should be stored or discarded according to the infection control policy.

6. How to Check seal of the N95 Masks?[4]

To perform the user seal check, both hands are placed completely over the respirator and the air is exhaled sharply. If air leaks around the nose, then the respirator is to be adjusted at the nose piece as described in step 4. If air is leaks at respirator edges, straps are adjusted along the sides of the head. Seal check is performed again, if any adjustments are made. If a proper fit is not achieved then, try a different variety.

Facial hair will cause the respirator to leak, so users should be clean-shaven. Some types of facial hair are acceptable as long as the facial hair does not lie along the sealing area of the respirator. (Click to view the acceptable facial hairstyles for workers who wear N95 Masks)

7. Respirator Re-Use – How to sanitize them safely?[5]

If respiratory protection must be used, and acceptable alternatives are not available, the National Institute for Occupational Safety and Health has identified available research that suggests the following methods offer the most promise for decontaminating FFRs:

  • Vaporous hydrogen peroxide;
  • Ultraviolet germicidal irradiation; and/or
  • Moist heat (i.e., using an oven).
  • If the methods above are not available, microwave-generated steam or liquid hydrogen peroxide would also be suitable.

For More details on reuse of the masks refer to the following article:

[1] N95 vs FFP3 & FFP2 masks – what’s the difference? https://fastlifehacks.com/n95-vs-ffp/

[2] https://www.cdc.gov/niosh/npptl/usernotices/counterfeitResp.html

[3] Proper N95 Respirator Use for Respiratory Protection Preparedness: https://blogs.cdc.gov/niosh-science-blog/2020/03/16/n95-preparedness/

[4] Helping you wera it right by 3M:  https://multimedia.3m.com/mws/media/887642O/wear-it-right-auratm-respirator-1870-poster-english.pdf

[5] Decontamination and Reuse of Filtering Facepiece Respirators: https://www.cdc.gov/coronavirus/2019-ncov/hcp/ppe-strategy/decontamination-reuse-respirators.html

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