How to Tell if an N95 Respirator Mask Is Effective

 8 tips for evaluating respirator face masks

There is currently a shortage of PPE in the world due to the coronavirus pandemic, and prices for protective face masks (also known as respiratory masks) are skyrocketing. As more and more sellers emerge on the internet, it might be difficult to differentiate between masks that truly work in protecting you from viruses and masks that don't.

With these following 8 tips, you can evaluate protective respirator face masks to see if they are fit for the purpose of preventing airborne particles, such as viruses, bacteria or dust.

Face Mask Evaluation Criteria

1. Choose a mask that is rated at least FFP2, N95 or KN95

Authorities around the world use different names for qualifying respiratory masks.

The European Norm Directive (EN149:2001) divides protective respiratory masks into 3 classes: FFP1, FFP2 and FFP3.

  • FFP1: Filters at least 80% of airborne particles.
  • FFP2: Filters at least 94% of airborne particles.
  • FFP3: Filters at least 97% of airborne particles.

For the best protection, we recommend using FFP2 quality masks or above.

The US National Institute of Occupational Safety and Health (NIOSH) states that for N95 series masks, the mask must filter at least 95% of airborne particles. KN95 format masks adhere to GB2626-2006 and offer the same level of protection as N95 (Filtration efficiency ≥ 95%).

Another popular mask is the Surgical Grade Face Mask. These are traditionally worn by medical professionals when carrying out procedures in order to catch microorganisms shed in liquid droplets and aerosols from the wearer's mouth and nose. Their main purpose is therefore to protect those in the wearer’s surroundings as opposed to the actual wearer.

As a result of the recent COVID-19 pandemic, a lot of people and businesses are making their own masks out of cloth and other fabrics. In situations where it might be difficult to maintain social distancing measures it is definitely better to wear a cloth mask than nothing as it will help to prevent the wearer from potentially spreading the virus to others. We would strongly recommend a Surgical Grade mask over a cloth mask, and above all, an FFP2 quality mask or above.

In summary: FFP2, N95 or KN95 face masks offer a very similar level of protection. Choose either of these formats when buying a facemask for protection against viruses.

Face Masks Compared

Cloth Mask Surgical Grade KN95/FFP2 (N95 equiv.) N95 Respirator
No fit test required Requirement
Comfortable to wear Can be uncomfortable due to the hardness and tight fitting
Protects others from wearer
Protects wearer from others Limited Limited
Adjustable metal nose bridge No (Typically)
Concealed nose bridge No (Typically) No (External)
Application method Ties or elasticated ear loops Elasticated ear loops Elasticated ear loops Drawstrings/Elasticated straps
Leakage Occurs around edges Occurs around edges Minimal Minimal
Can use more than once* ✔ (Can be washed) Single use only
Design and fit Flat design & loose fit Flat design & loose fit Contoured design and snug fit Hard, dome-shaped shell and tight fitting
Number of layers Varies: a high quality cloth mask has at least 3. 3-ply layers 6-ply layers 4+ply layers
Filtration efficiency Does NOT provide the wearer with a reliable level of protection from inhaling smaller airborne particles. Does NOT provide the wearer with a reliable level of protection from inhaling smaller airborne particles ≥95% ≥95%

all are technically single use products however the KN95, FFP2 and N95 masks can be reused in certain circumstances and cloth masks can be washed easily.

2. Choose a face mask that fits snugly

We have found that 3D foldable, pyramid-shaped face masks offer a close fit to all facial shapes and sizes and are very ergonomic due to the nature of the fabric used. This format works well for face masks rated with FFP1, FFP2 or FFP3.

Traditional respirator face masks with a hard, dome-shaped shell (also known as a cup mask) do not fit universally and require a fit test for different face shapes. 

Whilst both mask types filter out the same number of particles, we have found that harder shell masks can leave gaps around the edges and that’s why they require an initial respirator fit test to identify the right model, style, and size respirator for each person. On the other hand, the 3D foldable pyramid-shaped masks work better straight out of the box in that they fit snugly due to the flexible nature of the fabric used.

In summary: We recommend 3D foldable, pyramid-shaped face masks.

3. Choose a face mask that’s easy to put on and take off

Face masks come with either:
(1) elasticated ear loops,
(2) drawstrings that require tying around the back of the head, or
(3) elasticated straps which go around the entire head.

We found that option (1), elasticated ear loops, offers the fastest way to put a mask on or take it off. They are also the most comfortable. Face masks with (2) drawstrings or (3) straps that go around the head can be more uncomfortable when worn over a longer period, as they need to be pulled tighter to prevent movement of the mask. They can also be difficult to put on, especially if the user has longer hair.

In summary: For the best ease of use, we recommend masks with elasticated ear loops.

4. Choose a face mask with a nose bridge

Many respirator masks often have a nose bridge or nose piece that helps the mask stay in the right place, increasing the quality of the fit and protection. This can also help those who wear glasses to avoid fogging.  We found that the masks that have a concealed nose bridge are more comfortable than masks with a nose bridge that is not stitched inside the mask, as the metal makes contact with the user's skin.

In summary: For the best fit and comfort, choose a mask with a concealed, stitched-in nose bridge.

5. Check what materials the mask is made of

The key filtration material inside an FFP2 or N95 mask should be melt-blown nonwoven polypropylene fabric. This is the key material that acts as a filter for air particulates, and it is waterproof and burn proof.

The best masks have two layers of this material, and they work together to prevent airborne infection from droplets or aerosol-sized particles associated with viruses. Respirator masks should also have two layers that separate the filtration layers.

There is a quick test you can do on the inner layer to see if it is the real thing. This is not an infallible test but it can work to quickly identify if your product is genuine. You can do this by cutting the mask to give a cross-section of the layers. The polypropylene fabric layer should be both waterproof and flame-retardant. If the material leaks or burns, it is most likely not the genuine melt-blown nonwoven polypropylene.

If using the product inside the EU, the product should be CE-marked in accordance with the requirements of Regulation (EU) 2016/425, which concerns the manufacture of personal protective equipment.

Furthermore, we suggest using a mask that allows adequate breathability. We have found that materials with a respiratory resistance of <80pa give a good result in terms of breathability.

In summary: Choose a mask made with the correct materials.

6. Choose a mask that has a comfortable inner layer

Most standard FFP2 or N95 quality masks come with four layers, whilst some masks have five layers. The ability of the mask to prevent air particles, such as viruses or droplets, depends on the rating of the mask (i.e. FFP2 or N95), but also the types of material and layers used. A fifth layer can improve comfort whilst not necessarily improving mask rating.

We found that masks with five or more layers that have a soft, skin-friendly inner layer offer more comfort when used, which greatly improves the wearability of the mask over a longer period of time. 

In summary: If possible, choose a mask with 5 or more layers.

7. Consider exhalation valves

Vented (or valved) masks can offer better comfort, as the one-way exhalation valve allows your breath to exit without condensing inside the mask or fogging your glasses. The vent does not make the mask a better or worse filter in principle, although we could not find tests directly comparing vented and non-vented. 

The main concern we have with vented masks is that a sick person could vent out air containing an infection, without any filtering, and thus reduce the mask's ability to limit the spread of an airborne virus. We think a mask should not only stop a person becoming infected but also prevent a person infecting others, especially when they may not know they are infected (as can happen with COVID-19).

In summary: It is a personal choice, but we prefer non-vented masks over vented.

8. Find a face mask seller that is an established, trusted business

With the rapid increase in face mask sellers, we advise choosing a reputable, locally based manufacturer or wholesaler to ensure that the:
(1) quality and mask rating is accurate,
(2) speed of delivery is acceptable,
(3) traceability can be done,
(4) accountability can be had in the event of missed deliveries or other issues, and
(5) fair pricing can be secured,
(6) when supplied singly, they should be individually packed, allowing the masks to be protected and kept hygienic before use.


  • It’s good to hear that this post was helpful to you, Helen! If you have any questions, don’t hesitate to get in touch with us at

    Robert (Mod)
  • I found this post whilst searching for information on face masks as I need to purchase them for my workplace and I found the table comparing the different masks especially helpful.


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