Does it matter what type of face mask you use?

SARS-CoV2, the coronavirus that causes COVID-19, is an airborne disease. This means that it is mostly transmitted by tiny droplets that are exhaled and can float in the air over longer distances. A good mask blocks those droplets and is an important part of public health protocols to contain the virus, along with hand hygiene and social distancing. The data shows that wearing any mask compared to no mask reduces infection risk by around 70 percent. In settings with a moderate to high risk of infection, wearing the N95 type respirator mask further reduced the risk of infection by roughly half as compared to surgical masks.

Why have mask recommendations changed?

Early in the pandemic, these types of masks were in short supply which led officials to discourage their use by the general public. Now supplies are more available, and we have better data on the superiority of N95 masks over surgical or cloth masks.

Mask recommendations have changed to reflect the level of protection recommended against variants. The omicron variant is at least 3 times more contagious than the already contagious delta variant, and the new BA.2 subvariant of omicron may be even 1.5x more contagious than the original omicron. While these may seem like small numerical differences, they have major impacts on viral exposure.

What is the difference between N95, KN95, KF94, and other masks currently available?

These terms are the names for the testing protocols of governmental agencies and refer to the standards for capturing more than 95 percent (or 94 percent, respectively) of aerosol particles. N95 is the U.S. standard certified by NIOSH (National Institute for Occupational Safety & Health, a research agency under the CDC). The KN95 is the Chinese standard and KF94 the Korean standard. There is also the European FFE2 standard. The differences between these mask types are minor for most consumers. In fact, they are considered equivalent because the testing protocols are very similar.

How do N95-respirator type masks work?

Respirator masks, such as N95 and equivalent, are made from high-tech material – they are not merely filters that sift out particles by size. They are dense meshes of special fibers that actively trap aerosol particles due to carefully designed microarchitecture that slows airflow and electrostatically attracts the aerosols. While such materials do not just “saturate” (like a filter), their ability to capture droplets decreases over time. They should be replaced after 20-30 total hours of use or after 5–7 uses. Don’t wash them!

How can you tell if an N95 mask is authentic or fake?

It has been estimated that 60 percent of the N95 respirator masks are fake. Producers of counterfeit masks sell their product under another name and misleadingly mention NIOSH on the package, present a fake stamp of approval by NIOSH, including its TC number, or more boldly, forge an entire brand name product that is NIOSH approved.

It is possible to identify misleading or false claims of NIOSH approval. Dr. Huang recommends using these steps to identify fake N95 and equivalent masks:

1. Positive identification of approval by the CDC’s NIOSH

Look for the TC number of specific brands that NISOH has certified, using the list of products provided by NIOSH here.

2. Negative identification

NIOSH also explicitly lists (by years) the companies that falsely claim to have NIOSH approval on N95s – a useful list with images of the fakes. But there are also lists of well-known brands collected by public media. Such lists also name manufacturers that do not even claim to be N95 or NIOSH-certified but hide behind serious-looking packaging – especially in the case of KN95 masks. Note that the CDC only lists manufacturers that misuse the trademarked NIOSH/N95 label. While KN95 masks are considered equivalent, the CDC does not intercept KN95 mask manufacturers that cheat.

3. The smell test

Some products try to look official, but the ignorance of the bogus manufacturers can be a giveaway. For example, some masks claim to be FDA approved when the FDA does not approve or certify face masks.

The data is clear that wearing any mask is better than no mask but wearing an N95-respirator correctly may provide you with extra protection against exposure.  

Additional resources:

• For additional information on alternative masks for special situations, considerations for children, or more mask information, check out the CDC website.
• Consumers can pick up a free N95 mask at many pharmacy locations. The Strategic National Stockpile has distributed N95 respirators to pharmacies throughout the country.
• For information about how to use your N95 correctly, read this guide from the CDC.

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