Why I Wear the Same KF94 Mask for Weeks

(And Maybe You Should Too)

Disclaimer: The views expressed are my personal opinions and not meant to be medical advice.

Main Takeaways

• KF94 (Korean) or KN95 (Chinese) certified face masks provide significantly more protection (>90%) than simple cloth or loosely worn surgical masks (<50%). FFP2 (European) face masks also offer a similar standard.

• The filtration efficiency only lowers 2-3% from extended use (~40 hours) of the same KF/KN mask in an average environment.

• It’s reasonably safe. Contracting Covid from surfaces (e.g., masks) isn’t likely. The virus may not survive that long in real life due to light, heat, etc. Rotating the use of 3 masks (one per day) can be a good compromise between safety and re-use. Regardless, please also continue hand washing.

• More comfort with easier breathing and talking than cloth masks.

• Re-using is cost-effective and produces less waste.

• More practical and utility than double masking. While it’s a great alternative, double masking (preferably a cloth mask over a surgical mask) can be more troublesome and less comfortable. Although, it’s almost as effective as KF94/KN95 masks.

Intro

While the CDC advocates wearing cloth masks to reduce the spread of COVID-19, I’ve never felt that’s enough to prevent spread and protect myself and others. With more contagious variants circulating, experts now recommend double masking (preferably a cloth mask over a surgical mask).

Many Asian countries have had widespread adoption of higher quality masks [1][2] and have fared a lot better than the US, despite having similar population densities in certain areas. Some European countries have also begun to mandate better masks.

Masks like KF94s or KN95s provide more protection and comfort than average cloth or surgical masks. Re-using them is cost-effective and with few risks.

Caveat: Fortunately, I don’t need to go into an office every day, so my usage only consists of grocery trips and other errands. This amount totals only a few hours per week.

One more thing: One of the best ways to mitigate the complications of Covid-19 is to maintain a healthy diet and lifestyle. Lower intake of processed foods, seed oils, and simple sugars as much as possible. Get plenty of exercise and sunshine (or vitamin D) [3][4][5]. Multiple studies support how metabolic dysfunction can impair your immune system and worsen outcomes [6][7][8][9].

Aaron Collins

Over the past half-year, Aaron Collins, a mechanical engineer who wrote his masters’ thesis on aerosols, has selflessly spent hours testing numerous masks (mainly KF94 and KN95s). In full transparency, he compiled all his data and observations in a Google Doc. The videos he posted on YouTube also highlight the sizes and features of different masks. He’s taken a lot of his own time to reply to questions and comments on both YouTube and Reddit. He deserves special recognition because most of this is based on his dedicated work.

Re-use

Most KF/KN masks he tested were well above 90% efficient. After around 40 hours of use, he only noticed a 2-3% reduction with BOTN KF94 masks.

Another BOTN mask was used randomly, kept in the car for over 3 months, and accidentally left in the rain. After drying, it was still 90% effective.

Cloth Masks

The two cloth masks he tested had 53% and 55% filtration efficiency.

Surgical Masks

Filtration efficiency of different loosely worn surgical masks vary widely: 11%, 27%, 41%, 76%, 84%

However, mask filtration jumps up to 80-90% once held snug against your face (e.g., cloth mask on top).

Conclusion

Even a heavily used KF94 or KN95 is still vastly more effective than any simple cloth or surgical mask.

Collins’ personal opinion on mask re-use based on his tests and observations:

• 30–40 hours in a clean office-type environment.

• Fewer hours if you're in a construction-type environment or if you're exposed to a lot of aerosol.

• If you're in a super-clean environment, potentially even more than 30–40 hours.

Is It Safe?

Most likely

Early studies of the virus' lifespan on surfaces were conducted in a tightly controlled laboratory, not a real-world setting. Based on recent evidence, there may be no reason to disinfect surfaces obsessively. The virus may not survive that long in everyday life. Temperature, light, humidity, and ventilation all affect virus viability and concentration. Regardless, regular hand washing is still necessary.

Also, the severity of Covid may depend on the amount of viral load you’re initially exposed to [10][11][12][13].

Less virus = fewer complications.

Note: Most KF/KN masks are not designed for cleaning, so it’s probably not a good idea. It can affect mask integrity.

Fit

KF/KN masks come in various shapes and sizes, so you can probably find a good match. I like the boat-style, which are mainly KF94s. Its design allows it to conform to a wider range of faces than other types.

In Collins’ videos, he takes a lot of time to compare masks and demonstrate how to get a good fit/seal.

Also, many people on r/Masks4All are eager to help with suggestions.

Comfort

I’ve found that KF94 or KN95s are vastly more comfortable than an average cloth mask that hugs every inch of your face and chafes your lips when you talk.

Depending on the fabric and layers, your voice may be more muffled with cloth masks. Double masking makes it worse. KF/KN masks solve this issue while also being more breathable.

Cost

A 10 pack of Bone Fide Powecom KN95 Masks is $12.50, which comes out to $1.25 per mask.

A 10 pack of Bluna KF94 masks (my personal favorite) at Be Healthy USA is $28.00 (after a 20% promo that’s usually ongoing), which comes out to $2.80 per mask. They offer bulk discounts, which can push down the price further. While somewhat expensive, the comfort, utility, and safety profile justify it for me.

A 50 pack of AmazonCommercial 3-ply disposable face masks is $19.00, which comes out to $0.38 per mask. Even if you use the same one for 2 days, it still comes out to $1.14 per week. I can’t speak to the filtration ability over time for surgical masks.

A 3 pack of Old Navy cloth face masks is $12.50, which comes out to ~$4.17 per mask.

Purchasing

Note: There are many counterfeit masks on the market (especially on Amazon and eBay), so be careful. KF94s have had more consistent quality among the masks Collins tested.

Be Healthy USA is a popular choice for KF94s. They’re based in New Jersey and ship to the continental US and Canada. You can find masks in large, medium, or small.

Another site I’ve seen mentioned frequently is YesMask.

Ending Note

Hope you all stay safe and healthy. And err to be kind.

If anyone has more reputable sources for face masks, I’ll gladly add them.