What’s the best MASK to protect me from the Delta variant?

COVID Variants Masks

A: A well-fitted, high filtration mask such as N95, KN95, FFP2 or KF94.

⚠️ Delta is more transmissible, in part due to infected people shedding more virus from their nose and mouth.

While vaccination is still your #1 defense against Delta, it’s also a good idea to UPGRADE YOUR MASK when you are in higher risk indoor situations.

Ah, those naïve early days of Spring 2020 when we learned how to sew cloth masks and built a collection of our favorite designs and sports logos.

😍 Look how cute the Nerdy Girls were in our cloth masks circa May 2020!

In retrospect this did make sense—cloth masks ARE better than no mask and N95 respirators were in scarce supply for frontline medical personnel who needed them most.

But 18 months later we have more knowledge of the extent of airborne transmission, a more transmissible variant AND more widely available high-quality masks.


Remember the 3 keys to mask effectiveness:

💥Filtration generally refers to the percentage of particles the mask material blocks. For example, an N95 filters at least 95 percent of airborne particles.
💥A well-fitted mask should sit snugly against the face and over the chin, with no gaps around the nose or mouth. See this cool new paper on the difference improving fit can make to blocking inbound aerosols (See figure below.)

💥Comfort is extremely important (especially for kids)—a mask you *use* consistently is much better than one that is uncomfortable and gets fiddled with a lot or not used.

❇️ Nerdy Girl mask ranking ❇️:


2️⃣KF94 (Korea), FFP2 (Europe), KN95 (China-buyer beware: manufacturer should hold a ‘NIOSH Certificate’)

3️⃣ Double-mask (cloth mask on top of surgical, OR cloth mask with filter insert)

4️⃣Surgical mask

5️⃣Good fitting cloth mask

Options 1-3 provide both good filtration AND fit; besides the gold standard fitted N95, differences among these will be small so use what’s available & fits you.

Option 4: good filtration but gaps

Option 5: good fit but less filtration

🏃🏽‍♀️ CONTEXT MATTERS: Choose masks based on type of activity. If you are outdoors & not near a lot of people, cloth is likely fine. But for indoor environments for long duration or with lots of close contact, definitely upgrade your protection to a higher-ranking option.

Also remember that any mask you *use* consistently is much better than one that is uncomfortable and gets fiddled with a lot. This applies to children for whom finding something they will consistently wear is a high priority. The best mask is the one that fits, is comfortable, and is WORN. DON’T LET THE PERFECT BE THE ENEMY OF THE GOOD.

⁉️ We get lots of questions about SPECIFIC brands of masks, so we are dropping some links for sources that vet different brands:

😷 🤓 “Mask Nerd” Aaron Collins is a mechanical engineer with a background in aerosol science who makes YouTube videos testing high-filtration masks made by various manufacturers.

➡️ His top picks overall

➡️ For kids’ masks

➡️ Kids’ mask suggestions from Dr. Linsey Marr & team

➡️ Links for legitimate KN95s:

Project N95

Bona Fide Masks


Those Nerdy Girls


“Why We Need to Upgrade Our Face Masks—and Where to Get Them”

“Why Are Americans Still—Still!—Wearing Cloth Masks?”

Link to Original FB Post