Thread by @bopinion

Eighteen months into the pandemic, we’re entering a new phase. While we have better Covid protection from vaccines and natural antibodies, we’re also returning to high risk environments like night clubs and offices.

What does that mean for face masks? trib.al/ntQaaQY

Research suggests that most of us can de-mask without guilt or worry in many instances — and not just outdoors.

Unfortunately, that doesn’t mean ditching masks entirely. Instead, it’s time to get tactical trib.al/ntQaaQY

Numerous studies have shown masks help a lot:

Transmission is most reduced when an infected person wears a mask. But wearing a mask also protects you from getting the virus.

If both parties wear a mask, the risk of transmission drops by more than 90% trib.al/ntQaaQY

U.S. states that had high mask usage one month avoided high Covid rates in the subsequent month even after adjusting for masking policy, distance policy and demographic factors.

In contrast, most states with low mask usage ended up with high case rates trib.al/ntQaaQY

But it’s not just the act of wearing the mask that matters. What masks we wear, and especially how they fit, is key.

While N95s offer a higher level of protection, a well-fitted surgical mask blocks most particles trib.al/ntQaaQY

One myth is that masks increase the amount of CO2 the user breathes, leading to feelings of illness or tiredness.

🦖But if a CO2 molecule were the length of a T-Rex, then the average pore size of an N95 mask would span a country the size of Italy 🇮🇹 trib.al/ntQaaQY

Denser reusable mask fabrics are much more effective than loosely woven scarves or cloth.

The design of face coverings can also make a big difference. Leaks can significantly reduce a masks’ effectiveness trib.al/ntQaaQY

Layering masks can also improve efficacy. A three-ply surgical mask blocked 42% of particles from a simulated cough; a three-ply cloth mask was pretty similar.

But the protection jumped to 92% when a cloth mask was worn over a surgical mask trib.al/ntQaaQY

Many of us aren’t wearing masks correctly, and that reduces efficacy by quite a lot.

Gaps, diaphanous cloth masks, scarves doing double-duty – all allow aerosols to penetrate or escape from them trib.al/ntQaaQY

Finding the right mask is highly personal. It can be particularly hard if you have:

👧🏽A small face
🤓Glasses
🧔🏻A beard

Here are some strategies for plugging the leaks:

Comfort is important to being able to wear a mask for long periods of time.

In addition to metal strips that can help a mask stay on better, straps that tie behind the head & mask extenders can help reduce soreness around the ears trib.al/ntQaaQY

All of this research doesn’t begin to get at what makes masks so emotive. Masks act as a:

😷Barrier to effective communication, making us less able to connect with others
😷Jarring visual reminder of what we lost when we got hurled into the pandemic trib.al/ntQaaQY

As much as we’d like to see the end of masks, the high transmissibility of delta and declining vaccine protection means we need them in our routines.

Masks will help prevent more variants from emerging and flu infections trib.al/ntQaaQY

To know whether a mask is a good idea or superfluous, check the risk factors:

👥How densely packed and how well-ventilated is the space?
🏃🏿‍♀️Will you be moving around or stationary?
📈What are the infection and vaccination rates where you are? trib.al/ntQaaQY

For example, it’s certainly good to mask up in an elevator or on public transport where people are pretty close together.

It’s probably not necessary in an open-planned, well-ventilated office trib.al/ntQaaQY