Shielded hoods: better than masks?

Update 2021–02–06: turns out there’s a reason masks are used. See details at the bottom.

The problem with masks, as everyone knows, is that you can’t see people’s faces. They also get hot and fog up glasses. But we wear masks anyway because they are the best way to reduce the spread of COVID-19. One alternative is face shields, but they don’t filter the air.

I’ve got a better idea, but I don’t have the time or fashion skills to persue it. I’m posting this in the hopes that someone with the time and inclination will take the idea and run with it.

You’ll probably like or hate the idea right away, so I’ll cut to the chase and provide details at the bottom.

A loose, comfortable hood sealed around a plastic face shield. The hood is made of breathable fabric which acts as a filter. The face shield is made out of non-fogging plastic (PETG) film, which is cheap and readily available.

Just like a mask, most or all of the air is forced through the fabric, trapping aerosols. However, the face is completely visible and it doesn’t need to fit precisely. It provides the best features of masks and face shields, possibly protecting better than either alone.

There are many ways to design this, some more stylish than others. The most straightforward is based on a hazmat hood design:

Alternatively, it could be integrated into a stylish hijab:

Or a wimple:

A 15th century 4-ply wimple, which could easily be adapted to include a face shield

Or a beekeeper’s hat:

Here’s a quick prototype, using one of my 3D printed face masks, an unmodified T-shirt, and a few clips:

An arabesque look

As you can see, fashion isn’t my strong suit. But maybe it’s yours.

There are lots of possiblities for layering fabrics. For example, soft cotton on the inside and fashionable silk on the outside.

Whatever the design, there are several important considerations:

1. It needs to be washable. The plastic can be washed using glasses cleaner, while the fabric should be machine-washable. The plastic and fabric should be held together with removable clips, pins, or magnets.
2. It needs to provide over 60% filtration. The fabric needs to be thick enough to be an effective filter. The WHO recommends three layers, while the CDC recommends at least two layers. Thicker isn’t necessarily better. An ideal filter is breathable enough that air passes through it, rather than forcing air through larger gaps.
3. It should look and feel good.

I’ve been 3D printing face shields since March. I’ve donated some to a local hospital, others I’ve worn myself. For comfort and communication, I much prefer a face shield to a mask.

There are many 3D printable face shield designs that have been approved by the National Institutes of Health for emergency use. I’ve been printing this one. It consists of a 3D printed clip and a sheet of transparency film. A 3-hole punch is used to make the holes to attach the film to the clip. The clip is comfortable, and the mask stays in place — except in the wind, where a hat keeps it from flying off.

It turns out that standard transparency film, made of PET/PETG plastic, is resistant to fogging. It’s what’s used in real hazmat hoods. It’s also inexpensive and available online or at office supply stores. I bought 100 sheets for $15 on Amazon. If you buy some, make sure it’s PET or PETG.

Researchers from Florida Atlantic University’s College of Engineering and Computer Science have found that face shields may not be as effective as masks. Aerosolized droplets go through the bottom and around the sides. They tested with mannequins that were modified to cough and sneeze, and viewed the simulated breath using green lasers.

With COVID-19, the main threat is not coughing or sneezing, but breathing. Particularly with asymptomatic, infectious people who are doing breathy activities such as talking or singing. It takes 15 minutes of close proximity to get infected. So face shields may not be a total loss, especially outdoors.

The best analogy I’ve heard is that the COVID-laced aerosolized droplets are like cigarette smoke. If COVID-19 viruses looked and smelled like smoke, you could avoid it easily, so long as you aren’t forced to be in a poorly ventilated room. Imagine how much social distancing and wearing a mask might protect you from cigarette smoke. Imagine if the smoker were also wearing a mask — yet somehow also able to smoke. You don’t need to block 100% of the virus to drastically improve safety.

There’s some evidence that masks combined with face shields or even glasses may be more effective than a mask alone. So a hood might actually be safer than a mask.

If you think you’re up to the challenge, let me know. I’m not looking for money or fame, just a better way to protect people.

Update 2021–02–06

I ended up making several prototypes before I had one that fit properly. When I put it on, it quickly filled with moisture and carbon dioxide.

I was reminded of a scene in 2001: A Space Odyssey, where they show that CO2 makes you hyperventilate. Turns out that’s absolutely true. If I don’t look happy in the picture below, that’s why.

Final prototype. My daughter says I look like I’m in a lamppost.

Because masks sit right in front of the mouth, they force fresh air in and stale air out. To make a hood work, you would need a fan to force airflow.

At that point it became clear that a hood cannot be made effective for anywhere near the price of a face mask. There are super-expensive hoods on the market, but nothing really practical. Nor does it look like there will be.

So for now, just wear the best mask you can get your hands on.