Everyday Clean Air

When the next pandemic hits, our ability to stop it will depend on the infrastructure we already have in place. A key missing piece is clean indoor air. An airborne pathogen can be very hard to contain, and we would want to move fast to limit spread. But how quickly we can get measures in place, and how thoroughly they would work, depends critically on the base we have to build up from.

Indoor air today is dirty by default. The air you breathe in is air others have breathed out, complete with a wide range of viruses and bacteria. It’s a little gross if you think about it, and people do get sick a lot, but most of the time we just accept the downsides.

If something really serious were going around, though, this isn’t a risk we’d accept. We’d need clean air: some combination of replacing infected air with outside air (ventilation), physically removing pathogens (purifiers, masks), or inactivating pathogens (far-UVC, glycol vapors).

I hear a lot about stockpiling as a way to set us up for clean air when we most need it. Get a lot of masks, air purifiers, far-UVC lamps etc ready to go, so they can be distributed in an emergency. I do think this helps, but there are serious limits:

• Manufacturing capacity will stay low, because there’s no ongoing demand. Compare to masks in 2020: there was a huge spike in demand for N95s but it took many months to ramp up production.

• There won’t be many experienced installers, and people won’t be familiar with the logistics.

• Products will be relatively expensive and poorly designed, because product improvement runs through things actually being used.

• When deploying in an emergency people won’t be familiar with them, and so would be hesitant to use them.

• As an expensive speculative investment you probably can only afford to stockpile enough for the most critical applications.

What we need is regular (”peacetime”) deployment. If a significant fraction (10%?) of rooms already had air purifiers, far-UVC, or other good options, not only would some need already be covered, but all the factors I just listed above work in your favor. You’d have the manufacturing capacity, the experienced installers, the good cheap products, and the public familiarity.

Key to peacetime deployment is peacetime benefits. You’re not going to get to 10% of indoor spaces on the threat of a future pandemic. But millions of people die from airborne disease every year, people miss school and work, and being sick is just unpleasant. Cleaner air lets us make progress on all of these. While I’m coming at this from a biosecurity angle, the public health and economic benefits are also substantial.

I especially think it would be valuable to have more quantification here. If I’m an employer, how much will my company healthcare costs and sick days decrease if I deploy effective air cleaning? If I’m a superintendent in a district where I lose $50 each day each student is absent, how long before a given air cleaning system would pay for itself?

More demonstration would also be valuable, especially if the effects are as large as I expect them to be when you cover a large portion of someone’s weekly exposure. If kindergartens with clean air have ~half the absenteeism they used to, that would be such a clear effect that people could see it in their own experience. You wouldn’t need to present complicated statistics and discuss randomization approaches if the benefits were staring us in the face. I could point to the experience of Germantown Friends School in 1937, but we need examples that aren’t 88 years old.

It’s counterintuitive to advance biosecurity by focusing on everyday public health, but it pencils out. We clean drinking water all the time, not just in response to cholera outbreaks. To have clean air in emergencies, figure out how to have clean air every day.