The air in schools

As my epidemiological interests have shifted since the conversation has increasingly moved to schools and public places, indoor air quality experts Richard Corsi and Joseph Allen have been indispensible follows on twitter.  Here they team up to explain what we need to do, air quality-wise, if we’re going to let kids in schools.  Obviously, there’s lots of other concerns– especially amount of spread in the larger community– but insofar as many districts are sending kids back in person, period, we should have the best science guiding us on the air the kids are breathing and how that relates to viral transmission:

We have limited time and funds to get students and teachers back to school safely, but we can — and must — do it. Here’s how.

Start with the fact, as 239 scientists recently wrote to the World Health Organization (WHO), that airborne transmission of the novel coronavirus is happening. This is not to be feared; it just requires adding some new strategies to our arsenal in addition to hand-washing, distancing and other measures to keep community spread to a minimum. (Just because we reopen schools doesn’t mean we should reopen elsewhere.)…

A: Air cleaner in every classroom

Portable air cleaners, also known as air purifiers, may be the fastest way to clean the air quickly indoors. A portable air purifier with a HEPA filter that is correctly sized for the room can deliver three air changes per hour of clean air, meaning all of the air in the room is cleaned every 20 minutes.

R: Refresh indoor air

Every effort should be made to determine how much more outdoor air can be brought into schools, but there are limitations. In summer and winter months, the amount of air that can be brought in from outside will be limited by the cooling and heating capacity of existing HVAC systems. While bringing in twice as much as the minimum ventilation standard would be an excellent strategy, there may not be enough time or money to fix all of these school ventilation problems in the next 30 days before kids come back to school. That doesn’t mean we shouldn’t try.

Schools should also upgrade recirculated air filters to MERV13 or higher. If schools rely on natural ventilation, get those windows open and use simple box fans to pull in outdoor air.

It’s time get creative and re-imagine classrooms. We don’t need to think about ventilation rates if we hold classrooms outdoors. Yes, there will be inclement weather — kids and teachers will have to wear hats and gloves when it gets cold, and papers will occasionally get blown around. But this is still far superior to learning via Zoom. A massive mobilization of tents for schools, maybe by the National Guard, could get us there. Think this is impossible? We’ve done it before, during the tuberculosis epidemic.

And here’s all the key points in one handy graphic:


On a very personal, practical level, my school system is starting almost all on-line, but not the Special Education classes (for the obvious reasons).  So, thanks to these guys I’m going to make sure my son’s classroom has an air filter that exceeds 300 CADR.

If you want to learn even more about this, Allen has a terrific twitter thread where he links to all their efforts via Op-Eds, etc., on educating the public on how to make schools safer.

And here’s the whole Healthy Buildings report for schools which is terrific.

“Hygiene theater” “fomitephobia” and opportunity costs

Sometimes you just read an article and keep saying, yes, omg, yes.  I love the experience of having had some semi-inchoate thoughts and then see somebody put them together just perfectly in an article and you can, say… this!  That was my experience with Derek Thompson’s recent Atlantic piece on how we are foolishly focusing too much on sanitation and not enough on air quality.  We’ve actually had good contact-tracing-based evidence for a while now that Covid-19 spread poorly (though, still at some low level) through surfaces (fomites, in epidemiological parlance).  And lots of evidence that it spreads well in poorly-ventilated indoor air.  So, where have so many institutions focused their efforts?  That’s right, cleaning surfaces.  And there’s a huge opportunity cost there because, all too often this provides “hygiene theater” (oh my do I love that formulation) that does far too little to protect us whereas the organization/business is saying “but, look what I did to make you safe.”  Naturally, Thompson draws the terrific parallel to “security theater” after 9/11 (and which we still live with to an absurd degree).  Anyway…

To some American companies and Florida men, COVID-19 is apparently a war that will be won through antimicrobial blasting, to ensure that pathogens are banished from every square inch of America’s surface area.

But what if this is all just a huge waste of time?

In May, the Centers for Disease Control and Prevention updated its guidelines to clarify that while COVID-19 spreads easily among speakers and sneezers in close encounters, touching a surface “isn’t thought to be the main way the virus spreads.” Other scientists have reached a more forceful conclusion. “Surface transmission of COVID-19 is not justified at all by the science,” Emanuel Goldman, a microbiology professor at Rutgers New Jersey Medical School, told me. He also emphasized the primacy of airborne person-to-person transmission.

There is a historical echo here. After 9/11, physical security became a national obsession, especially in airports, where the Transportation Security Administration patted down the crotches of innumerable grandmothers for possible explosives. My colleague Jim Fallows repeatedly referred to this wasteful bonanza as “security theater.”

COVID-19 has reawakened America’s spirit of misdirected anxiety, inspiring businesses and families to obsess over risk-reduction rituals that make us feel safer but don’t actually do much to reduce risk—even as more dangerous activities are still allowed. This is hygiene theater…

Surface transmission—from touching doorknobs, mail, food-delivery packages, and subways poles—seems quite rare. (Quite rare isn’t the same as impossible: The scientists I spoke with constantly repeated the phrase “people should still wash their hands.”) The difference may be a simple matter of time. In the hours that can elapse between, say, Person 1 coughing on her hand and using it to push open a door and Person 2 touching the same door and rubbing his eye, the virus particles from the initial cough may have sufficiently deteriorated.

The fact that surface areas—or “fomites,” in medical jargon—are less likely to convey the virus might seem counterintuitive to people who have internalized certain notions of grimy germs, or who read many news articles in March about the danger of COVID-19-contaminated food. Backing up those scary stories were several U.S. studies that found that COVID-19 particles could survive on surfaces for many hours and even days.

But in a July article in the medical journal The Lancet, Goldman excoriated those conclusions. All those studies that made COVID-19 seem likely to live for days on metal and paper bags were based on unrealistically strong concentrations of the virus. As he explained to me, as many as 100 people would need to sneeze on the same area of a table to mimic some of their experimental conditions. The studies “stacked the deck to get a result that bears no resemblance to the real world,” Goldman said.

As a thousand internet commenters know by heart, absence of evidence is not evidence of absence. But with hundreds, and perhaps thousands, of scientists around the world tracing COVID-19’s chains of transmission, the extreme infrequency of evidence may indeed be evidence of extreme infrequency.,,

Hygiene theater can take limited resources away from more important goals. Goldman shared with me an email he had received from a New Jersey teacher after his Lancet article came out. She said her local schools had considered shutting one day each week for “deep cleaning.” At a time when returning to school will require herculean efforts from teachers and extraordinary ingenuity from administrators to keep kids safely distanced, setting aside entire days to clean surfaces would be a pitiful waste of time and scarce local tax revenue…

As long as people wear masks and don’t lick one another, New York’s subway-germ panic seems irrational. In Japan, ridership has returned to normal, and outbreaks traced to its famously crowded public transit system have been so scarce that the Japanese virologist Hitoshi Oshitani concluded, in an email to The Atlantic, that “transmission on the train is not common.” Like airline travelers forced to wait forever in line so that septuagenarians can get a patdown for underwear bombs, New Yorkers are being inconvenienced in the interest of eliminating a vanishingly small risk.

Read the whole thing– it’s great.  I suspect I’m going to be sharing this article a lot.

And while I’m at it, a great comment from (my literal “best man”) and my response:

And, really, this explains so much of life (I’ll refrain from a digression into university assessment of learning outcomes here, among other things).  And, it’s relatively easy to say– look– we wiped down everything.  Much harder to ensure that your indoor air is undergoing frequent changing and has high-quality filtration.  Of course, you’d think masks would be easy, but… America :-(.

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