Ventilation

COVID-19 is an airborne disease. Cleaner air = safer air.

The Ventilation FAQ

The folks who wrote these Qs and As are the absolute experts in the field. You want to know something about ventilation and COVID? You can find it here.

Bring in the fresh air. Image by Bruno /Germany from Pixabay.
School Ventilation: A Vital Tool to Reduce COVID-19 Spread
(Johns Hopkins Center for Health Security, 05.2021)

The companion piece to the Lancet report. Take-homes:

  • Bring in as much air now as you can, and improve air filtration.
  • Use HEPA filters.
  • Don’t put anything INTO the air – just take stuff OUT, using either HEPA filters or UVGI.
  • Stop “deep cleaning.” It’s a waste of time and money.
  • If your ventilation systems isn’t up-to-date, get it up-to-date now.
Even if your classrooms are this old-fashioned, your ventilation systems shouldn’t be.
Photo by Jeffrey Hamilton on Unsplash.
Designing infectious disease resilience into school buildings
through improvements
to ventilation and air cleaning
(The Lancet COVID-19 Commission on Safe Work,
Safe School, and Safe Travel, 04.2021)

Don’t worry, it’s shorter than the title makes it seem – only five pages of content plus references. Includes five big takeaways:

  • Have pros check buildings and their ventilation systems regularly.
  • Ventilate with clean outdoor air.
  • Improve buildings’ air-cleaning efficiency using methods that aren’t snake oil.
  • Use portable air cleaners with HEPA filters if you have to.
  • Consider other strategies as long as there’s good evidence that they work – like UVGI systems.
Smoke rising. Just like breath does.
Image by Brigitte makes custom works from your photos, thanks a lot from Pixabay.
Safe Spaces: How to Reduce Virus Risk Indoors
(University of Oxford)

Fabulous animated video on how to improve indoor air quality/safety. Clear and easy to understand, even if you don’t have the sound on (bonus!). Illustrations mostly invoke businesses, but info is appropriate for schools too – just swap out “productivity” for “learning.” Found this on the FreshAirSchools Resource Centre, a wonderful site dedicated to improving school air quality and safety.

Kids went back to school wearing masks this spring.
Image by Elf-Moondance from Pixabay.
Ventilation, masks, and testing worked. Here’s evidence.
(NY Times, 05.21.2021)

CDC studies in Georgia and Utah showed the benefit of improved ventilation, masking, and COVID testing in preventing outbreaks in K-12 schools.

A blacklight bulb.
Image by TheLight from Pixabay.
If you’ve got high ceilings, UVGI can keep your air cleaner. (Science Daily, 11.20.2020)

UVGI is shorthand for Ultraviolet Germicidal Irradiation, and it actually does work, because UV light kills viruses. However, it also can harm people, so you don’t want to bathe the whole room in it while folks are there.

Solution: Install UVGI units up near the ceiling. People breathe out viruses –> their warm breath rises up to ceiling level –> UVGI units zap viruses. Cool, huh?

School SMART graphic from the Harvard T.H. Chan School of Public Health’s Healthy Buildings campaign. Make it your mantra.
How to Improve Ventilation
On the Cheap

While we wait for government funds to cover major-league improvements to school ventilation, there are quick, inexpensive things we can do to decrease the likelihood that SARS-CoV-2 particles are contaminating classroom air. This list of “hacks” from CovidStraightTalk can help.

Want to buy portable air filters for your classrooms? This doc, developed by the San Francisco Department of Public Health, tells you everything you need to know. Should you even bother buying them? What does all the jargon mean? What kind should you buy? Once you’ve got them, where should you put them? It’s all spelled out.

Only want to buy filters that have FDA approval specifically for removing coronavirus? Here you go.

Two Apps to Help Maximize Classroom Safety

How long can 15 students safely stay in a 900-square-foot classroom while masked, seated, and talking? How about 20 students in a 1200-square-foot classroom? This app, from fluid dynamics researchers at MIT, lets you input your school’s parameters to find out what works.

According to this model of COVID-19 aerosol transmission from the Max Planck Society, opening windows every hour, having everyone wear masks, and decreasing the number of students from 25 to 12 took the probability of infection in a classroom from 90% to 12%. You can enter parameters for your own rooms and see how your risk changes.

Person in mask with virus particles. Image by Tumisu from Pixabay.
Wear Masks, Use Good Filters,
and Open the Windows

Ok, the CDC does care about ventilation, too. Here are their recommendations for schools and childcare settings. If you’re wondering what they recommend, read the headline above this paragraph.

If you want much more detailed advice, go to the WHO’s Roadmap to Improve and Ensure Good Ventilation in the Context of COVID-19 and scroll to p. 23 (non-residential settings).

If you’re a visual learner, check out the NY Times’ animation on how ventilation dilutes coronavirus-carrying aerosols in a classroom.

Image by elizabethaferry from Pixabay
One Type of Indoor Area
Is Especially High-Risk
For COVID-19

(Inverse, 12.15.20)

A study found that “moving people leave behind a floating bubble of virus-laden droplets or a trailing, virus-containing cloud. In a narrow corridor, this cloud becomes concentrated — posing more danger to those coming behind than it otherwise would in a larger, open-air space.” Take-home message: ventilate your corridors as well as you can!

Image from Kwon KS et al.
Six Feet of Distance Isn’t Enough
If the Airflow Is Right

(LA Times, 12.09.20)

Thanks to Korea’s unparalleled contact tracing, this study was able to show how an unmasked restaurant diner was infected in 5 minutes from more than 20 feet away.

Why does this matter for schools? Because if you’re serving meals, six feet of distance between your students may not be enough. (emphasis added)


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