Are we ready to close schools’ windows?

...When it comes to Covid-19, all else doesn’t remain equal for long. For the past nine months, the challenges we face have been constantly evolving, due to changes in the virus itself, our approaches to treating it, government policy, and human behavior.

And with winter on the horizon, now we face a new challenge: Our schools’ indoor air quality, which will soon become a critical issue when temperatures drop and the windows must close.

Last May, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) issued its initial guidance on indoor air quality to reduce COVID-19 infection risk (“Guidance for Building Operations During the COVID-19 Pandemic”).

One of its key recommendations was the use of filters rated at least MERV-13 in HVAC systems. These filters have small enough pores to catch most viruses. Unfortunately, many schools can’t use these filters, either because the filter housing is too small, or because they lack sufficient power to push a minimum quantity of air through them...

https://fordhaminstitute.org/national/commentary/are-we-ready-close-schools-windows