Here's a recap from about a year ago covering some of the evidence for ventilation and filtration: https://yourlocalepidemiologist.substack.com/p/the-power-of-

Here's a recap from about a year ago covering some of the evidence for ventilation and filtration: https://yourlocalepidemiologist.substack.com/p/the-power-of-ventilation-and-filtration https://yourlocalepidemiologist.substack.com/p/the-power-of-... > A study last summer found that open windows in classrooms can have up to a 14.1 fold reduction in COVID19 transmission. > Another study found that one HEPA filter is as effective as two windows partly open all day during the winter (2.5-fold decrease in transmission). Two HEPA filters are even more effective (4-fold decrease in transmission).