How to Use Ventilation and Air Filtration to Prevent the Spread of Coronavirus Indoors

The vast majority of SARS-CoV-2 transmission occurs indoors, most of it from the inhalation of airborne particles that contain the coronavirus. The best way to prevent the virus from spreading in a home or business would be to simply keep infected people away. But this is hard to do when an estimated 40% of cases are asymptomatic and asymptomatic people can still spread the coronavirus to others.

Masks do a decent job at keeping the virus from spreading into the environment, but if an infected person is inside a building, inevitably some virus will escape into the air.

I am a professor of mechanical engineering at the University of Colorado Boulder. Much of my work has focused on how to control the transmission of airborne infectious diseases indoors, and I’ve been asked by my own university, my kids’ schools and even the Alaska State Legislature for advice on how to make indoor spaces safe during this pandemic.

Once the virus escapes into the air inside a building, you have two options: bring in fresh air from outside or remove the virus from the air inside the building. Read More

Also See:
Aerosols Are a Bigger Coronavirus Threat than WHO Guidelines Suggest – Here’s What You Need to Know
The Constitution Doesn’t Have a Problem with Mask Mandates
Mask Resistance during a Pandemic Isn’t New – in 1918 Many Americans Were ‘Slackers’

In discussions of what precautionary measures churches should take to reduce COVID-19 transmission risks, the need for good ventilation is one of the most neglected areas. In its initial recommendations which the White House withheld from the public the Centers for Disease Control recommended that church services should be held outdoors or in a large, open room with its doors and windows open and ventilated by electric fans.

Holding a gathering outside will not by itself reduce transmission risks. The participants will also need to wear face masks and maintain social distancing. In addition the size of the gathering should be limited. A number of COVID-19 outbreaks have been traced to large outdoor gatherings where the participants stood or sat in close proximity to each other and did nor wear face masks. Like holding a gathering outdoors, limiting the size of the gathering will not by itself reduce transmission risks. Clusters of new COVID-19 cases have been traced to barbecues and other small outdoor gatherings where the participants were not wearing face masks or maintaining social distancing.

The scientists who published an open letter to the WHO calling upon that organization to recognize the growing body of evidence of the airborne transmission of the COVID-19 coronavirus drew attention to the inadequacy of ventilation systems that recirculate the air in a room or building rather than exhausting stale air and replace it with fresh air from outside.

Too many churches have not kept abreast of the latest research findings and are following outdated and inadequate guidance. A number of churches are ignoring guidance entirely and are endangering the health, safety, and well-being of their congregations and their communities.