The previous post is essentially the background on this topic: https://grieve-smith.com/ftn/2026/02/so-you-want-to-monitor-...

> Why carbon dioxide? Because everyone who exhales COVID (or flu, or RSV) aerosols also exhales carbon dioxide, and good ventilation removes both disease aerosols and CO2. Under many conditions, the concentration of CO2 particles in a space can give us an idea of how much risk there is of catching or passing on a respiratory disease.

> Unfortunately, the relationship between the numbers on a carbon dioxide monitor and the disease risk is complicated, so there are some things to know if you want to do your own monitoring.