--- > For decades, that’s how aerosol scientists and ventilation engineers have mostly thought about CO2 — as a sort of indicator for the health of indoor environments. But over the last three years, researchers in the U.K. working with next-generation bioaerosol technologies have discovered that CO2 is more than a useful bystander. In fact, it plays a critical role in determining how long viruses can stay alive in the air: The more CO2 there is, the more virus-friendly the air becomes. - [View Highlight](https://read.readwise.io/read/01j155eq9fmgcd1h6wjevwxjre) ---