I started monitoring CO2 levels at conferences a couple years back, and now that we're having in-person conferences again, I'm doing more monitoring.

The last I attended was EPOS 2022, which is probably my favorite recurring conference because of its venue, size, and schedule. There is time to talk to everyone you want to about all topics.

I gave a talk on the small disks in Orion.

The monitoring results are here:

I missed day 1 because I forgot the USB cable in my room, then I had some electrical connection problems day 2 (the USB-C port on my computer is... finnicky). But besides that, you can see clear trends on day 1 and part of day 2 where the CO2 was rapidly rising to uncomfortable levels.

The blue zones are the scheduled breaks. During the breaks, the room was almost totally empty and we usually opened the doors and windows.

I shared the day 2 data with the conference organizers and they then prioritized opening the windows. There was one period I think we opted not to because it started snowing for a few minutes.

On the last day, I'm not sure why the CO2 didn't go down during the break - it may be that windows were open only one one side of the room, so there was only diffusion, not flow.