Prove it.

Measure your room.

The method

Five steps

  1. Get a CO2 monitor. It costs about the same as a nice dinner, and it lasts years.
  2. Put it in the room during a normal meeting. Real people, doors closed, like always. Don't cheat by opening a window first.
  3. Watch the number climb through the meeting. Note the worst reading you see.
  4. Check it against the scale. Under 1000 is fine. Over 1000 and the air is getting dumb.
  5. Open a window, prop the door, thin out the room. If it's a room you don't control, use your reading as evidence and take it to whoever runs the space. Do Something
Screenshot the worst reading with the time and how many people were in the room. That screenshot is your evidence.
LIVE · MEETING ROOM 3
430 ppm
400100015002500+
FRESH
The gear

Which monitor should you get?

One rule: it must have a real NDIR sensor. Not an "eCO2" estimate that guesses from other gases. NDIR measures CO2 directly. Everything else is noise.

Why NDIR matters → DUMB AIR buyer's guide →