Act on it

You measured it. Now act.

Sometimes the fix is simple. Open a window, prop the door, thin out the room. But often the room is just undersized or underventilated, and the only move is getting whoever controls the space to do something about it.

Do this first

Fast fixes anyone can do

  1. Open a window or prop the door. CO2 drops fast, often back to fresh within minutes.
  2. Take fewer people into small rooms. There is a capacity number on the door for a reason.
  3. Take a real break every 45–60 minutes and air the room out.
  4. If it's a recurring room, log it a few times so you have a pattern, not a one-off.
The rules on your side

Ventilation isn't a favour. It's a standard.

Workplaces are supposed to bring in fresh air, and CO2 is the accepted way to check whether they do:

UK
The Health & Safety Executive says CO2 consistently above 1500 ppm indicates poor ventilation that needs action. Guidance points to roughly 10 litres of fresh air per person per second for typical offices.
Sweden
Arbetsmiljöverket treats sustained CO2 around 1000 ppm as a sign of inadequate ventilation, with minimum airflow requirements per person and per square metre.
EU / intl.
Standards like EN 16798 and ASHRAE 62.1 set the ventilation rates buildings are designed to. A room that runs hot on CO2 usually isn't meeting them.
Not legal advice, just the widely published guidance. Check your own country's exact figures.
Copy, paste, send

The template: email to whoever runs the room

Pick your tone. Fill in the brackets. Hit send.

Subject: Air quality in [room name] — CO2 readings Hi [name], I wanted to flag something about [room name / the phone pods on floor X]. I measured the CO2 during a normal meeting on [date]. With [number] people in the room, it reached [XXXX] ppm. For context, fresh outdoor air is around 400 ppm, and published ventilation guidance treats anything sustained above [1000–1500] ppm as a sign the room isn't getting enough fresh air. At that level people get drowsy and lose focus, and there's solid research (including from Harvard) showing measurable drops in cognitive performance. It likely affects the quality of the work happening in that room. Could we look at improving the ventilation, or at least reviewing how many people the room is booked for? Happy to share my readings and re-measure once something changes. Thanks, [your name]

More templates coming — landlord, coworking space, formal escalation. Mailing list gets them first.