Indoor air, explained by symptoms
The air in this room is probably ailing you.
Sleepy in meetings. Headache on waking. Brain fog by 3 pm. Before you blame yourself, check a number nobody can see: the CO₂ in the room, measured in parts per million. It's in our name — ppm · ail · me.
One scale for everything on this site
Every room you enter sits somewhere on this instrument. Outdoor air is about 420 ppm; a closed bedroom can pass 2,500 by morning. Each page pins its topic to the same scale, so the numbers start meaning something.
A typical mid-meeting reading in a small closed conference room. Details and citations on the CO₂ levels page.
outdoors · ~420 ppm · the reference
Which one is you?
Sleepy in every meeting
Four people, one closed door, forty minutes. It's often not the agenda — it's arithmetic. A small room gains roughly a thousand ppm an hour.
Why it happens →
Headache when you wake
Closed bedroom doors trap the night's exhaled air. Researchers measured what a cracked window does to sleep quality — and it's not subtle.
Why it happens →
Brain fog at the office
Feel sharper working from home? "Sick building syndrome" has a boring, fixable cause more often than a mysterious one: ventilation.
Why it happens →The whole method: measure, read, fix
- Measure. One NDIR CO₂ monitor (how to pick one) tells you in an afternoon what no amount of guessing will.
- Read. Pin your number on the scale. Below 800: not the air. Above 1,400: found your suspect.
- Fix. Usually free: a door left ajar, a window cracked, a meeting moved. For smoke and particles, a right-sized purifier — our CADR calculator does the sizing math.
Yes, the name is the thesis
Parts per million; it ails me. The unit of the problem, the verb of the symptom, and the person it happens to — the whole site fits in the domain name. We keep the rest equally plain: every claim cited to a primary source, every fix ranked by cost, starting at free. More about us →