I got a carbon dioxide sensor (along with Netatmo weather station indoor sensor) couple days ago, and wondered if I should be concerned of my bedroom readings. I think… well… after seeing your blog post, not really!

What are my bedroom readings, then? Ambient reading when I’m not at home is 400 ppm (since that’s what the device self-calibrates to, but I believe it’s not more than 10% off from the truth), and almost always between 600 and 700 ppm when I’m in my bedroom.

Once I saw these numbers I got curious about regulations. I’m relatively confident they are different here (Finland) from those in the US. It actually turns out that my measurements are perfectly in line with regulations: required air circulation on newly built households is about 0.5/hour — which means that the air volume equivalent to the apartment volume is ventilated through it every two hours. If my back-of-an-envelope calculations are not horribly off, this leads neatly to the ballpark of 250 ppm rise of carbon dioxide for one adult in my roughly 45 square meter apartment.

There are also regulations on “interior climate”, of which the maximum carbon dioxide level is one criterion. <700 ppm is “very good” by Finnish standards, <900 ppm is good, and <1200 ppm… is a level which all new households should be able to support.

As a point of comparison typical readings at my office workplace stay below 700 ppm on regular days, and approach 1000 ppm on days with significant crowding (which occurs only couple hours of a month at most).

Thus I think I’m either very lucky, or your readings are pretty alarming.