Peter, this is such great info. Others should know it! Based on your advise I bought an "InkBird" NDIR sensor. When I take the sensor outside I get readings like 475, so I am guessing that the sensor is pretty accurate since that is likely within 50 ppm of the actual level on my balcony. Does that sound right to you???
I don't think this sensor calibrates to the outdoor level on its own however, so should I purchase a different one?
Using this sensor I find it tricky to keep my room below 1,000. Right now its the dead of winter, so keeping the window open a large amount is challenging. Still I plan to keep playing with the use of fans for circulation etc.
For both health and cognition what is the upper end of the target you would be aiming for (1) during my working hours, and (2) during my sleeping hours.
p.s. I think you should write a few more posts on this stuff, I think folks just dont know about it.
p.p.s. here is the sensor I bought:
