Comment by kettleballroll

In terms of air quality sensors, what really made a difference for me was getting a CO2 sensor. "Fresh air" (low CO2) behaves way different than what j was taught. I live in a newly constructed building, which apparently is almost hermetically sealed. And we have no AC, since we're in Europe. As a result, air quality (in terms of co2) goes downhill unexpectedly FAST. And opening the windows for 5 to let in fresh air is definitely not enough to restore quality to sensible levels. EU norms say that public building should have less than 800ppm CO2, as anything above might affect cognitive abilities. However, reaching that level is almost impossible without constantly cracking the window (or an AC). I'd never have expected this....