[throwaway81523]

Don't forget too, if the CO2 is 1000 ppm, then half of the air in each breath you inhale was recently exhaled by someone else. Yes, airborne viruses are still spreading. I still wear an N95 mask whenever I'm in an indoor space with other people outside of home.

IKEA now has a remarkably cheap ($35) air quality monitor that measures CO2 as well as PM:

https://www.ikea.com/us/en/p/alpstuga-air-quality-sensor-sma...

I don't have one yet but plan to pick one up soon. A CO2 sensor alone from Adafruit is $50+, though that one is more precise. I bought it a while ago and it's still sitting in my todo bin.

[boernard]

could you observe an effect on your health after starting to wear the mask? like sickness days per year?

[hypfer]

Doing that all the time might not be the best idea for your immune system and neither for the respiratory one too.

The first needs to occasionally see new threats to stay up to date and healthy. The second will not like the constantly restricted airflow.