Would magn. pole reversal actually mess up electronic equipment?

Oh, you grossly underestimate the capabilities of human beings. 10x CO2 would be 0.3%, but CO2 becomes dangerous around 3 to 5%, and lethal between

8 and 10%. So we have a headroom of a factor 100 for CO2. There is some reason for that - the air we exhale under normal condition contains ~4% CO2, so that's why similar CO2 concentrations in the air start to become uncomfortable - and even a fraction of those (e.g. 1%) can be noticed through the increase of breathing frequency and/or volume.

Basic algorithm for idle breathing: Inhale (+500ml). Exhale (-500ml). Stall until CO2 concentration > 4% (~50% of saturation level). Repeat. 50% saturation level is an obvious point for optimal resource usage.

--
Bernd Paysan
"If you want it done right, you have to do it yourself"
http://www.jwdt.com/~paysan/