>Radon

I live in a high-radon part of the world (Appalachia), and there are so many more benefits to having an ERV[0] than just getting rid of toxic gasses (handles farts, too!). Worth every penny — one will remove stink from the entire 1000sqft house (including indoor cat litterbox), with partial heat/humidity recovery.

[0] Energy recovery vent, e.g. https://www.homedepot.com/p/Panasonic-WhisperComfort-60-20-5...