@RadCentrism But for (1) the standard may have to really be "nearly". There are a lot of people pushing 800 ppm as "good" ventilation, that's not terrible but not close to outdoors.
@RadCentrism 但是对于（1），标准可能必须真正“接近”。有很多人将 800 ppm 推为“良好”通风，这并不可怕，但离户外也不远。