Our best option in a high pollution area is to live in a building that has made a good internal filtering system. I think it’s extremely difficult to setup in a

Our best option in a high pollution area is to live in a building that has made a good internal filtering system. I think it’s extremely difficult to setup in an individual house. However, the outside air will not be high co2. That’s equal enough worldwide. I’m in a city and it’s about 450 ppm outside. Higher than global average but still fine for ventilation. If you also measure particulates, you can get a sense of whether simply opening a window is sufficient.