I have a CO2 monitor, and with all the windows open the range is ~400-430. There is very little variation globally. 250 is not a reading you can find anywhere

I have a CO2 monitor, and with all the windows open the range is ~400-430. There is very little variation globally. 250 is not a reading you can find anywhere on earth anymore. CO2 diffuses very very quickly so global readings are very close to the global average.