>Outside air is just above 400ppm In 2015 it was, sure. We'll probably hit a seasonal peak of 420ppm next year. https://gml.noaa.gov/ccgg/trends/ https://gml.n

>Outside air is just above 400ppm In 2015 it was, sure. We'll probably hit a seasonal peak of 420ppm next year. https://gml.noaa.gov/ccgg/trends/ https://gml.noaa.gov/ccgg/trends/ RCP8.5 has us at 1000ppm by the end of the century. By then outside air ventilation will mostly be needed to keep people in meeting rooms from putting themselves into a coma.