Here it says there are some problems with CO2 not being evenly distributed. https://www.sciencedirect.com/science/article/am/pii/S0360132320306491#:~:text=The%

Here it says there are some problems with CO2 not being evenly distributed. https://www.sciencedirect.com/science/article/am/pii/S0360132320306491#:~:text=The%20ISS%20internal%20environment%20has,lack%20of%20natural%20convective%20flows https://www.sciencedirect.com/science/article/am/pii/S036013.... But a quoted source says it was by design, and essentially just a bad design. The air scrubbers were meant to keep CO2 levels at what is now thought to be much too high. https://www.smithsonianmag.com/air-space-magazine/why-living-space-can-be-pain-head-180951507/ https://www.smithsonianmag.com/air-space-magazine/why-living...