Indoor CO2 and brain fog

⁠
We breathe out CO2 all day, and some amount both inside and outside is completely normal and harmless. Typically, levels are around 300-400 ppm (parts per million) outside. Indoors, a concentration of 600-800 ppm is considered safe, but at around 1,000 ppm, people start to notice symptoms like drowsiness — still well under the “danger” threshold of 5,000 ppm. ⁠
⁠
A study at Berkeley showed that other abilities like initiative, information utilization, and basic activity levels all dropped at 1,000 ppm and severely dropped at 2,500 ppm. ⁠
⁠
If you have a “tight,” or energy efficient home, that’s fantastic for a lot of reasons, but does mean that fresh air can be hard to come by, and it’s much easier for CO2 to build quickly. After a night of two people sleeping in an energy efficient bedroom with a closed door, levels can rise to 1,300 ppm, for example. Having an indoor party with the windows closed can easily raise levels to 2,000 ppm. ⁠
⁠
Obviously the easiest thing to do is to open your windows!! If you’re concerned about energy efficiency, and can modify your exhaust system, you can consider Fresh Air Ventilation systems that both bring filtered outside air into the home and exhaust indoor air. And, if you’re like me and work in a hospital with windows that do not open, get outside to take walks throughout the day. CO2 monitors available here if you’re curious.