We breath air that contains Oxygen, Nitrogen, Carbon Dioxide, and other compounds. In homes with high Co2 levels the occupants complain of headaches and drowsiness. This adverse condition occurs when the indoor levels of Co2 exceed 1000 PPM, or parts per million. In most cases, the occupants are unaware that their home, place of work, and even their cars may have elevated Co2.
When we exhale, we breathe out more Co2 than we inhale. Tight indoor environments with poor air exchanges and a lack of fresh air may allow Co2 levels to increase. In homes for example, with windows closed and the heat or AC running the Co2 levels with likely rise. In addition, the more individuals in a room, car, or office will increase the Co2 levels due to their exhalation of this gas.
Testing of indoor environments including automobiles have found a correlation between headaches and drowsiness when the CO2 levels exceed 1500 PPM. Most cars for example with the windows closed will have CO2 levels of 2000 PPM. The term "Asleep at the wheel" could be related to this issue.
In a recent study by the University of Colorado at Boulder, they found that when an excess of CO2 levels double, the risk of transmission for viral infections such as COVID-19 also roughly doubles. In these instances, the CO2 acts as a surrogate for COVID-19 and a number of other viruses in the air. It's information is explained in a relatively understandable way: As we're exhaling the CO2, we're also exhaling viruses. An elevated level of CO2 in a structure is also relative to the use of the structure - the chief example in this article states that there is a difference between the elevation in a library vs. a fitness center. Because there is a lot of heavy breathing and exhalation in a fitness center, the risk for viral exposure is increased.
The best remedy in all cases is fresh air. In an office or home, we need additional fresh air exchange and open windows when the weather complies. In a car, open both windows a few inches to allow outside air to enter the cabin and exchange with the indoor environment. This quickly reduces the Co2 levels. Simple measures often result in better health.
University of Colorado at Boulder. (2021, April 7). Carbon dioxide levels reflect COVID-19 risk: Research confirms value of measuring carbon dioxide to estimate infection risk. ScienceDaily. Retrieved May 13, 2021 from www.sciencedaily.com/releases/2021/04/210407143809.htm