By: Meteorologist Michael Karow
Updated: Jun 26th 2023

Carbon Dioxide and the Indoor Environment

From global warming, to rising sea level, to ocean acidification, these are just some of the well-documented consequences if carbon dioxide (CO
2) levels in the atmosphere are allowed to continue on their current trajectory, through the end of this century. However, the impact of these consequences on everyday life might seem unclear, owing to their global scale. One direct consequence of rising CO2 levels, which could impact daily life, even inside homes and other buildings, is cognitive impairment. A 2020 study by researchers at the University of Colorado Boulder and University of Pennsylvania sheds light on the indoor challenges that rising CO
2 levels may pose by the year 2100.

As measured at Hawaii’s Mauna Loa Observatory since 1958, atmospheric CO2 levels have steadily risen from 316 parts per million to the current level of 424 ppm. According to the Intergovernmental Panel on Climate Change, atmospheric CO2 levels could reach 930 ppm by 2100. Furthermore, the estimate of 930 ppm is averaged for the whole “outdoor” atmosphere. Locations in urban areas tend to have higher average CO2 concentration than in non-urban areas. In addition, the indoor air we breathe can have significantly higher CO2 concentration, such as in rooms with poor ventilation, or rooms crowded with many people.

By century’s end, CO
2 levels in the average indoor space could approach 1400 ppm. According to this study, levels that high are capable of impairing peoples’ decision-making skills by 25%, and their complex strategic thinking ability by 50%. Although there may be ways to adapt indoor spaces and ventilation systems to help overcome some of this increase in indoor CO
2, some of these adaptations may involve increased CO
2 emissions to the outside, too. Decreasing overall CO
2 emissions in the upcoming decades still appears to be the most surefire way to prevent not only indoor air quality issues, but the remainder of negative global impacts caused by this greenhouse gas.