The concentration of carbon dioxide (CO2) in an indoor space provides a good indicator of how effectively outdoor air ventilation is being provided. Since cafeterias have the largest concentration of students and staff in school buildings, they provide the highest natural levels of CO2 and serve as a good measure of the effectiveness of outdoor air ventilation as an additional COVID-19 mitigation strategy.
Generally, the risks associated with elevated levels of CO2 in school buildings are very low and would only result in health risks if concentration levels became significantly elevated.
It is important to note that carbon dioxide (CO2) is a gas that is generated by humans when they exhale. It is not to be confused with carbon monoxide (CO).