guidance

In response to the COVID-19 pandemic, many organizations have recommended improved ventilation to reduce the risk of indoor airborne infectious disease transmission. These recommendations include increasing outdoor air rates and filtration efficiencies, as well as verifying that ventilation systems are operating as intended. There have also been many recommendations to monitor indoor CO2 concentrations as indicators of ventilation or infection risk, in some cases with quantitative concentration limits.

ASHRAE’s 2022 publication of a new position document on indoor carbon dioxide (CO2) has been a significant contribution to ongoing discussions of how indoor CO2 can be used to understand ventilation and indoor air quality (IAQ). The position document clarifies what is known about the relationship between CO2 concentrations and ventilation rates, the effects of CO2 on building occupants, and how CO2 concentrations relate to airborne infectious disease transmission. While the position document is a key step to addressing ongoing debate and