April 8, 2021

CDC Updates Information on Ventilation in Buildings

CDC has updated its webpage on building ventilation strategies to mitigate occupants’ exposure to and the transmission of SARS-CoV-2. The webpage, which was created to help building owners, operators, and occupants reduce airborne concentrations of viral particles indoors, was amended on March 23 to include simplified language regarding ventilation tools, three new frequently asked questions, and additional information on emerging ventilation technologies and high-efficiency particulate air (HEPA) cleaning units.

The three new FAQs cover the use of carbon dioxide monitors to provide information on ventilation in a given space, the use of indoor temperature and humidity to help control disease transmission, and the use of fans to improve room air mixing. CDC notes that the use of fixed carbon dioxide monitors can be informative in some well-designed and maintained environments, but cautions that limited information exists to show a direct link between carbon dioxide concentrations and risk of COVID-19 transmission. The agency’s FAQ also cautions against adjusting room temperature or humidity as means to control COVID-19. CDC does recommend fans to increase the effectiveness of open windows, provided that users avoid high-speed settings, switch ceiling fans to the reverse-flow direction, and direct fan discharge toward unoccupied areas.

In addition to FAQs, CDC’s ventilation webpage provides a list of tools to improve ventilation. CDC’s ventilation tools are intended to apply across indoor environments, but the practicality of implementation varies across building types, occupancies, intended activities, and environmental and seasonal changes. For more information, see CDC’s website.