In the months since the COVID-19 pandemic arrived across the world, much attention has been placed on how easy it is for the virus to spread in indoor spaces that lack proper ventilation. 

Writing in the academic journal The Conversation, Shelly Miller, professor of mechanical engineering at the University of Colorado Boulder, adds to a growing body of research highlighting the need for a greater degree of interior ventilation in order to help minimize the spread of the disease. Professor Miller writes, "The safest indoor space is one that constantly has lots of outside air replacing the stale air inside," adding, "Many buildings in the U.S., especially schools, do not meet recommended ventilation rates."

Miller recommends that building operators move to increase air exchange rates within interior spaces to nine times per hour, up from the standard six times per hour metric typically used by HVAC engineers. 

Additionally, she recommends installing CO2 detectors indoors to help monitor air exchange rates, making sure that readings stay below the 600 ppm threshold. 

Additionally, Miller recommends indoor air filtration units with HEPA filters be used in cases where boosting HVAC and opening doors and windows for additional ventilation is not possible.