Iowa State University



ISU Building Ventilation Systems and COVID-19 - UpdateThe potential for airborne transmission by the SARS-CoV-2 virus has been reported in the news. Airborne transmission occurs if the virus remains in the air for a longer period of time and is spread between people more than 6 feet apart. Airborne transmission does not necessarily mean the virus can spread through the central ventilation systems typical of university buildings.The federal Centers for Disease Control and Prevention (CDC) has updated their guidance regarding airborne transmission. The CDC states airborne transmission can occur under special circumstances including enclosed spaces, prolonged exposure (often to people shouting, singing or exercising) and inadequate ventilation. The updated CDC guidance does not recommend special engineering controls, and reiterates the need for physical distancing, face coverings, hand washing, cleaning and disinfection, ventilation, and avoiding crowded indoor spaces. In other guidance the CDC still states that the risk of spreading the virus through building ventilation systems is likely low. Recommendations for operating building ventilation systems from the CDC, World Health Organization, Occupational Safety and Health Administration, and American Society of Heating, Refrigerating and Air-Conditioning Engineers currently include:Ensuring proper system operationIncreasing ventilation rates and the amount of outdoor airMaintaining temperature and humidity at comfortable levels for occupantsImproving air filtrationOperating ventilation systems beyond normal operating hoursNormal maintenance to ensure proper operation of campus building ventilation systems has continued through the fall semester, and will continue over the winter break and spring semester. The outdoor air supply for campus building systems has been checked for proper operation while still maintaining proper indoor temperature and humidity. Ventilation systems are also being run well before and after normal operating hours to flush the air in the buildings.Conditioned air is filtered before being distributed by the ventilation system to individual rooms. The filters provide the improved air filtration recommended for office or academic buildings. While not intended to remove particles as small as a virus, these filters can still remove 65% or more of particles carrying the virus. Ultra-low particulate filters or ultraviolet light disinfection for additional removal would require redesign and reconstruction of the building systems.In response to the reported concern for airborne transmission, before the fall semester Facilities Planning and Management identified campus buildings without adequate ventilation. Classes were not scheduled in the general university classrooms in those buildings, and occupants were notified to use both physical distancing and face coverings for shared use of rooms.The updated CDC guidance states that most infections are spread through close contact, not airborne transmission. The best way to protect from the spread of the virus remains maintaining the recommended physical distance from others, use of face coverings, washing hands frequently, and staying home if one is not feeling well. ................
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