Stringent social distancing measures and building cleaning efforts to protect occupants from the coronavirus that causes COVID-19 are in line with research conducted in the University of Oregon’s Biology and the Built Environment Center.

However, there is more to be considered by building owners and operators, beyond disinfecting and encouraging hand-washing and social distancing, says center researcher Patrick Horve, whose focus is on the spread of infections inside hospitals.

The center, founded in 2010 with support from the Alfred P. Sloan Foundation, studies the microbiome inside buildings, where people spend 90 percent or more of their time.

With the global spread of COVID-19, center researchers, along with collaborators in the UO’s Institute for Health and the Built Environment in Portland and the Genome Center of the University of California, Davis, have reviewed how their research applies to COVID-19 and two earlier coronavirus outbreaks: severe acute respiratory syndrome, or SARS, and the Middle East respiratory syndrome, or MERS.

"Reducing our exposure to this new coronavirus is the most important thing we can be doing, and understanding the mediating role of our indoor environment is vital," said Kevin Van Den Wymelenberg, director of the Institute for Health in the Built Environment and co-director of Biology and the Built Environment Center.

"Our own research, along with our ongoing review of studies of indoor mitigation of pathogens, have led us to recommend several relevant and actionable measures that can be considered, especially for businesses and critical infrastructure that must continue to be open to the public,” he said.

The center’s team recommends:

• Disinfecting surfaces, especially in areas of frequent human contact, with products containing 62 to 71 percent ethanol, a level found in most alcohol-based hand sanitizers.
• Cleaning sinks with alcohol-based products or bleach.
• Removing items from countertops adjacent to sinks to reduce exposure to viral droplets and aerosols.
• Placing reminder signs about hand-washing protocols.
• Making sure soap dispensers are full.

A more-involved series of suggested practices that have emerged from the center’s research include changes to ventilation systems and window operation.

“The big opportunity is with increased access to outside air, which is easiest to accomplish through perimeter windows in many buildings,” Van Den Wymelenberg said. “No common central ventilation filter can reliably eliminate all viral particles because of their tiny sizes — no filter is perfect — but some systems allow increased outside air fractions that can improve indoor air with central ventilation systems.”

Returning exchange rates to normal after viral exposure risks have ended would assure a return to lower energy consumption in normal operation. Some systems, the researchers cautioned, don’t have the capacity for altering outside air ratios. If it is possible, more frequent filter replacements may be necessary. Building managers need to discuss which approach best fits their facilities.

Adjustments to indoor humidity levels are vital in coronavirus cases, Horve said. The research team has found that humidity levels of 40-60 percent may help limit viral survival with little risk of mold growth. However, the team noted, most designs of heating, ventilation and air-conditioning systems don’t allow for central humidification, so targeted in-room humidification may be necessary during episodes of viral risk.

Opening windows to introduce fresh air and opening blinds to admit natural light are simple strategies that can be done in homes and in some workplaces. Opening windows increases the outside air fraction and can help to dilute indoor contaminants.

Exposure to ultraviolet light reduces the ability of some viruses to survive. It is important to note that most UVC light, that with wavelengths between 100-280 nanometers, is eliminated in the atmosphere. Most the ultraviolet lights that produce skin cancers (UVA) and sunburn (UVB) is eliminated through modern glass layers.

While there are ultraviolet electric light sources — UVC and UVGI — that target bacteria and viruses, these must be used in accordance with proper protocols due to detrimental effect to human eyes and skin. The effect on the new coronaviruses is not yet clear.

“Administrators and building operators should encourage blinds and shades to be opened when they are not needed to actively manage glare, privacy or other occupant comfort factors to admit abundant daylight and sunlight,” the researcher noted in written review of lighting strategies.

Caution also is advised for large, open interior spaces, such as rooms of cubicles or other open-concept areas, where there is a high degree of spatial connectivity and more opportunity for social encounter designed into the plan. Increased outside air fraction and social distancing measures are recommended.

“Understanding these spatial concepts could be part of the decision-making process of whether to implement social distance measures, to what extent to limit occupant density and for how long to implement the measures,” the researchers wrote.

Other researchers who were part of the team with Horve and Van Den Wymelenberg were Leslie Dietz of the Biology and the Built Environment Center, David Coil of the University of California, Davis and Mark Fretz of both the Biology and the Built Environment Center and the UO’s Institute for Health and the Built Environment in Portland.

—By Jim Barlow, University Communications