Lawrence Berkeley National Laboratory, or Berkeley Lab, researchers identified indoor air-filtration strategies to mitigate the spread of infectious airborne diseases in the hopes of reducing super-spreading events and outbreaks in congregate public spaces.

Researchers utilized computer simulations to analyze various indoor engineering systems such as ventilation, exhaustion, filtration and disinfection, according to a campus press release. The research identified the need to invest in and implement building controls in real-world settings in order to further investigate factors such as comfortability, operational challenges and energy costs.

The research focused on “simple” cases of buildings that used heating, ventilation and air conditioning, or HVAC, ventilation and filtration as the main engineering controls, according to Berkeley Lab’s Indoor Group postdoctoral researcher Jacob Bueno de Mesquita.

“Many have talked about the idea of layered airborne viral protections, and also the hierarchy of controls,” Bueno de Mesquita said in an email. “This means that it is happening ‘behind the scenes’ and is making the indoor spaces in the building safer for human interaction.”

Bueno de Mesquita also noted that air cleaning is very much relevant in multiple settings, such as school classrooms, gymnasiums and dorm rooms — especially considering these are “high risk settings” where spreading is most likely to occur.

When it comes to the classrooms on campus, HVAC systems have been implemented where “feasible” and building filters have been upgraded to “highest efficiency,”  according to Office of Environment, Health & Safety assistant manager Patrick Kaulback. 

Sally McGarrahan, assistant vice chancellor for facilities services, added that efforts have been made to maximize classroom ventilation with outside air when possible. In most cases, if the instructor is concerned about problematic ventilation, they can report it, she noted.

Campus took further precautions after the COVID-19 pandemic and the return to in-person learning this semester, according to Kaulback.

Kaulback said in an email that California OSHA guidelines required the campus to “maximize ventilation and filtration” as possible.

Both Kaulback and the researchers added that controls such as ventilation and filtration are implemented with other precautionary measures against infectious diseases such as COVID-19 or influenza, including vaccinations, face masks, outdoor gatherings and social distancing.

Bueno de Mesquita noted that these engineering solutions to air cleaning add to a “package” of strategies that can be used individually or together.

“In general, water is treated before reaching the faucet and food is tested and inspected for safety, but there are no health standards for indoor air quality, despite a predominant airborne transmission mode for SARS-CoV-2, influenza and other respiratory infections,” Mesquita said in the email.  “If societies want to get to a place where they can avoid social lockdowns when new variants arise or other infectious diseases emerge, or during annual influenza epidemics, then air cleaning clearly supports this mission.”