Researchers around the world are seeking to understand the behaviour of the SARS CoV-2 (COVID-19) virus responsible for the global pandemic. University of Alberta researcher Dr. Lexuan Zhong and her team are examining how the virus is transmitted through airborne fine particles, and how its movement is controlled by current heating, ventilation and air conditioning (HVAC) designs within buildings.
“We’ve seen a lot of evidence to show SARS-CoV-2 can suspend in the air for a longer term, including outdoor samples in Italy. If evidence of contamination was found outdoors, we thought indoors must be even more concentrated,” says Zhong, a professor in the Department of Mechanical Engineering. “So what my research will address is, can updating the design of HVAC systems reduce the risks of airborne transmission within a confined space?”
Her team is also determining the size of transmittable airborne fine particles and how they might pass through current HVAC filtration, transporting into other spaces.
“It seems there are more and more cases linked to airborne transmission of the virus which may accumulate or spread over longer distances in closed spaces, so we need to figure out if six feet is enough for social distancing or additional engineering measures are needed.”
Making buildings safer
Alberta Innovates is co-funding this research project with its partner the Canadian Institutes of Health Research (CIHR). The $444,000 grant will go towards purchasing specialized equipment and providing financial support for two PhD students to do experimental and modeling work.
“We are excited to partner with Dr. Zhong on this project,” says Tim Murphy, Vice President of Health Innovations at Alberta Innovates. “The work that Dr. Zhong is engaged in will help inform building operators and the construction industry, ultimately making our homes and businesses safer and help advance decisions around re-opening.”
At its outset, the virus is believed to have been transmitted via the air conditioning system within a restaurant in Wuhan, China, infecting members of an extended family travelling from different areas. The U of A researchers are looking at this case and other recent research pointing to evidence the SARS-CoV-2 virus can indeed exist in an airborne state. Zhong’s project is also exploring current HVAC filtration methods including frequency of filter changes, the type of filter used and other measures like installing advanced air purification systems.
Understanding airborne spread
As well, the U of A team is looking at what size of particles remain airborne after passing through filters. A recent publication in the journal “Nature” reported the SARS-Cov-2 RNA virus existed in droplets as small as 0.25 μm (one quarter- millionth of a metre) when samples were taken in different areas of two Wuhan hospitals during the outbreak in February and March. Current filters vary a lot in their filtration performance, Zhong notes.
Zhong is supported by two co-principal investigators, Dr. Brian Fleck and Dr. Lisa Hartling. Fleck, also an engineering professor, is examining field studies to determine the feasibility of implementing their findings. Hartling is conducting a literature review to determine the advantages and disadvantages of existing technology. The research team is working at a rapid pace, putting in long hours, seven days a week.
“Yes, we are working very hard right now,” Zhong says. “But once we figure out how to improve the operation of HVAC systems, we can immediately reduce human-generated airborne virus in public spaces and create safer indoor environments for occupants, especially those who are in quarantine or in hospitals.”