The pandemic has brought a new interest from academia into HVAC systems and IAQ. High-profile universities, including Harvard and Purdue, have released studies on how to prevent disease transmission through the air. One such study may provide the ability to take early action in the future to prevent the spread of an array of airborne ailments.
Two professors at East Carolina University in Greenville, North Carolina, worked together on an interdisciplinary project to see if they could detect coronavirus in the HVAC system of the school’s dorms. Sinan Sousan, director of the school’s Aerosol Research Laboratory, oversaw the capture aspect of the project. Rachel Roper, a professor of immunology, handled the testing of the samples. The project was a collaboration between the ECU Department of Public Health, North Carolina Agromedicine Institute, and the ECU Department of Microbiology and Immunology.
The study used various media to collect the samples. These included special filters, sponges, and tubes. The challenge then was getting the samples to the lab intact so they could be checked for coronavirus.
The study did show coronavirus can be detected in an HVAC system. The results were published in the American Journal of Infection Control with title “SARS-CoV-2 Detection in Air Samples from Inside Heating, Ventilation, and Air Conditioning (HVAC) Systems- COVID Surveillance in Student Dorms.” Detecting an airborne virus in a system that moves air seems obvious, but this is one of the first successful attempts to do so.
Hard to Catch
Roper said there have even been samples taken of the air in rooms occupied by COVID patients. These samples wound up testing negative for coronavirus, even though they should have tested positive. She said the key to success for the ECU study was setting up better protocols for collection and testing.
The idea for the study came from other studies that used wastewater samples to detect the presence of coronavirus, such as one conducted at the University of Arizona. These studies did show the virus was present, often to a greater extent than known. But they have their limitations. The wastewater studies were after the fact and only showed the results for a total building, not the specific source of the coronavirus.
“Everything that is flushed down the toilet is literally going down one pipe,” Sousan said.
The ECU study started with a broad sample. Finding the airborne particulates proved challenging. Sousan explains that after they get dispersed, the particulates either land on a surface or the air mingles with air from other sources and the sample sizes decrease. To improve the odds, Sousan, Roper, and their colleagues used data from the random testing performed by the school.
“The closer they were to the collection, the more likely we were to get a positive,” Roper said.
Professor of immunology, East Carolina University
The results of this study could prove very valuable in the future. When cases levels are low, building operators can catch a potential outbreak. They can then send out a message to take preventive measures, such as wearing masks. This could work for a variety of diseases.
“It would be a simple, easy, quick way to really protect people very well,” Roper said.
Sousan said the next step is expanding the study to detect bacteria, such as tuberculosis. Bacteria particles are larger than virus particles, so they will have different travel distances. Virus requires collections closer to source.
There are some more in-depth studies Sousan would like to see done. One is to find out how many particulates a specific infected person sheds so researchers can compare that to how much is captured. Ultimately, it would be useful to know how far the virus can travel through an HVAC system, he said.
“To know this information for future pandemics is very important,” Sousan said.