Two recent studies conducted by investigators from the Mayo Clinic demonstrate that high-efficiency particulate air (HEPA) filters are able to effectively filter COVID-19 aerosol particles produced during vigorous exercise and can also decrease the time needed to clean air between patients undergoing stress tests.
Results from the study were published in the journal Chest.
“Our work was conducted with the support of Mayo Cardiovascular Medicine leadership who recognized right at the start of the pandemic that special measures would be required to protect patients and staff from COVID-19 while continuing to provide quality cardiovascular care to all who needed it,” Thomas Allison, senior author on the study said. “Since there was no reliable guidance on how to do this, we put a research team together to find answers through scientific testing and data. We are happy to now share our findings with everyone around the world.”
For the first study, the team of investigators set up an aerosol lab inside of a plastic tent with a controlled flow of air. To measure the concentration of aerosols of someone riding an exercise bike, 2 types of laser beam particle counters were used.
The study involved 8 participants who rode the exercise bike and had their oxygen consumption, ventilation and heart rate measured.
Each participant rode the bike for 5 minutes, followed by a rest and then 4 bouts of 3 minutes at 25%, 50%, 75% and 100% of their age-predicted heart rate.
Findings from the study showed that aerosols increased exponentially after a 50% heart rate was achieved.
The second study employed a HEPA filter to try and mitigate the generated aerosols.
“We translated CDC (Centers for Disease Control and Prevention) guidelines for aerosol mitigation with enhanced airflow through HEPA filters and showed that it worked amazingly well for exercise testing,” Allison said. “We found that 96% plus or minus 2% of aerosols of all sizes generated during heavy exercise were removed from the air by the HEPA filter. As a result, we have been able to return to our practice of performing up to 100 stress tests per day without any recorded transmission of COVID in our exercise testing laboratories.”