COVID-19 has taught us a lot of things. And one of the more important lessons has been the need for thorough, fast and effective disinfecting measures.

A team of researchers from the USF College of Public Health’s (COPH) Center for Environmental/Occupational Risk Analysis and Management set out to determine how effective commercially available chlorine dioxide (CD) gas products were in reducing COVID-19 viral loads on face masks and surfaces.  Their findings, “Virucidal Activity of Chlorine Dioxide Gas for Reduction of Coronavirus on Surfaces and PPE,” was published in February in the journal Occupational Diseases and Environmental Medicine.

To test the efficacy of CD, the researchers—including Drs. Marie Bourgeois, Jeffrey Driver and Raymond Harbison—placed a COVID-contaminated N95 face mask in a plastic bag with a CD sachet. They then tested how much virus was left after 13 hours, 14 days and 30 days. All three times, the CD reduced the viral load by 99.9 percent compared to a control. 

In another test, the researchers set off two CD gas-releasing pods in a closed 1,300-plus square foot room where surfaces had been contaminated with the coronavirus. After one hour, there was a 99.91 percent reduction in the virus versus a non-treated control. After two hours, there was a 99.997 percent reduction.

“This work demonstrates that chlorine dioxide gas can be an effective disinfectant [allowing for] little to no exposure and rapid degradation of residuals,” Harbison said. “Relatively short fumigation of enclosed spaces, such as patient rooms, classrooms and inside ambulances and emergency vehicles, would allow for fast sterilization with less manual labor required of the cleaning staff. What’s more,” Harbison added, “chlorine dioxide is a gas and has the advantage of reaching places liquid disinfectants cannot, providing better efficacy for eliminating the virus.”

Story by Donna Campisano, USF College of Public Health