10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Evaluation of Ozone Efficiency to Reduce Airborne Virus Concentration in Ventilation Ducts
NATHALIE TURGEON, Jean-Gabriel Turgeon, Jonathan M. Vyskocil, Caroline Duchaine, CRIUCPQ, Université Laval
Abstract Number: 526 Working Group: Infectious Bioaerosol
Abstract Over the last decades, the number of farm have decreased in North America in conjunction with an increase of the number of animal per farm. Disease transmission between animals in the same farm and also between nearby buildings is becoming a major concern in agricultural settings. Several bioconfinement and bioexclusion strategies have been proposed, such as air filtration. However, the installation of air filtration systems are expensive and require tremendous maintenance. Ozone concentration between 2.5 ppm and 3.5 ppm for 14 seconds was shown to be effective to obtain 99% reduction of infectious airborne viruses. However, theses concentrations are too high to be used in agricultural settings. The aim of this study is to design and validate a test duct to use ozone to reduce virus infectivity. Treatment of air in a test duct would allow contact of viruses with ozone without releasing ozone in the building, since ozone is destroyed before air exits the duct.
We assembled a ventilation duct of 220 m long with a 10 cm diameter to test several residence times and ozone concentrations. Air was driven through the duct at 0.6 m/s using an exhaust fan. Relative humidity inside the duct was adjusted to 40% and 80% using a humidifier located at tunnel entry. We used phage PhiX174 as a viral aerosol model. Phage aerosols were generated using a Collison 6-jet and injected into the duct after 150 cm. Aerosols were collected using All-Glass Impingers (AGI-30) after 0 minute residence time (150 cm after injection) as well as 1.5 minute, 3 minutes, and 6 minutes residence times. We tested ozone concentrations between 0.3 ppm and 1.8 ppm as well as residence in the duct without ozone. Air samples were analyzed using plaque assays. PhiX174 plaques obtained with ozone were compared with plaques obtained without ozone for the same residence time to assess the effect of ozone only. Ozone was more efficient at 80% RH compared to 40% RH to reduce PhiX174 plaque detection from air samples. With 6 minutes residence time at 0.3 ppm ozone we obtained 60% PhiX174 plaque reduction under 80% RH and 30% plaque reduction under 40% RH.
This communication describes the use of a test duct to measure ozone efficiency to reduce airborne culturable virus concentration. Reduction up to 60% of phage PhiX174 infectivity was obtained with 6 minutes contact with 0.3 ppm ozone. This technology could be used to test ozone treatment of exhaust air to prevent virus spread in agricultural settings.