Science Inventory

Large-Scale Evaluation of Microorganism Inactivation by Bipolar Ionization and Photocatalytic Devices

Citation:

Ratliff, K., L. Oudejans, J. Archer, W. Calfee, J. Gilberry, D. Hook, W. Schoppman, R. Yaga, L. Brooks, AND S. Ryan. Large-Scale Evaluation of Microorganism Inactivation by Bipolar Ionization and Photocatalytic Devices. BUILDING AND ENVIRONMENT. Elsevier Science Ltd, New York, NY, 227(1):109804, (2023). https://doi.org/10.1016/j.buildenv.2022.109804

Impact/Purpose:

This manuscript describes research to evaluate the efficacy of bipolar ionization and photocatalytic devices against bioaerosols and will be submitted to Building and Environment.

Description:

The COVID-19 pandemic has raised awareness in the spread of disease via airborne transmission. As a result, there has been increasing interest in technologies that claim to reduce concentrations of airborne pathogens in indoor environments. The efficacy of many of these emerging technologies is not fully understood, and the testing that has been done is often conducted at a small scale and not representative of applied settings. There is currently no standard test method for evaluating air treatment technologies, making it difficult to compare results across studies or technology types. Here, a standardized testing approach in a large-scale test chamber with a mock recirculating heating, ventilation, and air conditioning (HVAC) system was used to evaluate the efficacy of bipolar ionization and photocatalytic devices against the non-enveloped bacteriophage MS2 in the air and on surfaces. Statistically significant differences between replicate sets of technology tests and control tests (without technologies active) are apparent after one hour, ranging to a maximum of 0.88 log10 reduction for the bipolar ionization tests and 1.8 log10 reduction for the photocatalytic device tests. It should be noted that ozone concentrations were elevated above background concentrations in the test chamber during the photocatalytic device testing. No significant differences were observed between control and technology tests in terms of the amount of MS2 deposited or inactivated on surfaces during testing. A standardized, large-scale testing approach, with replicate testing and time-matched control conditions, is necessary for contextualizing laboratory efficacy results, translating them to real-world conditions, and for facilitating technology comparisons.