Source Acknowledgements or Sources:

ASHRAE – https://www.ashrae.org/technical-resources/filtration-disinfection

EPA – https://www.epa.gov/coronavirus/air-cleaners-hvac-filters-and-coronavirus-covid-19

CDC – https://www.cdc.gov/coronavirus/2019-ncov/community/ventilation.html

USA TODAY – R. Padilla updated Oct. 19, 2020