The Photocatalytic Oxidation process combines UVC irradiation with a substance (catalyst) titanium dioxide (TiO2) which results in a reaction that changes malignant contaminants into water, carbon dioxide and detritus. The air purification process of using photocatalytic oxidation often works by using an existing air system that pulls air through an air conditioning unit (HVAC) which passes through the professionally installed ultraviolet light/ titanium dioxide chambers. As the malignant contaminant-filled ambient air circulates through these chambers the microbes are “attacked” by free hydroxy radicals and super-oxide ions (created by UV light and titanium dioxide) breaking their cellular structure apart and destroying both the intracellular mass and DNA/HNA chromosomes. The result is harmless water molecules, carbon dioxide and detritus (see diagram above).
To learn more about photocatalysis, see https://en.wikipedia.org/wiki/Photocatalysis.