PCO Technology combines UV light with titanium oxide-coated materials to create hydroxyl radicals and ions known as superoxides. These reactive electrons combine with VOCs, bacteria, and airborne contaminations to break down pollutants into harmless molecules. The nanoparticle science of PCO is widely effective in reducing airborne allergens and contaminants such as mold spores, fungi, dust mites, and other pathogenic microorganisms. PCO Technology is commonly known to be a safe air purification technology as it does not produce ozone or emit harmful substances. In the Aerus Guardian Angel, LED UV lights are combined with a titanium dioxide coating applied to the interior of the HEPA filter cartridge. The resulting PCO process assists the Guardian Angel in reducing common harmful airborne contaminants.