Air conditioning takes humidity out of the air. It reduces dust mites, mold and mildew, which are common allergens that grow best in warm, humid conditions. Standard Mitsubishi A/Cs contain washable filters which captures pet dander and common household odors. Higher end models use an enzyme filter to break down allergen proteins thereby reducing germs, bacteria and viruses, as well as trapping dust, pollens, mites and other particles. We learn more from David Gorman at Revolusun Smart Home.