98% of the particles you breath are below one micron. Regular air filters are not capable of collecting such small particles. But an air cleaner can. The PREMIERONE HP500 HEPA filter can. It's installed on the return air side of the duct, so it provides maximum particle collection while still providing maximum airflow. Superior filtration traps germs, bacteria, viruses and allergens Controls smoke, dust, pollen, and other organic and inorganic particles Insulated cabinet offers quiet operation 2-speed operation for maximum efficiency Easy to maintain Pre-filter with carbon lasts 6 months HEPA filter lasts 2 years