Inspired by air filtration systems used in hospitals, clean rooms and the aerospace industry, Tesla's HEPA filtration removes 99.97% of airborne particulates, such as smoke, bacteria and pollen. The HEPA filtration system is active whenever climate control is pulling in outside air. For extreme conditions, Bioweapon Defense Mode positively pressurizes your cabin. This prevents pollutants from leaking in as you drive, as all air is filtered through the HEPA and gas media filters. Every new Model Y, S and X comes standard with a HEPA filter and Bioweapon Defense Mode.