Clean, breathable air is something that all of us should have access to in our own homes. Unfortunately, this is not guaranteed, even if you have an air filter in your HVAC (heating and air conditioning) system. Air filters trap contaminants so that they cannot continue to circulate in your home. However, the standard air filter can only remove particles 10 micrometers in size or greater. And some of the worst contaminants are much smaller than this.