You can get a whole-house air cleaner if you have an existing duct system, even without an HVAC system. Most typical whole-house air cleaners work by attaching them somewhere on your HVAC system to clean the air that flows out of ducts into your home. If you don’t have an HVAC but have a duct system, you can get a whole-house stand-alone air purifier that attaches to your duct system.