Two of us in the house have mild asthma. To make sure we don't get lots of dust mites etc I regularly hang up all bedding and blast it with steam from my steam cleaner. Spraying the room with steam when you've cleaned helps to settle any dust you've disturbed but not managed to remove!
A steam cleaner is also great for easily cleaning floors, sinks, work surfaces etc - I'm not house proud I just like things that make my life easier
