I live in an old house and its constatnly dusty despite vacuming often. Some days I'll wake up and it feels like I can't breathe like asthma (which I had when I was a kid). I though about getting one of those HEPA filters but those things a huge and pretty expensive. So I thought about those ion type filters. A smoker friend has one in his car and claims that it works...and of course these the home versions that are sold through brookstones and sharper images....do they actually work?