Today's the first day of autumn; you know what that means -- furnace filter time! But before you purchase a replacement, consider your filtration needs. If allergies or respiratory problems aren't a concern, a standard inexpensive filter will do; it will clear the air, catching dust and other airborne particles that can clog things up. You can soup up filtration power a bit, too, with a special spray-on filter treatment or a spritz of two of household dust mop spray. If breathing easier is also your goal, you have many ways to go and things to consider. High-end filters use rating systems; the higher the number, the smaller the particle it filters. Particles are measured in microns. For comparison, a human hair is about 200 pollen, 100 pent dander; dust mites 50 and bacteria fungus smoke and viruses from 5 microns down to a microscopic .002. So, before you buy, decide what and how much you want and need to filter. And that's the On The House Tip for today.