The traditional furnace air filter isn't designed to clean air much at all. Its only function is to keep large particles like hair and debris from damaging the furnace blower. These large particles are rarely the source of human breathing difficulty.

The main advantage of traditional filters is that they provide low-cost protection to the heating and cooling equipment. But beware, if you don't change these furnace filters every month or two, they will become clogged and eventually drastically reduce your furnace's air supply. At the very least, clogged filters will make your furnace work harder and waste energy. At worse, it will cause "cycling," which can ruin the blower motor.

Cycling occurs when your furnace overheats. The furnace is equipped with a safety feature which automatically shuts it off when it gets too hot. Typically, overheating occurs when the furnace doesn't get enough air flow. Air flow can be hindered by a dirty filter or by furniture blocking return registers. After the furnace cools somewhat, it automatically turns back on. A minute or so later, it overheats and cuts off again. This on-and-off cycling is very hard on the motor. It will also usually limit the furnace's ability to heat the house on especially cold days.

While traditional filters cost less than $2, there are many fancier filters on the market today that filter out enough particulate matter to help humans breathe better. In general, the more costly the filter, the more dust it snags out of the airstream. Costing anywhere from $7 to $100, sophisticated filters can pull out up to five times as much dust as a traditional filter.

Whenever you try a new filter, make sure your furnace doesn't start cycling. After installing the new filter, turn the furnace on and listen carefully. If it cuts off after a few minutes and it does so before the house has reached the temperature you indicated on the thermostat, you may have a problem. If the pattern repeats, check to see if the return air registers around the house are obstructed. If the registers are clear but the furnace keeps cycling, switch back to your original filters.

If you aren't ready to settle for dirty air, ask a professional if your furnace can be modified to accommodate better filters or consider installing an electronic air cleaner. The more advanced the filter, the smaller the particles of dust it can trap. Household dust typically includes large quantities of hair, skin and pollen. It also includes lots of dust mites.

Dust mites are microscopic bugs that look like a cross between Godzilla and a tick -- nasty critters -- and the typical home has millions of them. Fortunately, they are too small to see with the naked eye. If you could see them, you'd probably feel compelled to move out. While the dust mites can be very irritating to the lungs, their dung and carcasses can be even worse.

Generally, the better the air filtering or cleaning system, the more dust mites and dust mite debris that is filtered out of the air. The most impressive filters use electrostatic energy to help capture about 5 times as many particles as a traditional filter. These filters have plastic or metal strips that generate static electricity when the air blows over them. In turn, the static electricity attracts very tiny particles.

As with the basic filter, it is important to change all filters regularly. Some filters are reusable. With these, take them outside and hose them down once every month or two. In the winter, use a deep laundry sink. Many people buy these filters thinking they will save money. But, after cleaning them a couple of times, they decide it's too much bother and switch back to disposables. The choice is yours, but make sure you don't allow dirty filters to stay in your furnace.

Electronic air cleaners, which can extract 30 times as much dust as ordinary filters, cost a lot more. In fact, a professionally installed air cleaner costs $500 to $700, including installation.

While this is a substantial amount of money, it's worth every penny if it offers significant breathing relief to one or more people in your household. But, if the price is too steep for you, portable units can be purchased for far less. Of course, the smaller units clean just the air in one room - much like a window air conditioner cools only one room.

Electronic air cleaners only need to be cleaned once a year or so because they incinerate the trapped dust. The human body is well equipped to handle breathing dirty air, so most people have no problem breathing normal household air - dust mites and all. But if someone in your household suffers from asthma, chronic bronchitis, emphysema, allergies or other respiratory problems, you should investigate ways to make the air in your home more breathable.

Because electronic air cleaners work silently, the only way to tell if they are working is to introduce some dust or salt to them. If they crackle and pop like a bug zapper, they are working. If not, the filter may have been damaged while cleaning or there could be an electrical problem. In either case a professional should come out and take a look.

-- Tips courtesy of HomeAdvisor.com