(ARA) - It's a common complaint. Just a few days after a thorough house cleaning, that unsightly dust is back, settling on every surface in your house. Dust can also contribute to respiratory allergy suffering. Although the visible dust is most obvious, health scientists now say it is the very small invisible particulates and noxious gases we should be most worried about. What's the answer? Here are seven proven ways to greatly reduce dust and breathe easier in your home.

Identify and Seal Air Leaks That Let In Dirty Air

A good deal of the dust in our homes comes from internal sources such as skin flakes and fabric fibers. However, new research has found that in many homes a significant amount of the dust actually originates from outside the living space. The hot or cold outside air that leaks in through gaps and cracks often brings a lot of dust along with it. The air from outside always contains airborne particles such as mold spores, pollen, soot, tire rubber and agricultural dust.

Building scientists have recently discovered that in the typical home, most of the incoming air first passes through dirty areas such as the attached garage, outside walls, crawlspace, basement, attic or even from underground. This incoming air is often contaminated with pollutants such as mold spores, carbon monoxide, automobile exhaust, carcinogenic radon gas, insulation fibers, pesticides and volatile organic chemicals.

Contact your HVAC contractor and ask for an Infiltrometer blower door test to pinpoint where the bad air leaks are. Many leaks can be easily repaired by homeowners as weekend projects. Others such as leaks in your air ducts, or through recessed can lights are better left to professionals.

Finding and fixing the leaks that let in bad air will make your home healthier, more comfortable and less dusty. Your home will also have more controllable indoor humidity levels. Fixing these air leaks will even pay for itself through lower heating and cooling bills. In fact, duct leakage alone has been found to waste 20 percent to 40 percent of most systems' heating or air conditioning. For more information on Infiltrometer testing and duct leakage, go to www.comfortinstitute.org.

Fix Negative Air Pressure

Many homes operate under what is called "negative air pressure," created unintentionally by the mechanical systems. The air pressure becomes lower in the home than outside. This accelerates the inward flow of potentially dusty outdoor air, and can even back up furnace and water heater chimneys, allowing poisonous carbon monoxide gas into the home. Ask your HVAC contractor to test your home for negative air pressure and proper venting of gas and oil appliances. For a free report on how to identify a good HVAC contractor, go to www.comfortinstitute.org.

Create Positive Pressure with Ventilation Air

While negative air pressure is bad, a slight positive pressure is good. A house at an intentional positive pressure has much less dust. Ask your HVAC contractor for information on how to create positive air pressure. The first step is an Infiltrometer blower door test to determine how leaky your house is, so that the right amount of pressurization airflow can be determined.

Upgrade Your Central Air Filter

Typical throw away furnace filters do not even adequately protect your equipment from getting fouled up, let alone protect you from invisible respirable particles. Ask your HVAC contractor for recommendations on installing a new high efficiency filter at the equipment. One of the best are pleated media filters, typically four to six inches thick, that only need to be changed once a year. Have your HVAC contractor first test the duct system static pressure to ensure your system can handle the increased pressure created by a good filter. On larger 4 and 5 ton AC systems it is often necessary to split the airflow in two and have two filters.

Install a Whole House Central Vacuum Cleaner

Vacuuming helps control dust, but most vacuum cleaners simply don't catch the very small particles. The majority pass right through the filter bag. Although a new vacuum with a "HEPA" filter is good, the best solution is a central vacuum cleaner that exhausts the small particles directly to outside.

Run Your Furnace Fan When Vacuuming

Even the best vacuum cleaner agitates some dust into the air. If your forced-air system is equipped with a good filter, you can filter out some of that dust before it settles by switching your thermostat to "fan on" while vacuuming.

Get Your Duct System Cleaned

Many duct systems contain large amounts of dust and debris. If you get your ducts cleaned, be sure the contractor thoroughly cleans the furnace/air handler and cooling coil as well. Note that if you have dirt accumulating on the supply air vents, the cause is most likely duct leaks in the vicinity, not dirt from inside the ducts. A good sealed duct system, with filtration at the inlets, rarely if ever needs cleaning.

Follow these steps and you can make a big difference in the dust levels in your home. For more free information on HVAC solutions to improving indoor air quality, visit www.comfortinstitute.org and www.epa.gov .