Of course, one of the first line therapies in the treatment of allergies and asthma is the avoidance of offending allergens. Airborne allergens in the home constitute one of the hardest types of allergens to avoid. Heating and air conditioning systems have been established as harbors for molds, and certainly with vents in every room this same system is an efficient distribution system. So certainly the "sanitation" of this system is of great interest to allergic and asthmatic patients.

To test the theory that commercial air duct sanitation is effective in reducing indoor allergen levels, eight residential "heat-ventilation-air conditioning" (HVAC) systems in six homes during winter (heating mode); and six HVAC systems in five homes during summer (cooling mode); were sampled to measure fungal "colony forming units" (CFUs). The sampling was done before and after HVAC sanitation occurred. Two homes in which no duct cleaning was done served as controls in each phase of this study. The homes ranged in size from 1,500 sq. ft. up to 4,600 sq. ft., and all were of brick or brick and wood frame construction. The study took place in north Texas.

Sampling was performed using culture plates of malt extract, which provides an excellent growth medium for fungal colonies. The plates were placed directly in the air stream.

The baseline CFUs were found to be approximately equal in the control and study homes. Eight weeks after the sanitation procedure, the study houses exhibited a whopping 92% decrease in CFUs during the winter, and an 84% reduction in the summer. Over the same 8 week period no reduction in CFUs was observed in the control houses.

This indicates dramatically that air duct cleaning by a qualfied commercial firm does indeed provide relief from airborne molds, one of the most common aeroallergens. This benefit can be extended by installing a high efficiency intake filter following such air duct cleaning.

Another interesting fact the researchers noted was that pre-cleaning CFU levels were much higher in the summer than in the winter. They speculate that this could be due to the fact that in a cooling mode, there is higher moisture content due to the evaporative coils.

Do UV Lights Really Work

Many of the things we do to make our homes energy efficient -- such as adding insulation, installing new windows, even caulking -- save money on fuel bills but make our homes less healthy places in which to live. Sealing out drafts also seals out healthy fresh air and traps moist air, laden with household gases, inside. This moist, stagnant air is unhealthy to breathe and provides excellent breeding conditions for mold and other microorganisms.

The American Lung Association often sites U.S. Environmental Protection Agency statistics that the air we breathe in our homes may be anywhere from two to 100 times more polluted than outside air.

David Mudarri of the EPA's Indoor Environments Division believes that about 40 percent of us suffer effects ranging from dry eyes and sniffles to severe asthma attacks every week. His views and those of other experts appeared in an excellent article, "Indoor Air Pollution Can Cause a Sick Home," by Joysa Winters of the Rocky Mountain News. The complete text is available on the Indoor Air Quality News page of the International Union of Operating Engineers IAQ web site (http://iaq.iuoe.org/index.htm).

As consumers, there is a lot we can do to make the air in our homes cleaner. Air infiltration devices can bring fresh air into the house. Thick media filters and electronic air cleaners can clean the air, but they miss some of the finest particles. Cleaning and sanitizing the ductwork can cut down on dust and mold. Clean air legislation is making paints and chemicals more benign than their predecessors.

Now ultraviolet light has been added to the arsenal. The greatest source of UV is the sun. Its rays bleach furniture and fabrics and turn wooden decks gray. We use sunscreens, sunglasses and hats to protect our skin and eyes from its power.

UV waves are even more dangerous to molds and bacteria. They penetrate cell walls and change the organisms' DNA, making cell reproduction impossible.

Technology using UV has been available commercially for 40 years but has only been introduced on the residential level recently.

Not all UV lights are created equal. Some create ozone. Some do not. Ozone is an unstable O3 molecule. Many people consider ozone a side benefit because it zaps contaminants in the air. Connie Morbach of Sanit-Air is a licensed ozone technologist and is ultra conservative when it comes to ozone use.

"Some people are very sensitive to ozone. If there is enough ozone in the air to give a diluted bleach smell, the homeowner could experience unhealthy side effects," Morbach says.

"Levels of fungi growing on insulation within air-handling units in an office building and levels of airborne fungi within AHUs were measured before the use of germicidal UV lights and again after 4 months of operation. The fungal levels following UV operation were significantly lower than the levels in control AHUs" - Study from The University of Tusa, Tulsa, Okahoma.

If you want to improve your home's air quality, there may be a UV light at the end of the tunnel. It could help you breathe a lot easier.