FAQ about IAQ and UVC


Indoor Air Quality and UVC
	NEW What about other new products being advertised as providing improved Indoor Air Quality? How can I tell that indoor air is contaminated? What causes the "dirty sock" smell in air handling systems? Why aren't air filters good enough? What is ultraviolet light? What is UVC? What is UVGI? What other methods (beside UVC) are used for cleaning inside air handling units? Where should the lights be installed? How often do the UVC lights need to be changed? How much energy does a UVC device use? Is ozone an air purifier or a contaminant? Is there any research on the effect of UVC on eliminating or preventing SARS?

	What about other new products being advertised as providing improved Indoor Air Quality? Here are some examples we have seen or heard advertised recently and a little background about each of them: Activated Oxygen is ozone. The Federal Drug Administration (FDA) has determined that ozone to be effective as a bactericide or deodorizer must be present in greater amounts than can be safely tolerated by people or animals. Photo Catalytic Oxidation (PCO) is a proven technology, but the amount of catalyst necessary to be effective at 50% oxidation is about 50 square feet of surface area. Cold Plasma System produces "singlet oxygen." This is a single, unstable molecule that seeks to attach itself to another element. When a single molecule of oxygen combines with normal oxygen is produced. Ion Generators (PCO) use a proven technology but are typically used in a room air purifier, which only treats the air in one area. More importantly, they do not impact microbial growth in the dark, damp environment of the air conditioning system. Top How can I tell that indoor air is contaminated? Sniff the air. The nose is the best odor and gas detector, and a good particle detector as well, especially when first entering a contaminated environment. Unfortunately, in as little as 15 minutes, it adapts to the environment and stops detecting contaminants. Chronic respiratory distress, headaches, and fatigue may also be signs of contaminated air. Top What causes the "dirty sock" smell in air handling systems? The cause of the problem is the growth of mold and bacteria in the drain pan and on the coils. Popular, energy-saving heat pumps are particularly susceptible to this syndrome because their heating cycles are not hot enough to kill the microbes that multiply during the cooling cycle and when the unit is idle. The smell comes from the rich brew of microorganisms that breed on the cooling coil and in the drain pan water. The slow warming of this contaminated water releases a plethora of spores and toxins -- and the nasty smell -- into the air. Top Why aren't air filters good enough? Air filters, including High Efficiency Particulate Air (HEPA) filters have been used for many years in heating, ventilating, and air conditioning (HVAC) systems. Some are very effective in trapping particles like pollen and dust. Unfortunately most do not trap minute particles like viruses, most bacteria, and mold spores that breed in the dark moist interiors of HVAC cooling coils and drain pans, which are located downstream of filters. Regardless of the type of filter used, it is critical that all filters be sealed on all edges and joints to prevent the bypass of particles. There is also a problem with fungal spores growing and multiplying in damp HEPA filter material. When this happens, the filter can actually increase the number of spores in the room or the building. Ultraviolet germicidal devices radiate powerful UVC light onto the coils and drainpans inside the air-conditioning system where mold and other odor and disease causing organisms breed. The UVC light inactivates and gradually vaporizes this microbial growth, removing it from the air, thus accomplishing what the air filter cannot do. What is ultraviolet light? Ultraviolet light represents a portion of the sun's electromagnetic spectrum. It is the wavelength band immediately beyond the violet end of visible light. The UV range of the spectrum is characterized by wavelengths between 100 and 400 nanometers (nm). It includes the long-wave UV-A (315 to 400 nm), which causes suntan (or burn), medium-wave UV-B, (280 to 315 nm) used to treat skin conditions such as psoriasis, and short-wave UV-C (200 to 280 nm). Top What is UVC? Short-wave ultraviolet radiation, in the "C" band of 200 to 280 nanometers, has been used in a wide range of germicidal applications since the late 1800s to destroy bacteria, mold, yeast, and viruses. UV-C, or UVC, is often referred to as germicidal UV. What is UVGI? The commonly used acronym UVGI refers to ultraviolet germicidal irradiation, which is the same as UVC. What other methods (beside UVC) are used for cleaning inside air handling units? Coils are cleaned with various combinations of detergents, solvents, biocides, foaming cleaners, and high pressure hot-water sprayers. When cleaning is neglected, the build-up of mold inside the coils becomes very difficult to remove. Chemical cleaning of HVAC equipment is time consuming. It must be done properly to be effective, and it must be done regularly since contamination returns as the chemicals wear off. The toxic chemicals present health issues for the workers doing the cleaning, as well as for building occupants. And some chemicals cause corrosion to the metallic surfaces, shortening the life of the equipment. Pressure washing of the coils may force mold and particulate deeper inside, further restricting the air flow. When this happens, it becomes virtually impossible to physically clean the coil. UVC lights by contrast effectively "zap" mold and other microbes. As the organisms disappear, UVC rays penetrate farther into the coil until all particles and volatile organic compounds (VOCs) have been vaporized. Top Where should the lights be installed? IAQ - Energy Solutions offers a wide variety of UVC devices that can be adapted for virtually any system or application. In general, though, the light is installed on the discharge side of the cooling coil and mounted so as to expose both the coil surface and the drain pan to as much light as possible. The light is normally positioned about a foot from the coil surface. Top Is one light enough? One is enough for most residential installations. Normally the number of lights can be based on one light for each 5 square feet of coil. The most important consideration is that UVC be installed so that there is a "line of sight" between the UVC lamp and the entire coil surface. How often do the UVC lamps need to be changed? The actual life of a UVC light is 10 - 12,000 hours. The useful life is 8-9,000 hours. UV output is measured with a radiometer. Typically the light is changed annually -- ideally in spring or early summer to provide optimal output during the peak air-conditioning season. How much energy does a UVC device use? Each unit consumes very little energy. Normally the energy cost to power each fixture is under $.12 per day. Top Is ozone an air purifier or a contaminant? Ozone is being marketed by some as an air purifier, often in conjunction with UVC. It is true that UVC will produce ozone at low frequencies. The UVC devices that IAQ - Energy Solutions handles attenuate all frequencies below 200 nanometers so that no ozone is produced. According to the U.S. Food and Drug Administration: "Ozone, to be effective as a bactericide or deodorizer, must be present in concentrations far greater than that which can be safely tolerated by man or other animals." According to the U.S. Environmental Protection Agency, oxone is a toxic gas with vastly different chemical and toxicological properties than oxygen. When inhaled it can damage the lungs, and relatively low amounts can cause chest pain, coughing, shortness of breath, and throat irritation. Ozone has been used effectively for years to clean waste water. In water containing organic material, ozone is used up rapidly -- before it reaches the air. Top Is there any research on the effect of UVC on eliminating or preventing SARS? We are not aware of any research that has been done on this pathogen. However extensive testing has been done over the years that proves the effectiveness of germicidal UV (UVC) against a variety of infectious organisms. There is also a wealth of of anecdotal evidence of significant reductions in infection rates in occupied spaces when using UVC in air-handling systems. We know of several scientific studies that document the effectiveness of UVC on fungal and bacterial contaminants. Since SARS is a virus and viral particles are very small (normally between .75 to .01 micron diameter), much smaller than fungal or bacterial particles, they should be much more suseptible to UVC energy, even when attached to droplet nuclei, as in a sneeze or cough. SARS is thought to be spread by direct contact and by inhalation. UVC lights in an air-handling system would eliminate only the airborne particles. Even so, properly designed and installed UVC light systems will reduce the overall numbers of pathogens and provide a significant amount of protection. Top
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