A Closer Look At Ultraviolet Light

Barb Checket-Hanks' recent article, "The ABCs of UV Light" (March 21, 2005), incorrectly reports that "UVV is one of the best weapons in the arsenal against poor IAQ." The article notes that [Sanuvox president Normand Brais, Ph.D., said], "both UV wavelengths [UVC and UVV] attack microorganisms, chemicals, and odors on a molecular level." While this may be true, it is important for your readers to understand that UVV (unlike UVC) will also "attack" occupants in treated spaces by adversely affecting human lungs!

The reason for this is that the shorter (185 nanometers) wavelength of UVV light actually generates ozone. This occurs because UVV light reacts with oxygen to break it into atomic oxygen, a highly unstable atom that combines with oxygen to form O3 (ozone).

The American Lung Association states that "exposure to ozone causes a variety of adverse health effects, even at levels below the current standard." The U.S. Food & Drug Administration says: "In order for ozone to be effective as a germicide, it must be present in a concentration far greater than that which can be safely tolerated by man and animals." The longer (254 nanometers) wavelength of UVC light, by contrast, provides highly effective air, surface, and water disinfection without producing any harmful ozone.

The materials and methods of UV lamp construction determine whether a given UV device will produce both UVC and UVV light or only the safer UVC wavelength. Contractors who embrace the notion that UVV is a performance-enhancing feature may be in for an unpleasant surprise.

Robert Scheir, Ph.D., President
Steril-Aire Inc.
Burbank, Calif.

Responding To Concerns About UVV Light

Allow me clarify a few points regarding Steril-Aire's letter [above]. Steril-Aire is absolutely right in the health concerns regarding elevated ozone levels associated with ozone generation in high levels or when used as a germicide.

As was discussed in Barb Checket-Hanks' article ["The ABCs of UV Light"], Sanuvox UV air purifiers use a UVC-UVV lamp to destroy biological and chemical contaminants in the air. The germicidal portion of the proprietary lamp (254 nm), the wavelength that destroys biological contaminants, is more than 90 percent of the total lamp glass. Sanuvox does not use ozone as a germicide.

Mr. Scheir's statement, that "In order for ozone to be effective as a germicide, it must be present in a concentration far greater than that which can be safely tolerated by man and animals," does not apply to the Sanuvox process; it was clearly stated in the article that Sanuvox uses UVC as the germicide.

As part of the proprietary Sanuvox process involved in UV air treatment, the UVV (187-nm) portion of the lamp is fused to the UVC (254-nm) portion of the glass. Sanuvox lamps are not ozone generators; ozone is a byproduct of oxidation. As the oxidation is emitted from the UVV portion of the lamp, the UVC wavelength immediately starts to break down residual ozone that may be present. Sanuvox is treating the chemical contaminants in the air at that moment in time; this is one of the components of the Sanuvox U.S. patent.

The amount of residual ozone produced by a Sanuvox UV air purifier with the UVC-UVV J lamp has been measured by independent accredited testing laboratories and found not to exceed 0.0035 parts per million at the outlet of the purifier. This is less than 1/10 of the ASHRAE [American Society of Heating, Refrigerating, and Air-Conditioning Engineers] limit (0.05 ppm) and less than 1/20th of the OSHA [Occupational Safety & Health Administration] (0.10 ppm) standards for safe ozone levels.

In fact, the UV process produces less residual ozone than a photocopier or the arcing from an electronic air cleaner, and in documented air quality tests, zero ozone levels have been found in the living or working area.

For this reason, it is important to note that UVV (oxidation) is one of the best weapons against poor IAQ. Thousands upon thousands of building occupants have benefited from UVV oxidation because, without it, it would be impossible to treat chemical contaminants such as VOCs, formaldehyde, diesel fumes, solvents, and cigarette smoke on a molecular level, be-cause the UVC wavelength is ineffective against such contaminants.

Although I commend Steril-Aire for bringing this issue to your readers' attention, it is important to understand how specific UV wavelengths are used, for what purposes, and in what concentrations.

Aaron Engel, Marketing & Communications Director

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Publication date: 04/11/2005