ACHRNEWS

UV, UVC Product Makers Study Anthrax Dosages

November 28, 2001
Manufacturers of products that use ultraviolet (UV) and UVC light to aid indoor air quality are reporting on their progress to support claims that the products are effective against anthrax. While many are assumed to be so, studies are still in progress to determine optimal dosage.

Honeywell Control Products stated that “Bacillus anthracis, the bacteria that causes the disease anthrax, can be as small as 1 to 1.25 microns in size. While there is a lot of speculation, it is not currently known what UV dosage would be required to render Bacillus anthracis harmless.”

The company continued, “Honeywell is working diligently to learn more about the anthrax threat and to test both its UV air treatment systems and air cleaners with respect to performance against Bacillus anthracis. But, Honeywell will make no claims relative to protecting consumers against airborne exposure to Bacillus anthracis unless it has adequate substantiation to support such claims.

“Honeywell urges its customers and consumers to approach any claims by others who are selling their products as ‘anthrax killers’ with caution, and ask to see supporting documentation and substantiation before purchasing a product that has been advertised as a solution for Bacillus anthracis.”

Other companies also are taking pains to substantiate their product claims.

Steril-Aire, Inc., explained that “Dating back from the 1940s-80s, major studies by Phillips, Westinghouse, and others have measured the dosages of both sunlight and germicidal UVC energy required to destroy microorganisms of interest. A study issued by Phillips Lighting found that the dosage of ‘UVC’ energy [UV light’s ‘C’ frequency] required to destroy Bacillus anthracis is 4,250 µW-sec/sq cm. Steril-Aire is recommending a much higher dosage starting at 9,000 µW-sec/sq cm plus, depending on the circumstances — for an added margin of safety.”

The company explained that “Because anthrax and other microbes are dangerous to work with, some of the published doses are extrapolations using mock microbes with like mass, density, and color. This is an accepted scientific approach that has been used to develop reliable dosage recommendations for such things as TB and other harmful microbes.

“It is also common knowledge that the ‘less-germicidal’ UV frequencies of ordinary sunlight” — that’s UVA and UVB — “will kill anthrax in a very, very short time. References to this can be found from one of the most active scientists in this area, E. Mitscherlich of Germany (1984), and this year by our own Dr. C.J. Peters, former chief of Special Pathogens at the CDC and now professor of pathology at the University of Texas, Medical Branch in Galveston.

“Together, these facts give us, others, and branches of our government confidence that the much more destructive UVC waveform would have at least the same germicidal effect on Bacillus anthracis.”

In addition, UVC should be used as part of “a total engineering control strategy that should include air filtration, proper ventilation practices, and other proactively preventive measures,” the company said. It does not promote its UVC products as a single solution or “cure” to infectious-type microbial problems.

The company is participating in a specific test with the State of New York, a New York State university, and F.P. Technologies to determine the dose required to kill anthrax. Results will be made available very soon, the company said, and reported in The News.

Both Honeywell and Steril-Aire are warning consumers to carefully evaluate manufacturers’ claims of their products’ ability to kill Bacillus anthracis.

Publication date: 11/26/2001