Posted on 11/04/2001 11:04:07 PM PST by BlackJack
An indoor air cleaning system originally developed to zap dust mites and mold spores also destroys airborne anthrax and other pathogenic microbes, says the University of Florida engineering professor who pioneered the technology.
The system has been successfully tested against a close cousin of the anthrax bacteria and could be installed relatively inexpensively and quickly in office and home heating and air conditioning systems, says Yogi Goswami, a UF professor of mechanical engineering and director of UF’s Solar Energy and Energy Conversion Laboratory.
“There are other technologies for air cleaning, but for air disinfection, there is no more effective system,” Goswami said. The photocatalytic air cleaning system relies on the interaction between light and titanium dioxide, a simple and widely available chemical. When light is absorbed into the titanium dioxide, it acts as a catalyst to produce an oxidizing agent. The agent, called a hydroxyl radical, “is like a bullet for the bacteria,” Goswami said, destroying dust mites, mold spores and pathogens by disrupting or disintegrating their DNA.
Goswami came up with the system in the mid 1990s as a cure for so-called “sick building syndrome,” when poor ventilation and a build-up of mold or mildew cause illnesses for people who work inside. Initial research proved that the system kills the mold spore, aspergillus niger, considered to be one of nature’s hardiest spores, he said. More recent research has shown that the system also destroys bacillus subtilis, a spore that causes food spoilage and is a cousin of the anthrax spore, bacillus anthracis.
“In the laboratory, we normally test with nonpathogenic bacteria that are closely related to pathogenic bacteria, so there’s no risk to people,” Goswami said. “As we expected, our tests showed the system was effective against bacillus subtilis.”
The technology is an improvement over traditional filter-based systems in part because there is no opportunity for bacteria to collect and multiply on the filters that clear it from the air, he said. “Filters can actually increase the danger because they concentrate the bacteria,” he said. The system is also an improvement over systems that use ultraviolet light, which do not consistently kill all the bacteria, he said.
Goswami said the technology could be installed in central ventilation systems to decontaminate buildings or homes or used in specific locations where contamination is feared. Given the incidents of anthrax contamination within the U.S. Postal Service, one application would be to install it in mail sorting or collection areas, he said.
“This is affordable for people. A central system for a single-family house would probably be in the range of $1,000 to $1,500,” he said.
As part of UF’s technology transfer mission, the technology was patented and licensed to Universal Air Technologies, which sells a variety of portable and central air purification systems based on the technology.
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Would need to have an FDA test I am sure , that should only take 2 to 5 years!
It looks like standard HEPA filters can catch the spores, but I'm not sure what kills them. Titanium dioxide sounds like the stuff you put on your nose to prevent sunburn.
VOL.: 47 (1989) (p. 307)
CAS Nos.: 13463-67-7 - Titanium dioxide; 1317-70-0 - Anatase titanium dioxide; 1317-80-2 - Rutile titanium dioxide
Chem. Abstr. Name: Titanium dioxide
5. Summary of Data Reported and Evaluation
5.1 Exposures
Titanium dioxide is a white pigment produced mainly from ilmenite (iron titanate) and natural rutile (titanium dioxide). It is widely used in paints, paper, plastics, ceramics, rubber, inks and a variety of other products. Occupational exposure to titanium dioxide during its production, the production of paints, in painting trades and during other industrial use is likely to be extensive, but there is a paucity of data on levels, both occupational and environmental.
5.2 Experimental carcinogenicity data
Titanium dioxide was tested for carcinogenicity by oral administration in one strain of mice and in one strain of rats, by inhalation in two strains of rats, by intratracheal administration in one strain of hamsters, by subcutaneous injection in one strain of rats and by intraperitoneal administration in one strain of male mice and two strains of female rats. Increased incidences of lung adenomas in rats of both sexes and of cystic keratinizing lesions diagnosed as squamous-cell carcinomas in female rats were observed in animals that had inhaled the high but not the low doses of titanium dioxide. Oral, subcutaneous, intratracheal and intraperitoneal administration did not produce a significant increase in the frequency of any type of tumour in any species. Intratracheal administration of titanium dioxide in combination with benzo[a]pyrene to hamsters resulted in an increase in the incidence of benign and malignant tumours of the larynx, trachea andlungs over that in benzo[a]pyrene-treated controls.
5.3 Human carcinogenicity data
The only available epidemiological studyprovided inconclusive results.
5.4 Other relevant data
Titanium dioxide did not induce morphological transformation in mammalian cells or mutation in bacteria.
5.5 Evaluation
There is inadequate evidence for the carcinogenicity of titanium dioxide in humans. There is limited evidence for the carcinogenicity of titanium dioxide in experimental animals. Overall evaluation
Titanium dioxide is not classifiable as to its carcinogenicity to humans (Group 3).
I think that's zinc oxide...:)
Yes, you COULD use ZnO paste on your nose- but what I like to do in Hawaii is to get one of those nifty little umbrellas from my drink ( of course I have to finish the drink first!), then duct-tape it to my nose. Works great, and is a great conversation-starter...
TiO2 is the white hiding pigment of choice in the paint industry. From what I understand, it's also used to color any of a number of consumer products, ranging from paper to food. Any time you see white, guess TiO2, and you're probably right.
??? Hydroxyl radical :OH ???
That would imply that the catalyst acts only on moisture in the air, stripping off one of the hydrogen atoms. I question whether the good doctor's been quoted correctly.
My guess would have been that the system generates oxygen free radicals or ozone, and not the hydroxyl radical. Whether that's the case or not, wouldn't an active ozone generator be better than this passive light-catalyst generator?
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