After sampling, the plates were incubated for 24 hours in a lab and the number of colonies was counted. The plates contained growth media particularly suited for fungi commonly found in indoor environments, including Penicillium and Zygomycetes.
Each treatment was tested separately by collecting multiple samples from each 3-by-3-foot section before and after treatment: vacuuming alone, the application of UV-C light alone, or a combination of UV-C light and vacuuming. In each case, the carpets were vacuumed at a speed of 1.8 feet per second for two minutes.
Overall, vacuuming alone reduced microbes by 78 percent, UV-C light alone produced a 60 percent reduction in microbes, and the combination of beater-bar vacuuming and UV-C light reduced microbes on the carpet surfaces by 87 percent. When looking at the microbe quantities, the researchers found that, on average, vacuuming alone removed 7.3 colony-forming units of microbes per contact plate and the UV-C light removed 6.6 colony-forming units per plate. The combination of UV-C light and vacuuming yielded the largest reduction in colony-forming units: 13 per plate.
"We concluded that the combined UV-C-equipped vacuum produced approximately the sum of the individual effects, and therefore the UV-C was responsible for an approximate doubling of the vacuum cleaner's effectiveness in reducing the surface-bound microbial load," Buckley said.
Surfaces in residential settings, and especially carpets, are seen as potentially posing health risks because they are reservoirs for the accumulation of a variety of contaminants. Those most susceptible to infection, including the elderly, asthmatics, the very young and people with compromise
|Contact: Timothy Buckley|
Ohio State University