Effectiveness of UV-C Equipped Vacuum at Reducing Culturable Surface-bound Microorganisms on Carpets.

Eric A. Lutz, Smita Sharma, Bruce Casto, Glen Needham, Timothy J. Buckley

Abstract

Carpets are both sinks and sources for exposure to chemicals, allergens, and microbes and consequently influence health, including asthma, allergies, and infectious diseases. Asthmatics, children, and the immune-compromised are particularly vulnerable to health risks resulting from exposure to carpet contaminants. To address this risk, a commercial upright vacuum cleaner with an ultraviolet germicidal lamp (λ=253.7 nm, UVC) has been developed for residential and commercial uses. However, its effectiveness in reducing microbial load on real-world carpets has not been previously demonstrated. Accordingly, the purpose of the current study was to evaluate the effectiveness of a UVC-equipped vacuum in reducing the carpet surface-bound microbial load. This was accomplished by comparing the carpet microbial surface load from pre- to post-treatment of 9 ft2 in-use carpet sections under three treatment scenarios: 1) UVC alone (UV), 2) the beater-bar plus vacuum (BB+Vac), or 3) a combination of all three (COMB). Each treatment was two minutes in duration. Microbial surface loads were measured by pressing contact plates containing Sabourauds Dextrose agar onto the carpet surface. In-use carpets from three locations were tested in place. The treatment effect was evaluated at two levels. First, we considered the mean reduction in CFU from pre- to post-treatment for each 9 ft2 carpet grid (n = 4 for each treatment). The second level considered each 1 ft2 section using a paired analysis (n = 40 to 49 for each treatment). A total of 125 pre/post-sample pairs were collected across the three treatments. Results showed that all three treatments were associated with a reduction in carpet microbial load (p < 0.0001). The COMB yielded the largest reduction of 13 CFU/plate (87% reduction) and was approximately the sum of the individual effects of either UVC (6.6 CFU/plate, 60% reduction, p = 0.009) or BB+Vac (7.3 CFU/plate, 78% reduction, p < 0.0001). We therefore conclude that a UVC-equipped vacuum approximately doubles the unit's effectiveness in reducing surface-bound microbial load, thereby holding promise as a means for decreasing indoor infectious disease risk.

 

Environ. Sci. Technol. 2010 vol. 44 (24) pp. 9451-5 

doi:10.1021/es1015982

Publication Date (Web): October 29, 2010
Copyright © 2010 American Chemical Society

 

ORIGINAL ARTICLE

 

Effectiveness of UV-C Equipped Vacuum at Reducing Culturable Surface-bound Microorganisms on Carpets.:  Created on March 8th, 2012.  Last Modified on March 8th, 2012

2 Comments

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· 9 years ago

CIRI Comment: We asked Dr. Charles Gerba to comment. His comment follows in quotes.

"Actually this [study] makes sense to me. We did studies in homes over time and found that coliform bacteria were eliminated and bacterial numbers were reduced in carpeting. The media used in the referenced study largely detects fungi, which are certainly abundant in carpets. The effectiveness of UV light is mostly at the surface of the carpeting where the greatest exposure to bacteria and viruses occur. I believe children in homes, who are the closest to carpeting could benefit from such a device. Small children crawl on the floor and put their hands in the face up to 81 times per hour. Thus, almost anything they get on their hands goes right in their mouth. Also, there have been at least two outbreaks of norovirus in hotels where vacuum cleaners were believed to cause the spread of the virus. We have found that Salmonella and E. coli will grow in vacuum cleaner dust. This area needs more study to clarify the benefits of UV light in vacuum cleaners.

Chuck Gerba"

[CIRI NOTE: Dr. Chuck Gerba Bio

Charles P. Gerba, Ph.D. is an internationally recognized environmental microbiologist and Professor of Environmental Microbiology in the Departments of Microbiology and Immunology, and Soil, Water and Environmental Science, at the University of Arizona. His credentials include a B.A. in Microbiology, Arizona State University, 1969, and a Ph.D. in Microbiology, University of Miami, Florida, 1973. He is also a member of the American Academy of Microbiology.

Dr. Gerba has authored more than 400 articles including several text books in environmental microbiology and pollution science. He actively conducts research on the development of new disinfectants and drinking water treatment processes, new methods for the detection of pathogens, and microbial risk assessment. He was a member of the U.S. Environmental Protection Agency (EPA) Committee on the development of the "Guide Standard and Protocol for Testing Microbiological Water Purifiers," which forms the basis for testing the performance of water treatment devices used for outdoor recreation. He is a member of the U.S. EPA's Science Advisory Board Committees on Drinking Water and Research Strategies.

The public knows Dr. Gerba best for his crusading on behalf of household hygiene. He has made frequent media appearances, including Good Morning America, Today, and Dateline, and has been quoted numerous times in international and national reports, magazines and newspapers.]

March 10th, 2012 | 2:57pm Reply
· 9 years ago

First of all, carpets should not be installed in healthcare environments or areas where "high risk of infection individuals" are housed. Beyond this obvious fact is this....UV-C will fade the color in most carpets when used repeatedly, especially in high traffic areas and lanes which are typically vacuumed most often. UV-C on a vacuum is an overreach by ambitious marketing people and just a bad idea. The fact that David Oreck bought out that ill-conceived Halo company adds no credence to the argument for using UV-C on the bottom of a vacuum. Next we will see a UV-C hairbrush to kill lice eggs and a UV-C eggbeater to "prevent salmonella"....
Joseph K. Schulman

March 10th, 2012 | 9:37am Reply

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