Characterization of Ultraviolet Upper Room Air Disinfection Devices

Dumyahn, Thomas; First, M.W.

doi:10.1080/00028899908984439

Cited by 36 publications

(28 citation statements)

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“…Up until now, a signi cant increase in the incidence of certain airborne diseases, most notably the one caused by Mycobacterium tuberculosis (TB), was observed in different areas. To protect patients and health care workers who often interact with individuals in high-risk groups, UVGI xtures are currently widely installed in hospitals (Dumyahn and First 1999).…”

Section: Introductionmentioning

confidence: 99%

Control Effectiveness of Ultraviolet Germicidal Irradiation on Bioaerosols

Lin

2002

Aerosol Science and Technology

102

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Because of increasing incidence of microorganism infections, there are concerns in engineering control of indoor microorganism for reducing airborne infectious diseases. Ultraviolet germicidal irradiation (UVGI) was considered to be promising to inactivate microorganisms. In this investigation, the in uences of UV dosage, microorganism species, and relative humidity on UVGI effectiveness were evaluated in a laboratory test chamber. A Collison nebulizer generated aerosols containing Escherichia coli, Bacillus subtilis spores, cells of Candida famata var. areri, and spores of Penicillium citrinum. The UVGI control effectiveness was determined as the ratio, NS=N 0 , where NS and N 0 were the colony concentrations collected by Andersen one-stage samplers at UVGI dosages of D and zero, respectively. In regard to 99% microorganism inactivation, the UVGI dosage ranges were 1017 to 2356 ¹W s/cm 2 , 15949 to 19345 ¹W s/cm 2 , 12917 to 17497 ¹W s/cm 2 , and 47984 to 89419 ¹W s/cm 2 for E. coli, B. subtilis, yeast, and P. citrinum, respectively. Signi cantly, the microorganism susceptibilities of E. coli were the highest and P. citrinum were the lowest. In regard to relative humidity effects, it was observed that the microorganism susceptibilities at 80% relative humidity were lower than those found at 50% relative humidity for all 4 types of the evaluated microorganisms.

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Section: Introductionmentioning

confidence: 99%

Control Effectiveness of Ultraviolet Germicidal Irradiation on Bioaerosols

Lin

2002

Aerosol Science and Technology

102

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“…These levels suggest that time spent looking directly at a lamp should not exceed 5 min day ¡ 1 . Newer designs of louvers avoid these problems (Dumyahn and First 1999).…”

Section: Discussionmentioning

confidence: 99%

Evaluation of a Methodology for Quantifying the Effect of Room Air Ultraviolet Germicidal Irradiation on Airborne Bacteria

Miller¹,

Macher²

2000

Aerosol Science and Technology

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ABSTRACT. As a result of the recent resurgence in tuberculosis (TB) and the increasing incidence of multidrug-resistant TB, there has been renewed interest in engineering controls to reduce the spread of TB and other airborne infectious diseases in high-risk settings. Techniques such as the use of lamps that produce ultraviolet germicidal radiation may reduce exposure to infectious agents by inactivating or killing microorganisms while they are airborne. We designed and evaluated a test method to quantitatively estimate the ef cacy of germicidal lamps, in conjunction with dilution ventilation, for reducing the concentration of viable airborne bacteria. Bacterial particles were generated in a 36 m 3 room and collected with midget impingers at 5 -7 locations. The effectiveness of the control technique was determined by comparing concentrations of culturable airborne bacteria with and without the control in operation. Results for a single, 15 W germicidal lamp showed reductions of 50% for Bacillus subtilis (B. subtilis) and Micrococcus luteus (M. luteus); tests with Escherichia coli (E. coli) showed nearly 100% reduction (E. coli were isolated only from the sampler nearest the aerosol source when the lamp was operating). The addition of louvers to a lamp greatly reduced its ef cacy. Decay experiments showed that roughly 4 -6 equivalent air changes per hour were achieved for B. subtilis with one or two lamps operating. These preliminary experiments demonstrated that this methodology was well suited for these evaluations and identi ed factors that could be modi ed to re ne the study design for future work.

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“…The values are from a previous study described elsewhere (13) and from Appendix A. For the corner fixtures listed in Table I, electrical input was 36 W, whereas the corner fixtures for which the UV power output was measured, (13) electrical input was 18 W, although the fixtures themselves were essentially the same. For these fixtures, UV power output should be directly proportional to the electrical power input.…”

Section: Upper-room Uv Fixturementioning

confidence: 99%

Fundamental Factors Affecting Upper-Room Ultraviolet Germicidal Irradiation—Part II. Predicting Effectiveness

Rudnick

First

2007

Journal of Occupational and Environmental Hygiene

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Compared with increasing outdoor air ventilation rate, upper-room ultraviolet germicidal irradiation (UVGI) is an attractive technology for lowering the indoor concentration of airborne microorganisms and thereby reducing the risk of airborne transmission of disease. With relatively modest vertical air circulation, most of the air in a room can be irradiated in a relatively brief time period without noise or significant power consumption. The hypothesis tested in this study is that the efficacy of upper-room UVGI to inactivate or kill airborne infectious microorganisms can be determined from an index of UVGI effectiveness, a dimensionless parameter designed to characterize adequacy of vertical air circulation, amount of UVGI provided, and their interaction. This index of effectiveness, which is determined independently of microbiological testing, was found to correlate well with experimental measurements made in a room-size chamber. A comparison of two other dimensionless parameters - the irradiation number and mixing number, from which effectiveness index is calculated - provides insight into whether the quantity of UV provided to the upper room or the intensity of the vertical air circulation is the controlling factor for effective application of upper-room UVGI. The irradiation number is calculated from the UV power output of the fixture(s), a parameter that is fixture specific and much easier to measure than mean fluence rate. An equation was also developed that relates UV fixture power output to mean fluence rate in either the irradiated zone or the entire room. In addition, reductions in viable microorganism concentration due to UVGI predicted from a two-box model are compared with experimental measurements.

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Characterization of Ultraviolet Upper Room Air Disinfection Devices

Cited by 36 publications

References 0 publications

Control Effectiveness of Ultraviolet Germicidal Irradiation on Bioaerosols

Control Effectiveness of Ultraviolet Germicidal Irradiation on Bioaerosols

Evaluation of a Methodology for Quantifying the Effect of Room Air Ultraviolet Germicidal Irradiation on Airborne Bacteria

Fundamental Factors Affecting Upper-Room Ultraviolet Germicidal Irradiation—Part II. Predicting Effectiveness

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