Ultraviolet Germicidal Irradiation for Reducing Disease Transmission and Energy Use

1. Ultraviolet Germicidal Irradiation for Reducing Disease Transmission and Energy Use Shelly L . Miller Associate Professor, Mechanical Engineering Environmental Engineering ProgramUniversity of Colorado, Boulder

2. Objectives Since 1997, our research group has studied the efficacy of ultraviolet germicidal irradiation (UVGI) for inactivating airborne bacteria, viruses, and fungal spores Investigated temperature, relative humidity, and photoreactivation affects, as well as UV radiation distribution, air mixing, and lamp type Funded by CDC, NIOSH, Gilbert Foundation, NSF, and Industry partners Experimental paradigms include Multi-pass Intrinsic Upper-room air UV-HEPA air cleaners Single-pass In-duct Small-scale personal devices CFD Modeling

3. UVGI as an Engineering Control The use of ultraviolet germicidal irradiation (UVGI) for the sterilization of microorganisms has been studied since the 1930s, mostly surface and water effects Microbes are uniquely vulnerable to radiation at wavelengths at or near 260 nm due to the resonance of this wavelength with molecular structures This wavelength is not naturally observed at the earth�s surface � it is absorbed in the stratosphere by ozone

4. UVGI Lamps mercury vapor lamps are most commonly used in applications, providing 254 nm radiation Mercury toxicity is a concern in some applications Non-toxic sources are not yet commercially available We are assessing prototype diodes and xenon lamps Xenon produces peak radiation at 242 nm

5. UV Irradiation and DNA

6. Guidelines for Preventing the Transmission of M. tuberculosis in Health-Care Settings Environmental controls are the second line of defense in the TB infection control program, after administrative controls Environmental controls include technologies for the removal or inactivation of airborne M. tuberculosis These technologies include local exhaust ventilation, general ventilation, HEPA filtration, and UVGI (MMWR December 30, 2005 / 54(RR17);1-141)

7. Multi-pass IntrinsicUpper-room air UV-HEPA air cleaners

8. Building applications Crowded environments where unsuspected infectious persons may be present (e.g. jails, homeless shelters, hospital waiting rooms) Rooms in which infectious aerosol may be generated (e.g. hospital treatment and isolation rooms, rooms in a home, indoor pool facilities) and additional control is needed Rooms in which HVAC retrofits are difficult to do but additional air changes are needed to reduce risk of infections (e.g. hospital treatment and isolation rooms)

9. Measles in Schools Wall-mounted UV lamps installed in three NY schools showed no difference in measles incidence, but the UV lamps did modify the spread of the disease: in the school with the most lamps, the outbreak occurred over 4 months, compared to over 1 month in the school with no lamps (Perkins et al., 1947)

11. CU Larson Laboratory T and RH control 87 m3 Full-scale computer controlled HVAC system provides ventilation air, both outdoor and recirc, at 2-8 ACH

12. Z Value First order reaction rate coefficient IRUV (sec-1) normalized by average UV fluence rate (?W cm-2) Z-value is directly proportional to UVGI inactivation rate a higher Z-value indicates a lower resistance of the microorganism to inactivation by UV radiation and vice versa Adopted from medical community (Riley et al. 1976; Riley, 1988, Riley and Nardell 1989)

13. Z value for Aspergillus versicolor is order of magnitude smaller than the Z value for M. parafortuitum (Kujundzic et al., 2005)

15. Photoreactivation may be an important factor95% RH, 25 �C, 0 ACH ventilation Effects observed in intrinsic configuration, but not at full-scale (Peccia and Hernandez 2001) (Xu et al., 2005)

16. Increasing UV fluence rate does not increase inactivation rate linearly (Xu et al., 2005)

17. 90% --> Z=3.9 50% --> Z=7.9 20&% --> Z=9.290% --> Z=3.9 50% --> Z=7.9 20&% --> Z=9.2

18. 90% --> Z=3.9 50% --> Z=7.9 20&% --> Z=9.290% --> Z=3.9 50% --> Z=7.9 20&% --> Z=9.2

19. Effectiveness (E) Quantifies improvement in indoor air quality that is associated with the technology�s use

20. With Impactors, we measured for B. sub at 0 ACT 95 and 91 % effectiveness. For M. para at 6 ACH we measured 99 % effectivenessWith Impactors, we measured for B. sub at 0 ACT 95 and 91 % effectiveness. For M. para at 6 ACH we measured 99 % effectiveness

22. HEPA-UV Air Cleaners In an Indoor Therapy Pool Building

23. Culturable Bacteria

24. Single-pass In-ductSmall-scale personal devices

25. Building applications Irradiation of cooling coils an drip pans Limited scientific studies to assess impact of this application Anecdotally it seems to work well Two scientific studies recently completed showed no effect Irradiation of recirculation air within HVAC system

26. HVAC Guinea Pig Study Guinea pigs exposed simultaneously in 2 separate chambers, one receiving unchanged air from a TB ward, and the other, ward air that was irradiated with UV-C. A total of 63 guinea pigs contracted TB over a 2-year period, and all were breathing unirradiated air from ward (Riley et al. 1962)

27. Residential Asthma Study of 19 asthmatic children in homes with central AC systems in which UV lamps were installed showed a statistical improvement in PEFR variability in subjects with UV lamps compared to no UV lamps (Bernstein et al. 2006)

28. Impact of in-duct UV on office workers Double-blind cross over study of 771 participants 3 office sealed air-conditioned buildings UV was alternately off for 12 weeks, on for 4 weeks, and repeated 3 times Operation of UVGI reduced surface microbial contamination by 99% Use of UVGI was associated with significantly fewer work-related symptoms overall, as well as respiratory and mucosal symptoms than was non-use (Menzies et al. 2003)

29. Impact of in-duct UV on office workers

30. In-Duct UVGI Bacteria continuously aerosolized outside near HVAC supply intake High wattage UVGI in recirculation duct Sample upstream, downstream

31. In-Duct UVGI Single Pass Efficiency

32. Small-Scale Personal Device Requirements High flow rate Non-toxic UVGI source Coated to enhance reflectance

33. Apr 30, 2008 33 UV Source LEDs solid state, expensive, low UV efficiency (~0.3%), 45-65 mW UV array Mercury Cheap, efficient (~10%), toxic, peak at 254 nm, 1 W bulb Xenon Not commercially avail, efficient (~10%), nontoxic, peak at 270 nm, prototype built for project

34. Apr 30, 2008 34 CU Experimental Test Facility

35. B. Subtilis Hg uncoated tube

36. Energy Implications Mostly anecdotal evidence One MS thesis presents economic analysis More research needed

37. Anecdotal Evidence Tacoma Jail Installed UV lights in HVAC VAV box/cooling coils, went from 100% outside air to 70% OA and 30% recirc Saved 34,100 therms of natural gas/yr Review of utility bill confirms they saved > $70,000/yr in natural gas, overall saved $55,000 after accounting for parts/labor

38. Anecdotal Evidence Florida Hospital Installed UV lights in one 6000 cfm unit, near cooling coils where visible mold and clogging of coil apparent Within weeks of installation, static pressure over coil decreased from 1.8 in wg to 0.7 in wg Air velocity doubled from 230 fpm to 520 pfm $4900 in savings - $2000 installation cost = $2900 Also observed less mold build up in duct work, reducing maintenance costs

39. Anecdotal Evidence Boston Museum of Fine Arts Noticed a mold problem in humidifiers Had to drain and clean humidifiered almost daily Installed UVGI devices above humidifier sump and downstream of chilled water coils Standing water much clearer, huge reduction in maintenance and cleaning procedures American Electric Power, Dallas Installed UVGI in air handlers Eliminated cleaning programs Saw significant drop in pressure across coil, translating into energy savings of $139,000 over two-yr period

40. Dreiling 2008, An Evaluation of UVGI Technology in Health Care Facilities Compared three systems to a baseline 3900 cfm HVAC system: Upper-room UVGI system HVAC system with increased ACH UVGI system in an AHU

41. Dreiling 2008, Economic Evaluation Summary Upper-room UVGI increased predicted time for 99% disinfection from 46 minutes to 18 minutes Increased ACH to 15.2 from 6 ACH 62% increase in total cost HVAC system with increased ACH Similar to upper room UVGI, in both cost and increased ACH UVGI in AHU Room still at 6 ACH Cooling coils cleaned More focused on the fan energy consumption

42. Acknowledgements CDC, NIOSH, NSF, Gilbert Foundation, Industry Sponsors Students at CU: Elmira Kujundzic ,Fatimah Matalkah, Cody Howard, Jordan Peccia, Peng Xu Colleagues: Mark Hernandez, Millie Shafer, Kevin Fennelly, Byron Jones, DTU faculty, Joint Center for Energy Management

43. References Dreiling J. (2008). An Evaluation Of Ultraviolet Germicidal Irradiation (UVGI) Technology In Health Care Facilities, MS Thesis, Kansas State University. Bernstein JA. (2006). Health effects of ultraviolet irradiation in asthmatic children�s homes, J Asthma 43:255-262. Jamriska M et al. (2000). Effect of ventilation and Filtration on Submicrometer Particles in an Indoor Environment Indoor Air 10(1):19-26 Kujundzic E et al. (2007). Ultraviolet germicidal irradiation inactivation of airborne fungal spores and bacteria in upper-room air and in-duct configurations, JEES 6:1-9. Kujundzic E et al. (2006). Air cleaners and upper-room air UV germicidal irradiation for controlling airborne bacteria and fungal spores, JOEH 3:536-546. Kujundzic E et al. (2005). Effects of ceiling-mounted HEPA-UV air filters on airborne bacteria concentrations in an indoor therapy pool building, JAWM 55:210-218. Mendell MJ et al. (2002). Indoor particles and symptoms among office workers: results from a double-blind cross-over study, Epidemiology 13:296-304. Menzies D et al. (2003). Effect of ultraviolet germicidal lights installed in office ventilation systems on workers� health and wellbeing: double-blind multiple cross-over trial, The Lancet 362:1785-1791. Perkins et al. (1947). Effect of ultra-violet irradiation of classrooms on spread of measles in large rural central schools, Amer J Public Health 73:529-537. Riley et al. (1962). Infectiousness of air from a tuberculosis ward, Amer Rev Respir Disease 85:511-525. Xu P et al. (2005). Impact of environmental factors on efficacy of upper-room air ultraviolet germicidal irradiation for inactivating airborne Mycobacteria, ES &T, 39:9656-9664. Xu P et al. (2003). Efficacy of ultraviolet germicidal irradiation of upper-room air in inactivating bacterial spores and Mycobacteria in full-scale studies, Atmos Environ 37:405-419. Peccia, J. and Hernandez, M. (2001). Photoreactivation in Airborne Mycobacterium parafortuitum. Appl. Environ. Microbiol. 67:4225-4232.