UV-C Light Application in HVAC Systems by rtu18834

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									         UV-C Light
        Application in
        HVAC Systems
               IAQA Annual Conference
                     June 12, 2008




Richard J Shaughnessy, PhD
Program Director IAQ Research
University of Tulsa
     918-230-
Ph: 918-230-3908
Email: rjstulsau@aol.com
        National Expenditures for IAQ
       Problem Prevention or Mitigation
                          (LBNL – 58694, June 2005)

• $15.9 billion annual business (range $12-20 billion)
   –   Air clng and improved filtration………$1.5 billion
   –   IAQ Consultant services……………….$2.1 billion
   –   Building Remediation………………….$3.4 billion
   –   Duct Cleaning…………………………..$ 4 billion
   –   Asbestos/lead abatement……………….$ 4 billion
   –   IAQ litigation/insurance………………..$500 million
   –   Radon Mitigation……………………….$200 million
   –   Certification/labeling……………………$100 million
   –   Laboratory Services…………………….$100 million
          Truth or fiction on
             air cleaning
         “Removes virtually any contaminant
         including gases and VOCs”
         “Relieves asthma and allergies”
         “Eliminates allergies and other
              maladies caused by molds”
         Eliminates almost 100% of such harmful
         airborne particulates as dust, bacteria,
         viruses, pollen, mold, spores, tobacco,
         and general room odors”

Can Claims be made that are questionable w/o consequences?
                       Better Airplane Ventilation
                         Cuts Spread of Disease,
                              Report Says


                         -- Increasing ventilation in airliners can
March 11, 2006 (Bloomberg)
reduce the spread of infectious diseases such as influenza,
tuberculosis and severe acute respiratory syndrome, a report in the
Lancet medical journal said.

                               three-
During the SARS outbreak, a three-hour Air China flight from
Hong Kong to Beijing accounted for 22 of 37 people who
contracted the illness after their journey, the report said. ``That Air
                       super-                        Gendreau,
China flight 112 was a super-spreading event,'' said Gendreau, who has conducted four
studies on airplane medical issues.

Without ventilation on a plane grounded for three hours in Texas
                                                               flu
in 1979, 72 percent of all passengers on the flight caught the flu
within 72 hours.
     HVAC SYSTEMS
The IAQ Equipment Basics




Drainability                  Accessibility
               Cleanability
     Emerging Technologies


•   P.C.O.
•   Sorbent
•   Ionization/electrostatic devices
•   Media filtration
•    UV-
     UV-C
Photocatalytic Oxidation
        (PCO)
• Titanium dioxide (TiO2) is a
  semiconductor photocatalyst
• UV light-driven catalytic oxidation of
  gas phase contaminants
• Resultant oxidation of VOCs
  and degradation of
  bioaerosols
     PCO Challenges
• formation of products of incomplete
  oxidation (primarily aldehydes)
• reaction rate inhibition due to
  humidity
• mass transport issues associated
  with
  high-flow rate systems
• catalyst deactivation and
  inorganic contamination
  (dust and soil)
      Application of UV-C
• Historically used on bacteria in tuberculosis
  isolation rooms, hospitals for >100 yrs

          upper-
• Duct or upper-room irradiation mounts

• CDC recommends use as an engineering
  control (i.e. ventilation, HEPA)

• Not as effective on fungal
  spores compared to
  bacteria> 100 y
Lamp Output Factors
• Air velocity (cooling effect reduces
  intensity)
• Temperature of ambient air
• Age of lamp (intensity depreciates
  quickly in first 100 hours)
• Cleanliness (dust buildup)
• Wattage
• Reflectance
• Inverse square law (intensity ↓ in
  proportion to square of distance from
  lamp)
  UV Microbial Factors
• Dose = (intensity) x (time)
                      on…
  lethal dose depends on…
     • size of radiation field
     • residence time in field
     • specific microorganism
     • Humidity (R.H. > 50%, germicidal effect ↓)
       Peccia,
      (Peccia, et al. 2001 Aerosol Sci & Tech)

• Spores may be damaged, but not rendered
  inviable
Effectiveness UVC Inactivation at Varied RH (max’m at 50%)




                                                    Xu,
                                                   (Xu, Miller, et al., 2005)
Upper-Room UV-C
                                          Experiment 2



                       100                                                Wintertime ventilation
                        90   0 ACH                                         conditions decreased
                        80                                              effectiveness from 89% to
UVGI Effectiveness %




                        70                                                 12% when the mixing
                        60                                                     fans were off
                        50                                              (supply air T > room air T
                                                       6 ACH
                        40                                               result in short circuiting)
                        30
                                           Winter conditions
                        20
                                                                         M. parafortuitum
                        10
                         0
                                 mixing       no mixing
                                                               mixing   (Xu, Miller, et al., 2005)
                     Upper-
   UV Air Cleaners & Upper-Room
           UV Irradiation
               Kujundzic,
         JOEH, Kujundzic, Miller et al, 2006



• Lamps in portable air cleaners (PACs)
  inactivated bacterial cells & fungal spores
  captured on filter media
• UV-C lamps did not provide added benefit
  to air cleaning inactivation in PACs
• Air cleaning via combined PACs & upper
  room UVGI indicated significant
  removal/inactivation
UVC in Air Handling
       Units




 active
          inactive
                                   Mean Concentrations of Fungi Occurring on Insulation
                                   Samples from Air Handling Units Before and After UV
                                                       Installation
                              100,000,000
   Colony forming units/cm2




                                                                            2,236,687
                               10,000,000   212,622   211,885

                                1,000,000                          30,507

                                 100,000

                                  10,000
                                                                                        Study Floor
                                                                                        Control Floor
                                   1,000

                                     100

                                      10

                                       1

                                                 Before                After
Levetin, E.,                                Applied and Environmental Microbiology,
Shaughnessy, R.J.,                          Vol 67 #8, 3712-3715, August, 2001.
Rogers,C.
             Mean Concentrations of Viable Airborne Fungi within
             the Air Handling Units Before and After UV Installation

          1000000

          100000                                                         23,232

           10000       2,165      2,255
C FU/m3




                                                              298.25                                Study
            1000
                                                                                                    Floor
             100                                                                                    Control
                                                                                                    Floor
              10

               1

                          Before                                   After

                                   Note: samples taken w/in AHU immediately after units shut off;
                           Effect may be attributed to lower airborne counts emitted from vibration of lining.
              Summary
• Positive correlation between operation of
  UV-
  UV-C lamps and reduction of microbial
  growth in duct lining and drain pan
  samples from AHUs
• Effect on bacteria in water more
  pronounced than on fungi
• No ozone buildup noted


                          Levetin, Shaughnessy, Rogers, 2001
             (cont’
     Summary (cont’d)
  UV-            line-of-
• UV-C is direct line-of-sight
  mechanism; areas not irradiated
  showed no visible improvement
• Further studies needed as to overall
                    UV-      AHUs,
  effectiveness of UV-C in AHUs, and
  the effect on the passing air stream


                          Levetin, et al., 2001
  Effectiveness of UV in
       Ductwork
• Vegetative bacteria more susceptible
  while spore-forming bacteria and
  fungi more resistant
• Reliance on design eqns to predict
  kill may be prone to error; actual
  testing under environmental
  conditions recommended
             Foarde et al., A.R.T.I., Nov 2002
               http://www.arti-21cr.org/research/completed/finalreports/40030-final.pdf
In-                UV-
In-duct studies of UV-C
    installed systems
 100%
  90%
  80%
  70%                                         91%
  60%
  50%                                                                test 1
                                     80%                             test 2
  40%     75%
  30%
  20%
  10%
   0%
           Aspergillus              Mycobacteria

         Duct velocity = 2.2 m/s (7.2 ft/s)
   No inactivation at velocity of 5.1 m/s (16 ft/s)
                     Jour Env. Eng. Sci.,, Kujundzic, Miller et al, 2007
      Biological Inactivation
     Efficiency of HVAC In-Duct
     Ultraviolet Light Devices
    http://www.epa.gov/nhsrc/news/news062606.html

• U.S. EPA funded studies examining
  effect of in-duct devices on bacterial
  spores, vegetative bacteria, MS2
  virus
• Homeland Security interests
• Vegetative bacteria more susceptible
  while spore forming bacteria and
  fungi more resistant
• Inactivation related to dose
                EPA funded studies on UVC in Ductwork
                                                                              Airborne Inactivation Efficiencies(%)
                                                    Measured                 Spore form of    Vegetative form        Virus
UVC Device                              Lamps        Dosage         Power       bacteria         of bacteria         (MS2
                                                                     (w)    (B. atrophaeus)   (S. marcescens)   bacteriophage)
                                                   (µW-s/cm2)

Abracair, LLC                             12      447 (376 - 550)   6480-        6.9               99.8              59
                                                                    6720

American Ultraviolet Corp.                 4      582 (490 – 716)    169          9              ≥99.96b             75
ACP-24/HO-4

American Ultraviolet Corp.                 4      295 (249 – 363)    94           0              ≥99.8b              46
AeroLogic Model AD24-4

Dust Free                                  1      247 (208 – 304)    53           4                 99               39
Bio-Fighter 4Xtreme Model 21

Lumalier                                   8          3180           568          40             ≥99.98b             82
ADPL-60-8                                         (2678 – 3914)

Novatron, Inc.                             6         >42,342         748       ≥99.9b            ≥99.94b           ≥99.9b
BioProtector BP114i                              (35,656-52,113)

Sanuvox Technologies, Inc.                 5          16,439         944          93             ≥99.97b             99
UV Bio-Wall 50                                   (13,843-20,223)

Steril-Aire, Inc.                          6          19,826         421          96             ≥99.96b             99
Model SE1 VO w/GTS 24 Emitter                    (16,696-24,401)

Ultra Violet Devices, Inc.                12           7651          755          71             ≥99.98b             98
Altru-V V-Flex                                    (6,443 – 9,416)
a: The systems were run at 0.93 m3/sec (1970 CFM; 500 fpm), except the Novatron device was run at 0.14 m3/sec (300 CFM;
300 fpm).
            ANTIMICROBIAL
            STUDY RESULTS
• Inhibits growth on clean filters; growth still
  occurs on dust-loaded media
• Under normal use, filters (treated or not) are
  not expected to become microbial source
                                ASHRAE Journal, Dec, 2000
                               Foarde,K., Hanley,J., Veeck,A.
          UV-
Effect of UV-C in HVAC on
    Workers’
    Workers’ Health
• Cooling coil irradiated by UV-C lights
  Microbial/endotoxins were reduced on irradiated
    surfaces
  Some worker-related symptoms also reduced
• Limitations:
  –   Only 3 bldgs; nonrandomized intervention
  –   Very low initial microbial concentrations
  –   No effect on thermal/chemical indices
  –   Only slight effect on worksite air microbes
  –   No explanation for apparent health effects
        Menzies,
        Menzies, et al, Lancet, Nov, 2003
                    In-     UV-
Clinical Effects of In-duct UV-C
       installed systems
Guinea pigs exposed simultaneously in 2 separate
chambers, one receiving unchanged air from a TB ward ward,
                                                 UV-
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)
Study of 19 asthmatic
children in homes with          0.12

central AC systems in            0.1


                              Median PEFR var
which UV lamps were             0.08


installed showed a              0.06

                                0.04
statistical improvement in      0.02
PEFR variability in subjects       0

with UV lamps compared                  UV        no UV


to no UV lamps (Bernstein
et al. 2006)
      FOR IMMEDIATE RELEASE
      Tuesday, April 18, 2006


           Early life exposure to dust may protect against asthma, from the
                       Journal of Allergy and Clinical Immunology
Exposing children early in life to dust and other microbial agents could protect
them from developing asthma, according to new research in the May issue of the Journal of Allergy and
Clinical Immunology.

“Does early indoor microbial exposure reduce the risk of asthma? The Prevention and Incidence of Asthma and
Mite Allergy birth cohort study” can be found online at www.jacionline.org.
The study showed levels of dust and other microbials on the floor correlated to a lower level of asthma
development by age four. The highest exposure group had a lower level of asthma and wheeze, even
when researchers made adjustments for the presence of animals in the home, antibiotic use, dampness, etc.
The study lends support to the "hygiene hypothesis" that an excessively
clean environment in early childhood may predispose some people to
develop asthma.
                       For a copy of the study, contact Karen
                       Janka (kjanka@aaaai.org) at (414) 272-6071.
          Bottom Line!
1. Moisture control
2. Properly designed dehumidifying/cooling
   HVAC processes
3. Drain pans designed to drain
4. Nonporous surfaces installed
   downstream of coils
…should collectively continue to be
  primary approaches to
  controlling microbial growth in
  AHUs

								
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