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Applying Upper Room UVGITheory, Lamps, Fixtures,
Emission Characteristics and Applications
Building Design and Engineering Approaches to Airborne Infection Control
Harvard School of Public HealthBoston MA
August 3, 2010
Richard L. Vincent, FIES, LEED® APMount Sinai Hospital
Mt. Sinai School of Medicine
Session Objectives• Introduce basic principles for applying
upper room UVGI Equipment• Learn features of upper-room UVGI
fixtures• Types of fixtures available
– Fixture components (lamps, ballasts, optics)– Characteristic emission patterns, – Where and how to place in large and small rooms.
• Learn from Case Studies
Factors Influencing Effectiveness• UV Irradiance and Dose
– UV Dose (irradiance x time) based on microorganism susceptibility expressed in µW•s/cm2
– Ave fluence for mycobacterium 30 to 50 µW•s/cm2
– Provide uniform UVGI distribution • Upper-Room UVGI Systems and Ventilation
– Experimental studies show UV + ventilation (up to 6 ACH) are additive in microorganism inactivation in well-mixed rooms
– Ventilation over 6 ACH reduces effectiveness due to less resident time of microorganisms in the UV zone.
• Air Mixing– Upper-room UVGI depends on air mixing to lift organisms into the UV field– General ventilation (supply diffusers and return grilles) should be designed to promote
optimal airflow patterns in the room or if air is stagnate a fan provided to enhance mixing with a mixing factor of K=1 being ideal. Usual range in offices is K between 1 to 3.
• Humidity– Relative humidity (RH) should be controlled to be less than 60% for optimal upper-room
applications and comfort; yet it is applied in higher humidity settings with success• Temperature
– UVC lamps operate optimally at 70° F (21 °C) colder temperatures can reduce lamp output
Source: DHHS (NIOSH) Publication 2009-105
Guidelines for Design and Installation of Upper-Room UVGI System
• Determine target microorganism(s) and average UV dose to be delivered by UVGI system– Ave fluence (dose) 30 to 50 µW•s/cm2 for mycobacterium and most viruses.– Higher dose of UV required for spore and fungal organisms consult handbooks for specific doses
• UVC Lamps– Select low or no ozone generating UVC, 254 nm low pressure mercury germicidal lamps which use 5 mg or
less of Hg. • UVGI Fixtures
– Select fixed louvered units when installing in rooms with a minimum of 8 ft (2.7m) of floor to ceiling height– Select open units with a cut-off to minimize UV in lower room for ceilings over 10 ft. (greater than 3m)– Require safety switch to deactivate units when servicing to prevent exposure– Require electronic ballasts with capability to adjust output by dimming.– Test fixtures for performance (output and distribution) using a UVC radiometer
• UVGI System architectural placement for uniformity– Use CAD UVGI program
• UVGI System Installation– Commissioning– Safety– Maintenance
Upper-room UVGI• Fixtures emit germicidal UVC into upper-room
• Microorganisms are deactivated through DNA damage as room air circulates vertically
• Louvered fixtures limit exposures in the lower room to safe levels
Source: K. Banahan
UVC LAMPSTypical Germicidal Lamps
Linear, Folded, Low Hg• Upper air UVGI is
generated by a low pressure mercury vapor discharge lamp– 35% electrical input
wattage is converted to UVC energy for which 253.7 nm is the strongest wavelength
• UVC irradiance is measured in µW/cm2
• Electrical input to the UVC lamp is regulated by a ballast (magnetic and electronic)
1st Low Hg Germicidal Lamps
UV Lamp Spectra Vary• Varies with emission source and
with the lamp envelope– Specialized glass envelope
allows ultraviolet to escape.– Two lamps emitting the same
visible blue light tag can emit much different UV wavelengths
– 185 nm (ozone) wavelength suppressed in upper room and induct applications
– The spectral power distribution (SPD) is critical in photobiological research
– Need standardized test to report SPD
Spectral power distribution of UV-C lamp at 1 nm resolution. Source: R. Levin
Upper-Room UVGI Fixtures Research to provide safer products
(Riley and Nardell)
Louvered fixture designs a response to low ceilings in modern buildings– To reduce direct downward UV
exposure of room occupants– To reduce reflectance from
ceilings to room occupants– Design shared with a number
of manufacturers who have innovated on their approaches
• Open UVGI for High (>9 ft) Ceilings (>2.7 m)
• Louvered UVGI for Low (8-9 ft) Ceilings (2.4-2.7 m)
Source: Martin S et al. ASHRAE Journal Aug 2008 p 34
UVGI Fixture Configurations
Cross Sectional and Open UVGI Wall Mount Unit
Adjustable Output
Dimmable
Electronic ballast
Safety Switch
Single pin
Linear UVC lamp
Parabolic UV reflective
element
Louvers
Upper Room UV-C
2.1 m
Floor Area Coverage
24.2 m2 (not less than 10µw/cm2)
What are the basics of an Upper room UVGI System?
Summary requirements driving Designs for TB irradiation.
• UVC source primarily at 254 nm• UV level measured 1.8 m (6 ft) from floor not to exceed 6000 μJ/cm2 over
8 hours*.• UV Dose = UV irradiance (μW/cm2) * exposure time (seconds)
– For TB, 10 μW/cm2 for 120 seconds = 99% kill (ASHRAE CH-99-12-1)– Customary installation: 30 W UV lamp input power per 18. 6 m2 (200ft2)
• Model Room Studies are suggesting an average UV fluence be used• Key question is how to measure in the field
– Lamp output power ≅ 25% to 33% input power– Lamp efficiency versus lamp temperature and age
• Room vertical airflow rate - TBD (well mixed air is most effective with UVGI)
• Environment temperature (expected system performance in nominal) –21°C (70° F)
• Environment humidity (expected system performance in nominal) – not greater than 75%
• Lamp life/hours of use ≅ 8,736+ hours (1 year = 24x7x52, + safety factor)• 100 hours lamp burn-in∗Application of this value should be based on room occupancy usage.
Plan to Disrupt TB Transmission• Most upper room
installations are designed to interrupt TB transmission From--Most Important to Least Important– Convection--sharing a
room or adjacent space– Recirculation--anywhere in
ventilation circuit– Close Proximity--being
“coughed on”• Consider a whole building
approach where appropriate
Source: South Africa Medical Research Council
Upper-air Irradiation With UV-C(Section View in Hospital Room)
Air-Mixing Critical to Effective UVGI SystemsMeasurement of Mechanical Ventilation
Congregate Waiting Area with Operable Windows and UVGI
Note: UVGI off when working the upper-room
UVGI Ceiling Mount FixturesAir-Mixing with Paddle Fans
Open UVGI Fixtures in High Bay Covering Possible Transmission into Patient Rooms from Corridor or from Patient Rooms into Corridor
Hospital Room - UV Lamp
Old style fixtures- intensity 10 x 0.2 µW/cm2
Unventilated bldg.
MDR TB patients
No TST conversions
Senior Drop-in CenterBefore 360° Closely Space Louvered Pendant
After more efficient pendant wider spaced louvers.
Placement of UVGI FixturesTUSS Case Study
Grand Central Drop-In CenterSt. Agnes Church Basement
143 E 43rd Street NYC
Applying Upper Air UVGIin Congregate Settings—New York City
• TUSS (1997-2004) was a double-blind, placebo controlled field trial in 6 USA cities, with 14 shelters
• Nearly 1200 UVGI fixtures were installed covering 200,000 sq. ft in a diverse set of buildings
• Upper air systems were monitored at set intervals, and measured before and after cleaning
• UVC lamps were replaced when output fell below a set criteria
TB/UV Shelter Study (TUSS)St. Vincent’s Hospital and Harvard School of Public Health
Requirements for Compliance
• Design and installation by qualified professional
• Verification of occupant safety during commissioning
• Operations and Maintenance plan
Planning an Installation• Planning an installation
– Arrange meeting with facilities
operator to determine where
possible transmission of airborne
pathogens might by discussing
building usage (large congregate
settings, corridors, lobbies)
– Obtain as built plans or design
plans prior to onsite walk
through/if available upload CAD
drawings
– Walk through the facility verifying room
dimensions, usage, floor to ceiling
heights, note potential locations of units
on plan
– Look at sight lines for maximum
uninterrupted flow of UV energy
– Determine wall and ceiling surfacing
materials to plan for potential
reflectivity into the lower room
– Determine space usage, how
frequently occupied, number of
occupants and potential contact with
infectious persons.
UVGI Fixture Mounting GuidanceSource: Guidelines for Utilization of UVGI SACES
Measurement of UVGI and Relative Humidity
CommissioningUpper Room UVGI System
• Commission process inspected placement and eye level irradiance measurements with IL 254 nm selective meter
• Fixtures were adjusted if eye level exposure exceeded the 8 hr TLV for UVC 254 nm wavelength.
• UV measurements at eye level (between 5.5-6.0 ft) at compass points from each figure. Check reflective surfaces, e.g. TV’s or monitors.
• Readings incorporated into final commissioned drawings.
In Service TrainingProvide administrative and maintenance staff with overview of UVGI, its
purpose, the need for maintenance and how to avoid over-exposure when working in the upper room.
What Lessons Can Be Learned from TUSS?• Planned installations with proper commissioning and maintenance are safe.• Upper air UVGI can be applied in wide variety of buildings both existing and newly
designed• Regular maintenance and monitoring can assure critical levels of UVGI overtime.• Current UVGI louvered fixtures limit effective UVC emissions due to absorption. • Air circulation, humidity level and temperature can enhance or limit UVGI
effectiveness • precautions, signage In service training, instruction on safe operation, safety
switched and multilingual signage all are necessary
Multi-lingual Warning Signs and Symbols
Green Benefits of UVGIHigh Levels of Air Disinfection
• UVGI performance can be rated by the equivalent air exchanges of ventilation that would provide the same level of microorganism removal.
• Experimental chamber studies demonstrate high levels of air disinfection potentialSource: K. Banahan
Figure 2. Equivalent air exchanges of virus removal in a room size exposure chamber due to UVCSource: McDevitt JJ, Milton DK, Rudnick SN, First MW (2008) Inactivation of Poxviruses by Upper-Room UVC Light in a Simulated Hospital Room Environment. PLoS ONE 3(9): e3186.
GREEN: Cost Effective Compared to Alternative Airborne Infection Control Strategies
• Important Factors:• Organism susceptibility• Risk of transmission• Site characteristics: air mixing, relative humidity, occupancySource: K. Banahan
Control Strategy Present value ($) per TST conversion
Increased Ventilation $1,708Stand-alone HEPA $420
UVGI $133
Data: Hypothetical scenario with TB in waiting room (Ko, 2001)
Guidance DocumentsGroups working on UVGI Guidelines and
Standards
• US EPA (Induct, Water treatment)
• CDC/NIOSH (upper room, induct)
• International UV Association (IUVA) (all areas)
• ASHRAE (Induct and Upper room)
• IESNA (Testing , Extend RP27)
• CIE (Report 6-35 UVR Air Disinfection)
Conclusions• Multiple laboratory studies past and present show
upper room UVGI as an effective air disinfection intervention (CDC Healthcare Guidelines 2005)
• UV-C Lamp and Lamp Systems can be applied safely as environmental controls for a variety of applications
• Standard testing procedures for UV-C equipment are being developed by ANSI qualified agencies
• Tools are needed to measure UV-C fluence in practical settings (in progress)
• UV-C reflectance data for modern building surfaces and paints are being measured
Acknowledgements• Research Collaborators:
– Philip W. Brickner, MD, P.I. Mt. Sinai Hospital-New York – Melvin W. First, ScD, Harvard School of Public Health– Edward A. Nardell, MD, Harvard School of Public Health– Steven N. Rudnick, ScD, Harvard School of Public Health– Megan Murray, ScD, MD, Harvard School of Public Health– Kevin Banahan, MSc. Barclay Financial Services– Thomas Dumyahn, M.Sc., Harvard School of Public Health– William Chaisson, P.E., Chaisson Consulting, Newton, MA– Paul Minor, AIA, Chaisson Consultants, Newton, MA– Richard Riley, MD, Johns Hopkins deceased– Jonathan Freeman, MD, Harvard School of Public Health,
deceased• Sponsors
– New York State Energy Research Development Authority (NYSERDA)
– Consolidated Edison Company of New York
Questions?
THANK YOU
For further information please contact:
Richard L. Vincent, FIES, LEED® AP
212.604.6515