E-mail: Richard.Vincent@mountsinai.orgMount Sinai Medical Center

Community Medicine36 7Th Avenue, NY NY 10011

(212) 604‐6515

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

Richard.Vincent@mountsinai.org

212.604.6515