On May 7, 2020 IES hosted a 3.5 hour webinar on UV Germicidal Lighting. The purpose of this page is to share and highlight some important information. As a lighting designer, I am sharing some of what I have learned, I am not giving medical advice, please consult your doctor.
UV Lighting for COVID-19 - Learning Objectives
History of Germicidal UV Light
1877 - Discovery of the ability of sunlight to prevent microbial growth. Dose = intensity + time combined with the wavelength expressed in nm and the sensitivity of the organism.
1930’s - Upper room air disinfection with measles.
1946 - Applications of Germicidal, Erythemal and Infrared Energy, Book by Matthew Luckiesh
1960’s - TB (Tuberculosis) research introduces mixing the upper room UVGI irradiated air with the lower room air.
1990's to present - Resurgence of TB encouraged more upper-room UVGI research to prevent TB transmission.
2009 - Upper-Room Ultaviolet Light and Negative Air Ionization to Prevent Tuberculosis Transmission - https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1000043
Types of UV Disinfection
Ultraviolet Dosing Terminology
2009 GUV Dosing Criteria CDC Guidelines - https://www.cdc.gov/niosh/docs/2009-105/pdfs/2009-105.pdf
Dose = intensity + time combined with the wavelength expressed in nm and the sensitivity of the organism.
Wavelength = A typical human eye will respond to wavelengths from about 380 to 740 nanometers called the visible spectrum or simply light.
Ultraviolet light is electromagnetic radiation with wavelength from 10 nm to 400 nm
nm = nanometer is the term used to describe the wavelength of a color or part of the electromagnetic spectrum. (American spelling) is a unit of length in the metric system, equal to one billionth (short scale) of a metre (0.000000001 m).
Watt - Output power of given lamp expressed in watts, not using Lux or Lumens as in visible light. Lamp radian output to effective dose rate. Lamp radian output to effective dose rate.
Duration - Exposure time.
Intensity - UV-C Irradiance measured in watts.
Air Exchange = CFM - Cubic Feet per Minute
Air, surface, or moisture require different methods.
CADR - Clean Air Delivery Rate (HVAC actual airflow rate corrected for particle removal efficiency)
ACH - Air Changes per Hour (HVAC)
Lamp - Light bulb
Luminaire - Housing, lamp, transformer or ballast, wiring assembly combined to make a complete light fixture.
Ultraviolet Light Sources
Installation & Maintenance
Reflectance for UV is different than Visible Light
Defining the use of UV effectiveness in circulating air ductworks 2002
UV 254 nm Reflectance from different materials - How is UV reflection different from Visible Light reflection? "Many surfaces reflect UV radiation and add to the overall UV levels you experience. While grass, soil or water reflect less than 10 per cent of incident UV radiation, sand reflects about 15 per cent, and sea foam about 25 per cent. Fresh snow is a particularly good reflector and almost doubles a person's UV exposure. Recurring incidences of snow blindness or photokeratitis in skiers emphasize that UV protective measures must take ground reflection into account." World Health Organization
UV Paint Finishes
An example, Sherwin Williams recommends Utilize Saniglaze wall system with the GP4410 flat urethane finish. The 4410 will be the most resistant to high UV scenarios and still hold its color and gloss.
Utilize warm colors with lower light reflectance values. Warmer colors will absorb fugitive UV where as lighter colors will reflect the UV off of its surface. [PDM, Protective Coatings Division, Sherwin-Williams Co.]
With all paints, the LRV (Light Reflectance Value) decreases as the colors become darker. Industrial Safety Colors, and Finish options and Chemical Resistance links below.
SW LRV (Light Reflectance Value) - I & M Color Chart 2003
SW Safety Colors - Corothane 2003
SW Aquarmor WBU - Water Based Urethane (Two Part)
SW Chemical Resistance Guide 2002
UV Germicidal Lighting Companies
Visible Light Disinfection
See Lighting for Healthcare page for more information.
Best online UV Germicidal Light resources - ask the experts