UVC Dosage for Disinfection: Six Steps

Written by Cameron Dillehay | May 6, 2020 1:22:19 PM

Viruses, bacteria, mold, and other pathogens are now stopped dead in their tracks with XtraLight's UVC High Power Ultraviolet Disinfection System. Follow these steps when using this effective and powerful light which emits 254 nm wavelengths. The results will amaze you and give you peace of mind.

UVC STEPS TO DISINFECTION:

STEPS:

FOLLOW SAFETY GUIDELINES
UNDERSTAND BASIC UVC TERMS
IDENTIFY UV DOSE
SURVEY AREA TO BE DISINFECTED
CALCULATE ESTIMATED UV EXPOSURE TIME FOR DISINFECTING
DISINFECT AREA AND VALIDATE WITH DOSIMETER CARDS

All surfaces within a certain distance will observe an assured level of disinfection in a certain amount of time as long as the wavelengths are not blocked from accessing the surface.

STEP 1

FOLLOW SAFETY GUIDELINES

Do's

Don’t's

Protect your eyes
Use protective PPE gear
Establish a plan to disinfect area
Use safety timers
Train personnel in using UVC disinfecting system
Use hazard warning signs when in use
Keep fixture in protective case

Don’t expose eyes & skin to UVC
Don’t allow anyone to operate UVC fixture without reading safety instructions
Don’t allow anyone into area being treated with UVC
Don't touch the UVC lamps while operating

Excessive exposure to UVC can cause adverse effects on the eyes, retina, skin, circadian system, and immune system.
Human over exposure causes temporary skin redness and harsh eye irritation.
Symptoms may take 4 to 24 hours to occur after exposure.

STEP 2

UNDERSTANDING BASIC UVC TERMS

RADIANT EXPOSURE = J/m² or mJ/cm²

UV INTENSITY (I) = energy per unit surface area
EXPOSURE TIME (T) = exposure time in seconds
UV DOSE (FLUENCE) = Intensity (I) x Time (T) expressed as mJ/cm²

LOG REDUCTION = percentage of microorganisms inactivated

EXAMPLE:
a 1 log reduction will reduce the pathogen by 90%, before the UVC disinfection
a 2 log reduction will reduce the pathogen by 99%, etc…

STEP 3

IDENTIFY UV DOSE

IDENTIFY TARGETED MICROORGANISMS

PAIR WITH LOG REDUCTION.

PATHOGENS	Common Name	Scientific Name	3 Log Reduction
Viruses	Rota	Rotaviruses (Human)	32 mJ/cm2
	Infectious Hepatitis	Hepatitis B	25 mJ/cm2
	Adenovirus		126 mJ/cm2
	ECHO Virus	Echovirus	25 mJ/cm2
Bacteria	Salmonella	Salmonella Typhimurium	22 mJ/cm2
	Staph	Staphylococcus aureus	3.2 mJ/cm2 (2 log)
	Strep	Streptococcus faecalis	9.8 mJ/cm2

UV dose determines what proportion of a specific microorganism is destroyed after a particular dose of UV radiation

Target 50 mJ/cm2 to deactivate the average bacteria/virus
Example from Log Reduction

Example from Log Reduction

STEP 4

SURVEY AREA TO BE DISINFECTED

MEASURE DIMENSIONS OF AREA TO BE DISINFECTED USING MOBILE UNIT
TARGET UV DOSE is 50 mJ/cm²
PLACE DOSIMETER CARDS ON TARGETED AREAS FOR VALIDATION OF UV DOSE

Our testing Data:

XLM Product	UV Intensity	Exposure Time	Radiance Exposure	Distance
Handheld	2.8 mJ/cm²	17 sec	50mJ/cm²	4 in.
Mobile	.34 mJ/cm²	6 min	50mJ/cm²	5 ft
Mobile	.08 mJ/cm²	17 min	50mJ/cm²	10 ft
Mobile	.03 mJ/cm²	28 min	50mJ/cm²	15 ft

STEP 5

CALCULATE ESTIMATED EXPOSURE TIME FOR DISINFECTING

DETERMINE PLACEMENT OF MOBILE UNIT AND NUMBER OF UNITS TO DISINFECT AREA
CALCULATE EXPOSURE TIME = UV INTENSITY (at a specified distance) / UV DOSE / 60 SECONDS
UV DOSE = 50 mJ/cm²

STEP 6

DISINFECT AREA AND VALIDATE WITH DOSIMETER CARDS

Color changes from yellow to orange validates 50 mJ/cm² delivered
Color changes for orange to pink validates 100 mJ/cm² delivered
Exit the room and run disinfection cycle
Verify exposure of card and make notations on the card to document the color change
Make exposure reading within 24 hours after disinfection
Retain or discard the card in accord with site requirements
1 time use of dosimeter cards

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To learn more about UV disinfection click here

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