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Ultraviolet Light Exposure Dosage

The degree of inactivation by ultraviolet radiation is directly related to the UV dose applied. The UV dose is the product of UV intensity [I] (expressed as energy per unit surface area) and exposure time [T].

Therefore: DOSE = I x T

This dose, sometimes referred to as fluence, is commonly expressed as millijoule per square centimeter (mJ/cm2). The units "J/m2" are used in most parts of the world except for North America, where "mJ/cm2" are used.

The reduction of micro-organisms is classified using a logarithmic scale. A single log reduction is a 90% reduction of organisms. A two log reduction is a 99% reduction of organisms, followed by a three log reduction (99.9%), etc. The UV-C exposure dosage needed for each level of reduction is shown in the table along with the published reference where the data came from.

Persistence of Bacteria

Persistence Bacteria On Dry Inanimate Surfaces
Organism Persistence
Acinetobacter spp.3 days to 5 months
Bordetella pertussis3-5 days
Campylobacter jejuniUp to 6 days
Clostridium difficile (spores)5 months
Chlamydia pneumoniaeUp to 6 days
Chlamydia psittaci5 months
Chlamydia pneumoniaeUp to 30 hours
Chlamydia psittaci15 days
Corynebacterium diphtheria7 days – 6 months
Corynebacterium pseudotuberculosis1-8 days
Escherichia coli1.5 hours – 16 months
Enterococcus spp. including VRE and VSE5 days – 4 months
Haemophilus influenza12 days
Helicobacter pyloriUp to 90 minutes
Klebsiella spp.2 hours – 30 months
Listeria spp.1 day – 4 months
Mycobacterium bovisUp to 2 months
Mycobacterium tuberculosis1 day – 4 months
Neisseria gonorrhoeae1-3 days
Proteus vulgaris1-2 days
Pseudomonas aeruginosa6 hours – 16 months; 5 weeks on dry floor
Salmonella typhi6 hours – 4 weeks
Salmonella typhimurium10 days – 4.2 years
Salmonella spp.1 day
Serratia marcescens3 days – 2 months; 5 weeks on dry floor
Shigella spp.2 days – 5 months
Staphylococcus aureus, including MRSA7 days – 7 months
Streptococcus pneumoniae1-20 days
Streptococcus pyogenes3 days – 6.5 months
Vibrio cholera1-7 days

*The data table above was compiled by research on Google and Bing. We cannot confirm that the data is accurate, but only that it come from reputable websites, renoun scientists, labs and research centers around the world.

Independent research & development...

We compiled several links to studies made by top scientists, virologist and UV lighting experts around the world. Their work contributed to many major breakthroughs in UV lighting sterilization technologies and disinfection processes in a multitude of applications, including air, water and surface treatments using UVC lighting.


References

Evaluation of an Ultraviolet C (UVC) Light-Emitting Device for Disinfection of High Touch Surfaces in Hospital Critical Areas at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6801766/

UVC LED Irradiation Effectively Inactivates Aerosolized Viruses, Bacteria, and Fungi in a Chamber-Type Air Disinfection System at https://aem.asm.org/content/84/17/e00944-18#:~:text=UVC%20light%20is%20well%20known,materials%20(16%2C%2017).

Welch, D., Buonanno, M., Grilj, V. et al. Far-UVC light: A new tool to control the spread of airbornemediated microbial diseases. Sci Rep 8, 2752 (2018). https://doi.org/10.1038/s41598-018-21058-w

Tseng, CC, Li, CS. (2007). Inactivation of viruses on surfaces by ultraviolet germicidal irradiation. Journal of Occupational and Environmental Hygiene, 4(6): 400-5. Retrieved from https://www.tandfonline.com/doi/full/10.1080/15459620701329012

Nature of UV. (n.d.). Retrieved from American Air and Water at https://www.americanairandwater.com/uv-facts/uv-light.htm

Crosta, P. (2017). What to know about viruses. Retrieved from Medical News Today at https://www.medicalnewstoday.com/articles/158179

Krug, R. M. & Wagner, R. R. (2020). Virus: General Features, Definition. Retrieved from Encyclopedia Britannica at https://www.britannica.com/science/virus

Silverman, J. & Kiger, P. J. (2020). How Can Light Kill Viruses? Retrieved from How Stuff Works: Science at https://science.howstuffworks.com/life/cellular-microscopic/light-virus1.htm

UV Basics: How UV Disinfection Works (n.d.). Retrieved from Trojan UV at https://www.trojanuv.com/uv-basics?acceptCookies=1

Crosta, P. (2017). What to know about viruses. Retrieved from Medical News Today at https://www.medicalnewstoday.com/articles/158179

Geiger, D. (2020, April 28). UV Light Helps Duke Hospitals Fight Transmission of Superbugs. Retrieved from Duke Health website at https://www.dukehealth.org/blog/uv-light-helps-duke-hospitalsfight-transmission-of-superbugs

Mishra, M. (2019, December 4). UV lights in hospitals could help limit bacteria on phones. Retrieved from Reuters website at https://www.reuters.com/article/us-health-hospitals-uv-sanitizers/uvlights-in-hospitals-could-help-limit-bacteria-on-phones-idUSKBN1Y82L4

Tseng, CC, Li, CS. (2007). Inactivation of viruses on surfaces by ultraviolet germicidal irradiation. Journal of Occupational and Environmental Hygiene, 4(6): 400-5. Retrieved from https://www.tandfonline.com/doi/full/10.1080/15459620701329012

Ultraviolet and HVAC: Keys to reducing hospital acquired infections. (n.d.). Retrieved from Hospital News website at https://hospitalnews.com/ultraviolet-hvac-keys-reducing-hospital-acquiredinfections/

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