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The History of Ultraviolet Germicidal Irradiation

The History of Ultraviolet Germicidal Irradiation

The history and research studies on UV-C have always been closely intertwined with public health threats. This continued research has brought about the evolution of the effectiveness, accessibility, and applications of UV-C.

The way UV-C disinfects is a fairly simple concept. UV-C photons penetrate the cell wall, disrupt the DNA, then leave the virus or bacteria inactive (aka “killed”), unable to replicate.

You can apply this technology to kill germs in the air or on surfaces in your home or business at multiple affordable price points. At UV CAN Sanitize, our top-selling Tulip 2 and Cosmos Wall Mount air purifiers are not only equipped with a HEPA filter and activated carbon filter, but also germicidal UV-C lights that inactivate (aka, “kill”) viruses and bacteria, reducing their concentration in the air indoors.

Tulip 2 UV Air Purifier

 Cosmos Wall Mount UV Air Purifier

Tulip 2 is the best portable air purifier for your home or your desk in the office as it disinfects and purifiers the air at a rate of 2,472 to 3,885 ft³ per hour.

Cosmos Wall Mount disinfects at a rate of 35,300 ft³ per hour making it best for your large office space, boardroom, waiting room,  or reception area.

We at UV CAN are excited and proud to be part of the next era of disinfection technology: UV-C. Keep reading below to learn about and familiarize yourself with how far we have come as an industry and key developments.


1877 Discovery that sunlight can hinder microbial growth

Downes and Blunt discovered that sunlight can prevent bacterial growth. This led to later findings that its effectiveness depends on the UV’s radiation wavelength, the dose (intensity x time), and how sensitive the particular microbe is to UV.


1930 R. L. Gates publishes the first study on the bactericidal action of ultraviolet light

Gates introduces the bactericidal action spectrum, which most people in the UV industry refer to as the germicidal range today. This disproved the assumption that the shorter the wavelength, the more effective against germs. He found that the most lethal UV wavelengths are between 260 and 270nm, with the peak at 265nm. This is very close to the 254nm output of today’s low-pressure mercury germicidal lamps and 260-280nm UV-C LEDs.


1934 W.F. Wells introduces the concept of airborne disease transmission

Researchers before W.F. Wells were aware of disease spread through droplets from coughing and sneezing. However, W.F. Wells proposed the idea of droplet nuclei – which are evaporated droplets from the infected person that continue to hang in the air and spread disease.


1942 W.F. Wells publishes research showing that upper-room UV reduces airborne disease transmission in classrooms

The experiment involved public schools in Philadelphia during the 1940s and 1930s. W.F. Wells, M.W. Wells, and Wilder’s findings supported their hypothesis: “epidemic contagion is spread through the medium of confined atmospheres and can be prevented by radiant disinfection of air.” They suggested applications for schools in winter when children are most at risk, and for overcrowded army barracks.


1957 R. L. Riley proves UV-C to be effective for Tuberculosis control using in-duct UVGI systems

Riley conducted experiments on guinea pigs to prove that TB was an airborne disease. He compared 2 groups of guinea pigs, one breathing air from an occupied TB ward with an Ultraviolet Germicidal Irradiation (UVGI) system installed in the duct, the other with no UVGI system installed in the duct. The guinea pigs breathing contaminated air from the UVGI-equipped duct did not get infected with TB, while the group breathing contaminated air from the non-UVGI duct did get infected.


1994 CDC acknowledges UV-C’s effectiveness for TB control to protect healthcare workers

 There was an unexpected resurgence of TB in the United States from the mid-1980s through the early 1990s. In response, the CDC released a document updating healthcare facility guidelines acknowledging upper room UVGI’s effectiveness against TB. This was done to protect healthcare workers.


1997 UV research picks up again due to TB’s resurgence during the mid-1980s to early 1990s

The CDC contracted the University of Colorado to conduct research on the effectiveness of a well-designed upper room UVGI system. They controlled many parameters such as: the dose needed to inactivate TB, best way to measure UV-C doses, effects of air mixing on the system’s performance, relationships between mechanical ventilation and UVGI systems, effects of photoreactivation (PR) and humidity, and the best placement of UVGI fixtures. They discovered that a well-designed UV disinfection system may inactivate airborne TB bacteria and protect healthcare workers.


1999 WHO recommends UVGI to prevent TB transmission

WHO released “Guidelines for the Prevention of Tuberculosis in Health Care Facilities in Resource-Limited Settings.” They recommended UVGI as an additional environmental control to reduce airborne transmission of TB through aerosolized droplets from infected people. WHO specifically recommended continuous upper room UV-C disinfection for large wards, TB patient waiting rooms, and TB patient recreation rooms.


2014 UV-C is used as part of the rigorous terminal cleaning procedures upon Ebola patient discharge

Terminals such as the Nebraska Biocontainment Unit used UV-C disinfection as part of their terminal cleaning procedure after discharging Ebola patients. This was to protect healthcare workers and prepare the area for future patient care. This Technical Information Paper called “Terminal Cleaning for Ebola Virus Disease Contaminated Patient Care Areas” states “The UV-C light deactivates bacteria, viruses, and spores. This treatment option is relatively quick, repetitious, and leaves no residue.”


2020 COVID-19 pandemic spurs renewed interest and implementation of UV-C technology

Based on empirical evidence and available disinfection data, organizations such as the International Ultraviolet Organization (IUVA) believe that UV-C systems can effectively play a part to reduce transmission of the virus, SARS-CoV-2, alongside other disinfection methods. We now know that all known viruses and bacteria respond to UV at appropriate doses. Also, UV-C is demonstrated to inactivate (AKA kill) at least two other closely related coronaviruses, SARS-CoV-1 and MERS-CoV.


UV has been studied and used for disinfection for over 80 years. If you are looking to incorporate this technology as an extra preventative measure against dangerous pathogens, such as the virus causing COVID-19, check out our UV air purifiers, Tulip 2 and Cosmos Wall Mount for your home or workplace respectively.

You can get a free consultation with UV CAN’s industry experts about how to best incorporate UV into existing disinfection and sanitization routine. Either email info@uv-can.com with the subject line, “Free Consultation” to start booking a time or call our office at 604-423-5599.

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