April 8, 2021
Like many scientific discoveries, the journey to modern UVC (200 -280 nm) disinfection started with an observation. In 1877, British physiologist Arthur Downes and scientist Thomas P. Blunt noticed that sunlight inactivates the development of pathogenic bacteria. Through additional research, Downes and Blunt eventually discovered that the violet-blue spectrum of light was most effective in eradicating bacteria, according to an article published by IEEE Spectrum in August 2020.
For UVC disinfection purposes, one fact always needs to be taken into account: areas that are shadowed or not reached by the radiation will not be disinfected. However, UVC can be understood as an efficient, environmentally friendly, chemical-free technology that supports our efforts to control any kind of disease or pandemic, not only COVID-19.
But UVC can be harmful to humans, causing damage to skin and eyes. Therefore, it is not appropriate to disinfect people’s hands or faces, and UVC devices should not be used without appropriate safeguards, training and personal protection equipment.
Standards help people understand whether a product is safe for use by the general public. In North America and other regions, the standards reference IEC 64271, Photobiological safety of lamps and lamp systems. According to IEC 62471, a photobiological risk assessment should be performed for all UVC light sources.
Manufacturers of household and similar electrical appliances, such as air-conditioners with UVC function, can find the related requirements in IEC 60335-2-40 and in IEC 60335-2-65. But first, the general requirements need to be fulfilled. Annex T of IEC 60335-1 formulates a UVC exposure test for all nonmetallic materials (in this case, plastics). The relevant Part 2 requires an additional test of the whole appliance to demonstrate that non-visual emitted UVC light is within the allowed limits. For luminaire type devices, EN 60598 (based on IEC 60598) is the applicable standard for Europe. For North America, the Standard is UL 1598, the Standard for Luminaires.
At this point we would like to refer also to our webpage https://www.ul.com/services/ultraviolet-uvc-light-testing-and-certification. The number of different applications and designs is too large to discuss in detail, but this webpage is definitely a perfect starting point for a discussion. The table of UVC product types in the webpage provides an overview of the standards that are applicable and whether a product safety certification by UL is possible.
But what does this mean for the germicidal functionality of the appliance? Product manufacturers, as well as the end users, must know that UVC light solutions are safe and effective. The standards mentioned in this article help demonstrate product safety to protect the end users. In addition to the safety aspects, We developed a program to test and verify the overall solution effectiveness by measuring the bacteria, virus or spore reduction over time. The program helps to demonstrate product performance of air or surface disinfection in a reliable and reproducible way.