Ultraviolet (UV) radiation is differentiated depending on wavelength: UVA, waves from 315 to 400 nanometers; UVB, 280 to 315 nm; and UVC, 100 to 280 nm. Direct exposure to UV rays may be dangerous for people, but UV is an effective tool to inactivate viruses, germs and bacteria. In particular, the use of UVC rays in compliance with strict safety regulations has proven to be effective in sanitizing environments and surfaces. For this reason, the Italian National Institute of Health (ISS) has included such a method in the document “Interim recommendations on the sanitization of non-sanitary facilities in the current COVID-19 emergency: surfaces, indoor environments and clothing”. The document described how UVC radiation can modify the DNA or RNA of microorganisms, preventing them from reproducing and becoming noxious. For that reason, UVC is used in various applications for disinfection. In vitro studies have clearly shown that UVC light can inactivate 99.99% of an aerosolized flu virus.
Risks for users
The manufacturers of devices that emit UVC radiation must comply with strict safety parameters for users, in addition to verifying that such devices are effective for their intended purpose.
According to the ISS, UVC radiation can be used safely in closed systems to disinfect surfaces or objects where UV light does not come out. However, conventional systems with wall- or ceiling-mounted UVC lamps that generate UVC light without user-exposure protection represent a potential danger depending on wavelength, exposure intensity and duration. The danger is amplified by the fact that UVC radiation cannot be sensed by human beings because it does not convey any thermal sensation and is invisible. Therefore, the design of these devices must conform to strict safety regulations and provide for the choice of shapes and materials that suitably shield UVC rays. This is especially true for consumer devices since the user may not know the dangers related to direct exposure to UV radiation that can reach children and pets, too. Those who release these products on the market must guarantee their absolute safety. Due to the fast diffusion of such devices advertised as suitable for killing viruses and bacteria, the Ministry of Health has identified noncompliant and dangerous health hazards. According the Ministry, it is also worth highlighting that some UV lamps sold online claiming sterilizing powers against viruses and bacteria do not emit UVC rays and are therefore ineffective. Other lamps release doses of UVA, UVB and UVC rays not in conformity with European regulations that are potentially toxic.
UL empowers manufacturers to achieve efficacy and safety certifications
To educate producers on the design of safe and effective UVC appliances, UL has developed a comprehensive program that includes a series of tests and certifications. «In the current global situation, safety considerations concerning the use of lighting and UV radiation for germicidal purposes are fundamental, since numerous products based on this technology are entering the sectors of lighting, household appliances, consumer products, health care and much more», said Todd A. Straka, Director and Global Industry Leader, Lighting.
The first characteristic addressed by UL with regard to product design is containment, meaning that the product can effectively reach germs without exposing people to the radiation.
«In consumer-oriented germicidal devices, containment is obtained by positioning the UVC source inside the product body -, said Straka. – On the contrary, germicidal devices intended for use by qualified professionals in controlled environments can have exposed UVC sources. These different approaches depend on the higher risks of improper use — intentional or not — by consumers who might not follow — or understand — the safety instructions on the product or package. On the contrary, trained professionals are expected to conform to safety indications and use the necessary protection devices».
We offer training to obtain safety certification for most commercial and health UVC devices and specific types of UVC consumer devices. We can certify the safety suitability of UVC devices (180 to 280 nm = short-wave UVC) using UL Standards for the product type. Wherever the Standard does not already include photobiological safety requirements for UVC, ACGIH, ANSI/IES RP-27 or IEC 62471, standards will be applied for photobiological assessments. We provide the manufacturer with all indications to satisfy the requisites for safe use of UVC radiation, assessing the suitability of labels to warn users about exposure risks and performing a photobiological evaluation of the dangers of personal injuries connected with UVC. The safety certification concerns various hazards, such as electric shock, fire and personal injury, but they do not attest to the level of product efficacy. We have developed a specific program to test and check the solution’s overall effectiveness, measuring the reduction of bacteria, viruses or spores over time. The program helps demonstrate product performance for the disinfection of air or surfaces in a reliable and repeatable manner.
