UV-C and safety


    August 25, 2020


    UV-C can deactivate the virus that causes COVID-19. But how safe is it?


    As the world comes to terms with the first great global pandemic of our age, technology like UV-C disinfection lighting will play an ever more important part in our future.

    We’ve talked about UV-C in our blog and social media in recent months and we’ve received one question more than any other: is it safe? So, in response, here’s a quick breakdown of how UV-C works and how it can be used in an effective and safer way to keep our shared spaces disinfected and hygienic.

    How UV-C disinfection works

    Signify’s UV-C products use ultraviolet light to inactivate microorganisms like viruses and bacteria, making them harmless to humans. UV-C disrupts the DNA or RNA that enables those viruses and bacteria to multiply. It’s been used safely and effectively for more than 40 years.
    Sunshine – generic library

    UV-C is found in nature

    There are three type of UV radiation found in sunlight. There’s UV-A and UV-B, which you may recognize from sunscreen labels. UV-A and UV-B cause sunburn and signs of skin ageing like wrinkles and age spots, and even skin cancer.

    We don’t come into contact with UV-C because it is filtered out by the ozone layer in the Earth’s atmosphere. The wavelength of UV-C light is shorter than the wavelength of the light we can see and spans the range of 100-280 nanometers (nm). It is most effective at inactivating viruses on or around 260-265nm, known as the ‘germicidal peak’. Signify’s UV-C lamps operate at 254nm, which is proven to be highly effective in inactivating viruses, bacteria and mold spores.

    Humans and animals should not be exposed to germicidal UV-C light at this wavelength as it can cause damage to their skin and eyes in a matter of minutes1 of exposure. That said,  provided that our UV-C products are used and installed correctly and in accordance with our user manuals and mounting instructions, UV-C is a reliable and highly effective form of disinfection, with safety risks mitigated by the appropriate safeguards put in place.

    Professional use

    Signify’s professional UV-C products are not available for use and/or purchase by consumers. They are designed and intended to be used by trained professionals who take the appropriate safety precautions.

    A combination of good product design, implementation of appropriate safeguards, training and instructions for users and installers, provide additional layers of safety for our UV-C products.

    UV-C disinfection with people in the room

    UV-C disinfection in the room
    Signify also brings solutions in which UV-C radiation at 254nm is safe to use with people in the room. Our upper air disinfection systems are designed to allow people to be present underneath them during their operation. These systems are installed high up in the room and disinfect air through natural convection as it passes through a well-controlled and narrow UV-C irradiated zone that remains close to the ceiling. This zone is at a height above where people are typically present. The systems are positioned at least 2.3 meters off the floor and have shielding to ensure people underneath them are not exposed to the UV-C light source.

    Our upper air disinfection systems are designed to allow people to be present underneath them during their operation”

    People can also be in a room when using our UV-C chambers to disinfect objects2. A good example is the Once BioShift chamber, which looks a bit like an industrial microwave oven. Items are placed inside the chamber for treatment. The UV-C radiation is completely contained inside the chamber in the same way that microwaves are absorbed inside a microwave oven.


    Where safety precautions are needed is during direct exposure of surfaces to a UV-C light source. This is the case, for example, with the disinfection of surfaces in an office or a bus. To prevent damage to eyes or skin resulting from direct exposure to UV-C light sources, no people or animals can be present during a UV-C surface disinfection cycle. That’s why surface disinfection cycles are typically run at night after all people have left the office or after the bus returns to the depot.

    Disinfection of surfaces
    And whilst UV-C light cannot pass through protective surfaces, including windows, extra levels of safety can be provided by sensors that can switch the UV-C light sources off if they detect people or animals.

    Safety standards

    The COVID-19 pandemic has accelerated the development and use of UV-C disinfection products across the globe. With that in mind, it’s essential that companies involved in the production and roll-out of germicidal UV-C lighting adhere to the highest safety standards. The Global Lighting Association has developed guidelines for manufacturers and users of UV-C disinfection products that focus on increasing the safety of products for their users. Signify’s UV-C products are developed and designed to meet the high standard set by this new guidance.

    Far UV-C

    UV-C light with a shorter wavelength (in the range of 207 – 222nm) is sometimes known as Far UV-C. Far UV-C light can’t penetrate the cells of our skin. It can inactivate drug-resistant bacteria, without apparent harm to the skin and eyes of mammals, so it has potential to be used to disinfect areas where there are people. However, further research and tests will reveal the full extent of its safety and effectiveness4.

    UV-C’s effectiveness as a disinfectant

    All micro-organisms that have been tested so far for UV-C exposure were shown not to be resistant to
    UV-C light”

    Boston University tested Signify germicidal UV-C

    UV-C is very effective. All micro-organisms that have been tested so far for UV-C exposure were shown not to be resistant to UV-C light. Additionally, Boston University recently tested Signify germicidal UV-C light sources on SARS-CoV-2, the virus that causes COVID-19. The team applied a dose of 5mJ/cm2, resulting in a reduction in the virus of 99% in 6 seconds. Based on the data, it was determined that a dose of 22mJ/cm2 will result in a reduction of 99.9999% in 25 seconds.3

    To further eliminate the risk of infection, UV-C should be used in combination with other disinfection methods like traditional scrubbing using chemical disinfectant.  In high contact areas such as a gym, restroom or hospital treatment room, such additional safeguards ensure that areas that are shaded from the reach of the UV-C light are also disinfected.

    There are instances where UV-C can be applied where other methods of disinfection can’t”

    Equally, there are instances where UV-C can be applied where other methods of disinfection can’t. For example, it’s very useful for disinfecting drinking water, or objects like mobile phones that can’t be submerged in liquids.

    To sum up…

    In a nutshell, germicidal UV-C lighting is a powerful and quick form of disinfection, and by ensuring that the appropriate safeguards are put in place and that users and operators are well-instructed and trained, UV-C disinfection is a recognized and well-established means of disinfection.


    To learn more about UV-C disinfection lighting, please see our UV-C information page.


    1 Timing depends on the power of the UV-C source and proximity of the person to it. For most applications it is 1-2 minutes, although it can be shorter.

    2 Other than medical devices.

    3 The time it takes to disinfect depends on the power of the UV-C source and proximity to it. Disinfection times may therefore vary taking into account these parameters.

    4 As of today, there is yet no scientific data available on the long term effects of direct exposure of people and/or animals to Far UV-C irradiation, so it can’t be said at this moment that Far UV-C is safer than UV-C. 

    About the author:

    Neil Pattie

    Neil Pattie


    Head of Corporate Content, Signify

    Annie McFarlane

    Annie McFarlane 



    For further information, please contact:

    Signify Global Integrated Communications
    Neil Pattie
    Tel: + 31 6 15 08 48 17

    About Signify


    Signify (Euronext: LIGHT) is the world leader in lighting for professionals, consumers and the Internet of Things. Our Philips products, Interact systems and data-enabled services, deliver business value and transform life in homes, buildings and public spaces. In 2023, we had sales of EUR 6.7 billion, approximately 32,000 employees and a presence in over 70 countries. We unlock the extraordinary potential of light for brighter lives and a better world. We have been in the Dow Jones Sustainability World Index since our IPO for seven consecutive years and have achieved the EcoVadis Platinum rating for four consecutive years, placing Signify in the top one percent of companies assessed. News from Signify can be found in the Newsroom, on X, LinkedIn and Instagram. Information for investors is located on the Investor Relations page.

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