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How safe is UV-C light?

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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.

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

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"

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. 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 the 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 effectiveness.
 

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”

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.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 find out more about our UV-C solutions, visit cubro.co.nz/uvc

 

 

Originally published by Signify

 

  
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