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UV disinfection

Using physics to solve a biological problem

Could ultraviolet light be an effective solution?

Ultraviolet (UV) light is a proven disinfectant against harmful viruses, bacteria, molds, and spores. As part of the electromagnetic spectrum, it’s invisible to the human eye and has the power to break down the RNA and DNA of viruses and bacteria so they can no longer reproduce or infect us. UV light can be used to disinfect air, surfaces, and water.

Germicidal UV light disinfection uses ultraviolet C, or UVC, light to reduce pathogens—including viruses and bacteria—in the air, on surfaces, and even in water.

Let’s start with a quick look at UV light.

Did you know?

The earliest research paper describing using UVC light to sterilize bacteria was published in 1978. The 1903 Nobel Prize for Medicine was awarded to Niels Finsen for his use of UV against tuberculosis of the skin. And using UV light for disinfecting drinking water dates back to 1910 in Marseilles, France.


UVA, UVB, and UVC: What’s the difference?

The ultraviolet spectrum of light is made up of 3 bands: UVA, UVB and UVC.

This graphic illustrates the 3 types of ultraviolet light the sun produces: UVA, UVB, and UVC

This graphic illustrates the 3 types of ultraviolet light the sun produces: UVA, UVB, and UVC



Around 95% of the sun’s rays that reach the ground are UVA rays. They have the longest wavelengths and can damage our skin, causing premature aging such as wrinkles and are thought to play a role in some skin cancers.


UVB rays make up around 5% of the sun’s rays, and while they don’t penetrate our skin as deeply as UVA, they can cause significant damage to our skin, including redness, sunburn, and skin cancer. We use sunscreen and wear sunglasses to protect our eyes and skin from both UVA and UVB rays.


Most UVC rays don’t reach the earth’s surface because they’re absorbed by the ozone layer.

Not all UVC light is created equal

Traditional UVC light is proven technology—since scientists in the late 1800s first started investigating the power of sunlight to prevent the spread of airborne infections to today where it’s used in commercial disinfection systems.  Care222 filtered far-UVC light technology—with its sweet spot on the UV spectrum, can safely and continuously inactivate airborne and surface pathogens when people are present because of the filter that removes longer, harmful wavelengths.

These 2 UV disinfection technologies are combined in a way that is safe for occupied spaces: Ushio’s filtered Care222® far-UVC light to inactivate airborne and surface pathogens plus upper room UVC to inactivate airborne pathogens in the upper room space.

The disinfection technology we need right now

UThe first-ever technology to combine upper room UVC and far-UVC surface disinfection, CounterAct UR10 fixtures sit below the ceiling to continually disinfect the air in the room as it moves through the space adjacent to the ceiling, while also continually providing surface disinfection that is safe to use in the presence of people. 

Read about far-UVC light »

Far-UVC 222nm: The disinfection technology we need now and for the future


UV disinfection:  Feel protected, feel normal.

Care222 filtered far-UVC light has a shorter wavelength that’s unable to deeply penetrate the protective outer layers of our skin and eyes, so it can effectively and continuously inactivate airborne and surface pathogens around people. Traditional germicidal UVC is >230nm and has longer wavelengths that are extremely effective against pathogens, however exposure can damage eyes and skin if unprotected. Put these 2 technologies together with Christie® CounterAct UR10, and you get enhanced, continual disinfection of both air and surfaces in indoor spaces that lets you feel protected, feel normal in the places we gather.

Find out more about Christie CounterAct »

UV disinfection products

Related resources

All references to “disinfect”, “disinfecting”, and “disinfection” refer generally to the reduction of pathogenic bioburden and are not intended to refer to any specific definition as may be used by any governmental or regulatory authority, including the US Food and Drug Administration and the US Environmental Protection Agency. Christie CounterAct products with patented Care222 technology are not medical devices and are not to be used as or for medical devices. The pathogen-reducing efficacy of Christie CounterAct products and their use in occupied spaces is dependent on many site-specific factors as well as proper installation and operation within specifications and in accordance with the American Conference of Governmental Institutional Hygienists (ACGIH) guidelines. Professional installation is recommended for Christie CounterAct products. Ushio’s Care222® filtered Far UV-C technology (“Care222 Technology”) is protected under US and non-U.S. patents covering apparatuses and methods for inactivating viruses or killing bacteria with combinations of a light source and an optical filter that block potentially harmful UV-C wavelengths. Inventions in these patents are credited to Dr. David Brenner, et al., and assigned to Columbia University. Ushio Inc. is the worldwide exclusive licensee of these patents. “Christie” is a trademark of Christie Digital Systems USA, Inc., registered in the United States of America and other countries. This product uses Care222® technology developed by Ushio Inc. The Care222® is a trademark or registered trademark of Ushio Inc. and Ushio America, Inc.