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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.

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


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

Using UV light for disinfection is well-established. UVC light inactivates airborne and surface pathogens like viruses and bacteria by damaging their RNA and DNA.

Conventional germicidal lamps emit UVC light with longer wavelengths (>230nm) that also effectively reduce airborne and surface pathogens but present a human health hazard to unprotected eyes and skin.

What’s new is the discovery and application of far-UVC 222nm light, a sweet spot on the UV spectrum, than can effectively inactivate pathogens with people present without the need for protective gear. When filtered to prevent harmful longer UVC wavelengths (>230nm) from being emitted, it’s safer for use in occupied spaces and allows for automated, continual pathogen-reduction.

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


Is far-UVC 222nm light the solution?

Ushio Inc.’s patented Care222® Krypton-Chloride (KrCl) excimer lamp modules produce filtered far-UVC 222nm light that’s safer for humans: its limited range of penetration means it’s unable to deeply penetrate the protective outer layers of our skin and eyes.

The far-UVC 222nm light Care222 technology emits provides an added layer of defense against pathogens like the SARS-CoV-2 coronavirus that causes COVID-19 and antibiotic-resistant bacteria such as MRSA (Methicillin-resistant Staphylococcus aureus) and E. coli (Escherichia coli).

The disinfection technology we need right now

Christie® CounterActcommercial UV disinfection fixtures contain patented Care222® technology that continuously emits filtered far-UVC light that’s designed to neutralize pathogens with people present while meeting established safety guidelines. Care222 is also the world’s first UVC technology with a proprietary optical filter that blocks potentially harmful UVC wavelengths from being emitted.

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 U.S. Food and Drug Administration and the U.S. 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 American Conference of Governmental Institutional Hygienist (ACGIH) guidelines.

Professional installation is recommended for Christie CounterAct products.

“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.