Answered by the technical team at RayVio corporation.

Ultraviolet (UV) light has been used for many years in industry and in health and hygiene regimes. A new generation of LEDs now looks set to challenge conventional UV fluorescent sources. But how well do they actually perform?

What is the wavelength range of UVC LEDs?

UVC LEDs are typically defined as having a wavelength on the electromagnetic spectrum of 200nm to 280nm.

What is the ‘germicidal range’ of ultraviolet light?

According to the International Ultraviolet Association:  “The portion of the UV spectrum (the ‘germicidal’ region) that is important for the disinfection of water and air is the range that is absorbed by DNA (RNA in some viruses). This germicidal range is approximately 200-300nm.”  

The germicidal range is known to extend beyond 280nm and is now generally thought to extend to 300nm, although this too may change with more research. Scientists have proved that wavelengths between 280nm and 300nm are germicidal and can be used for disinfection and sterilization.

What is the optimum wavelength for disinfection?

There is a misconception that 254nm is the optimum wavelength for disinfection because the peak wavelength of a low-pressure mercury lamp (simply determined by the physics of the lamp) is 253.7nm. A wavelength of 265nm is generally accepted as the optimum as it’s the peak of the DNA absorption curve. However, disinfection and sterilization occur over a range of wavelengths.

UV mercury lamps have been considered the best choice for disinfection and sterilization. Why is that?

Historically, mercury lamps have been the only option for disinfection and sterilization. With UV LED technology advances, there are new options that are smaller, more robust, toxin-free, long lived, energy efficient and allow for infinite on/off switching. This allows solutions to be smaller, battery powered, portable and with instant full light output.

Spectral emittance of low-pressure mercury UV lamp (solid line) and medium-pressure mercury UV lamp (dashed line)

How do the wavelengths of UVC LEDs and mercury lamps compare?

Low pressure mercury lamps emit an almost monochromatic light with a wavelength of 253.7nm. Low-pressure mercury lamps (fluorescent tubes) and high-pressure mercury lamps are also used for disinfection and sterilization. These lamps have a much broader spectral distribution that includes germicidal wavelengths. UVC LEDs can be manufactured to target very specific and narrow wavelengths. This allows solutions to be tailored to the particular application need.

Are the DNA peak absorption wavelengths different depending on the germ?

Yes, peak absorption rates do vary from germ to germ, though most are around 265nm.

Can a single wavelength be used to disinfect for all germs?

Yes, a single wavelength can be used. However, germs have different optimum absorption wavelengths.

How is germicidal effectiveness determined?

Power intensity, wavelength and exposure duration are typically used to determine germicidal effectiveness. For instance, in water there may be multiple germs with different optimal absorption wavelengths. For any given wavelength of germicidal UV light, the power and duration of exposure would need to be calculated in order to achieve the desired level of disinfection.

Are there different levels of disinfection or effectiveness?

Yes, there are actually six levels of disinfection based on the reduction factor. If we start with a population of one million bacteria, one would measure disinfection effectiveness as follows:

Reduce the colony to 100,000 bacteria – 90 per cent reduction

Reduce the colony to 10,000 bacteria – 99 per cent reduction

Reduce the colony to 1,000 bacteria – 99.9 per cent reduction

Reduce the colony to 100 bacteria – 99.99 per cent reduction

Reduce the colony to 10 bacteria – 99.999 per cent reduction

Reduce the colony to one bacterium – 99.9999 per cent reduction.

For further information see the US Environmental Protection Agency’s ‘Ultraviolet disinfection guidance manual for the final long term 2 enhanced surface water treatment rule’.

BALTIMORE, March 10, 2020 – Power Up (https://www.powerupconnect.com/) recently unveiled its newest product, the Pure Zone Antimicrobial Protection Charging Station (Pure Zone Charging Tower) intended for use by the hospitality and healthcare industry, and in other public spaces. The Pure Zone station comes with anti-microbial engineering, a Purell® dispenser with data-collection capability. The Pure Zone Charging Tower is the latest in a line of cutting-edge charging stations and technology pioneered by Power Up, which has manufactured charging stations since 2008, working to bring safe, efficient energy to users everywhere.

“Some of the latest information we’re receiving from experts confirms that cell phone users should be disinfecting their phones to help limit the spread of a wide variety of pathogens, including the coronavirus,” said Ryan Doak Co-Founder of Power Up. “But unfortunately, there is a right way and a lot of wrong ways to do this. We’ve all seen people trying to disinfect their phones, but using alcohol and swabs directly on devices will damage and ruin their screen-protection layers. Ultimately, it actually allows germs to stick to the surface even easier. So that’s why the Pure Zone station uses a tray coated with antimicrobial film. It reduces 99.99 percent of bacteria, while the Purell® dispenser helps combat the spread of viral agents.”

Pure Zone Charging Station Features

Made from hypo-allergenic, stainless steel, the Pure Zone charging tower is durable and easy to clean, making it the perfect choice for high traffic areas. The main servicing tray is coated with an antimicrobial film that reduces 99.99 percent of bacterial agents including e. coli, salmonella, listeria, golden staph, MRSA and pseudomonas aeruginosa (main culprit behind a wide range of nosocomial infections in hospital settings, like UTIs and pneumonia). Other features of the Pure Zone charging station include:

The Purell® Smartlink™ Integrated Monitoring System is an electronic hand hygiene monitoring solution that delivers volumes of reliable data to capture hand hygiene events in real time. It requires no existing location tracking infrastructure and can be enabled for nurse call and asset tracking in the future as desired. The station provides actionable data, customizable reporting and expert clinical support.

About Power Up

Founded in 2008, Power Up is a leader in cell phone charging technology and innovative charging stations. The first to build and sell device-charging public kiosks in the U.S., Power Up has sold products in the U.S., Mexico, Africa and Canada. Located in Baltimore, Power Up manufactures its own products. Nominated “Entrepreneur of the Year” four years in a row, Power Up is the only charging company with proprietary smart charging technology. Learn more about charging innovations, products and how Power Up is currently helping cell phone users stay safe during viral outbreaks: www.PowerUpConnect.com.

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