Frequently Asked Questions

Why is Far-UV important?

Far-UV (222nm) is important because it is the only technology that is available today that can continuously and effectively disinfect air and surfaces safely with people present.  When configured in a line-of-sight fashion the photons produced by Far-UV lamps can deactivate and destroy airborne pathogens at the speed of light.  All other technologies provide either for a moment in time capability (think Clorox wipes) or are dependent on air exchange rates (think HVAC and upper room UVC solutions).  If you have a classroom full of kids and one of them sneezes, you don’t have the luxury of waiting for an air exchange to protect the other kids from the aerosolized viral particles.  Far-UV when configured properly, can provide that level of protection.


What types of organisms can Far-UV inactivate?

Far-UV actually “deactivates” pathogens, that is it destroys pathogens. This is much more compelling than UVC which only “inactivates” pathogens which can then be reconstituted through a process called photo reactivation.  Far-UV is known to be able to deactivate most human pathogens including viruses, mold, bacterium, fungus, prions, and protozoa.

What are the pros and cons of Far-UV?

The pros of Far-UV are that the lamps themselves can be made to have tremendously long life (up to 30K hours and more), they can be powered up to and greater than 2kw, they can be configured to produce very little ozone, and they are not environmentally hazardous.  In fact, Far-UV excimer lamps, when designed properly, can be recycled at a fraction of the original cost.  But most importantly, Far-UV technology is a powerful tool in the battle against pathogens and has virtually unlimited applications because the 222nm wavelength is safe for human exposure.  The cons of the technology include the limited production of the lamps, perceived high cost of the lamps, and the lack of regulatory oversight of the quality and efficacy of the lamps.

Are Far-UV Sterilray unfiltered lamps safe?

The issue surrounding filtering really boils down to the fact that not all excimer lamps are created equal.  Over the 25 years that we have been making lamps we have perfected the technique through the identification of 21 different factors that control lamp performance.  Such things as lamp life, lamp efficiency, ozone production, and spectral output are affected by the gas mixtures, the level of atmospheric pressure, and the use of a phased pulse power supply.  These are just a few of the controls that enter the equation.  The issue of filtering was necessary for Ushio and other excimer lamp producers because their lamp performance was such that they output secondary and tertiary emissions in such high output that their lamps were simply not safe for human exposure at the established ACGIH TLV levels for those additional wavelengths.  In other words, they created a marketing story that all excimer lamps need filters, when in fact that is not the case.

Far-UV Sterilray™ lamps are manufactured in such a way that a secondary output at 257 nm is less than 1/90th the output at 222.  The current TLV for 222 is approximately 479 mj/cm2 for skin exposure.  That is a time weighted value for eight hours of exposure.  The TLV for 4 hours is double that or 958 mj/cm2.  If we were to configure our lamps to hit the 479mj/cm2 TLV, our secondary output at 257nm would be at 479/90 or 5.3 mj/cm2, below the existing TLV for 257nm, which is 10 mj/cm2.  Even if we ran our lamps to the 222 TLV limit (which we don’t even get close), we would still be considered safe at other wavelengths because of the low emissions at those wavelengths.

What are the advantages of continuous 222nm FAR-UV disinfection over other methods?

222nm Far-UV: Safely & effectively sanitizes air and surfaces by destroying pathogens such as viruses, bacteria, mold and spores by delivering an appropriate dose of invisible disinfecting light.

Wipes and Chemical Solutions: Wiping down surfaces regularly can be a useful part of a multi-layered disinfection strategy but have not proven to be effective at eliminating the spread of pathogens like SARS-CoV-2 alone. The traditional sanitation practice of wiping down surfaces, spraying or fogging generates physical waste, introduces potentially troublesome chemicals to an environment and requires paid labor to implement. The cost of utilizing 222nm Far-UV disinfection lighting is often 50-100 times cheaper than those alternatives when factoring in labor and materials costs and is not subject to human error and missing intended spots. Attempting to clean while spaces are occupied is also disruptive and often impossible. In contrast, 222nm Far-UV lighting provides safe autonomous, and continuous disinfection while spaces are occupied, without the use of water, bleach, chemicals, rags, paper towels, mercury, hydrogen peroxide, cold plasma or ozone.

HEPA Filters: A HEPA (High-Efficiency Particulate Air) filter can be an important part of common air purifier systems and is recognized by NIOSH as an evidence-based disinfection solution. The potential challenge in relying on HEPA filters alone is that ASHRAE estimates only 40-60% of the air within a space is recirculated through the ductwork if the HEPA filter is mounted in the HVAC ductwork and even less may be filtered in smaller portable units. They also do nothing for surface contamination and could potentially spread the viral load beyond the area a contamination event would have naturally settled.

Deionization Systems: The potential attraction of deionization systems is they are cheap and their manufacturers indicate they may have relatively long product lives. However, as far as actual disinfection in real-world applications is concerned, there do not appear to be independent studies confirming evidence-based efficacy and there are reports they may be creating unwanted byproducts.

HVAC UV-C Disinfection: Ultraviolet light is the only evidence-based disinfection alternative recognized by ASHRAE to be effective. Appropriately sized 254nm UV-C systems in the ductwork can deactivate airborne pathogens in the ductwork fairly effectively. However, ASHRAE also estimates only 40-60% of the air within a space is recirculated through the ductwork where conventional UV-C can safely disinfect and be shielded from human exposure, leaving significant spaces where the viral load can remain within a room. Conventional 254nm UV-C in the ductwork also does nothing to treat the surfaces within a space leaving considerable additional exposure risk whereas 222nm Far-UV can treat all of the air and the tops of surfaces in a room.

Upper-Room Germicidal UV-C Disinfection: Upper Room Germicidal UV has proven to be even more effective at reducing the viral load in occupied rooms than HVAC ductwork based systems, particularly when utilized in a room with ceiling fans to provide better air mixing. Upper-Air germicidal UV-C (254nm) systems are designed not to expose people to their harmful radiation. However, when a carrier contaminates a space either with a sneeze, cough, talking, breathing or singing, gravity immediately begins to pull most of the pathogens towards the ground or other surfaces (such as desks, chairs, etc). As a result, while these upper air systems may also use air handling systems to try to fight gravity, they may not address a meaningful amount of the contaminated air and surfaces and may even keep some pathogens airborne longer which could be counterproductive. They also do not provide any surface treatment. Because 222nm Far-UV lighting is safe for human exposure, it can overcome these challenges from the ceiling to the floor in either upper-room or ceiling-mount fixtures, providing a much more comprehensive whole room disinfection solution.

Ultimately, 222nm Far-UV provides the safest, most cost-effective, evidence-based disinfection solution.

What are the best use-cases for Far-UV?

Best use cases of Far-UV are those instances where Far-UV can be used where other technologies cannot be used.  These include line of sight applications where people are present, agricultural applications where photo reactivation is a consideration, wound care, and skin disinfection where other wavelengths are not safe, and any disinfection application where the targeted pathogen is more susceptible to Far-UV than other technological interventions.


Why has Far-UV not come to market sooner?

Actually, Far-UV as produced by excimer lamps has been available in different product profiles for over fifteen years.  Unfortunately, it has taken a pandemic for the technology to get the recognition it deserves.  Even today, Far-UV has a PR problem because government agencies have not looked at Far-UV to help solve many of the world’s problems, including the pandemic.  Our opinion is that it will not get truly widespread adoption until Far-UV is part of the commercial building codes, much like fire suppression technology.


How can Far-UV help expedite the return to normalcy?

Far-UV can help expedite the return to normalcy by demonstrating the efficacy of the technology in the form of widespread adoption.  We would have thought two years ago that 222nm technology would have been the next Manhattan project.  However, the Federal government never took notice.


What should consumers look out for when purchasing Far-UV devices?

Because of the lack of regulatory oversight and yet developed industry standards there is a lot of carnival barking and marketing of inferior products that tend to confuse and distract potential adopters.  Those standards are coming in to place gradually through organizations such as the IUVA, IES, EPA, and ACGIH.  Other organizations and agencies such as ASHRAE, OSHA, and the FDA need to step up their game and help recognize that 222nm technology is extremely important in the protection of the human race.  Consumers need to be on the lookout for companies new to the Far-UV business and for cheap imported products that don’t perform as advertised.

Where are Sterilray Lamps made?

Sterilray lamps are manufactured in Somersworth, NH since 2008. All assembly of Sterilray products are done in New Hampshire by certifed contract manurfacturers.

Is Financial support available?

Yes! All Sterilray, Inc. products qualifies for ESSER (CARES Act, CRRSAA, ARPA) and other Federal funding that can pay for up to the entire cost of the equipment and installation. Other state and local funding is also often available to mitigate COVID-19 or otherwise improve public safety. Eligibility includes but is not limited to education, healthcare, transportation, infrastructure, various non-profits and restaurant applications. Sterilray, Inc. and its strategic partners can also provide financing solutions for Far-UV Sterilray products.

Ask Your Question

Call Us

(603) 516-2050

Order 222nm Products Today