222 nm UV Light: Far UVC Effectiveness and Safety

Ultraviolet light in the UVC range is proven to have germicidal properties, with 222 nm UV light showing high efficacy and safety. Standard UVC germicidal lamps emit wavelengths at 254 nm, proven to have high germicidal effectiveness by breaking the DNA bonds inside the nucleus of harmful microbes and pathogens. 254 nm UV lamps, however, are not safe to use when humans are present and pose risks to damaging skin and eyes.

222 UV lamps are showing the same germicidal properties and are much safer than 254 nm lamps due to the way 222 nm wavelengths are absorbed by the protein layer of cells. 222 nm UV light is also known as Far UVC and is considered safe to use around humans without risk of human exposure to skin or eyes.

222 nm UV Light Effectiveness

Both 222 nm and 254 nm UV lamps emit UVC wavelengths that inactivate viruses and bacteria. 222 nm UV light penetrates the microbe’s cell nucleus and breaks the DNA bond to prevent replication, thus rendering the cell harmless, the same as 254 nm UV lamps. 222 nm UV lamps go even further than inactivating the cell, however, and actually destroy pathogens.

When standard UVC lamps inactivate pathogens, there is a possibility that they could be reconstituted through a process called photoreactivation. This is not possible with 222 nm UV light which is known to deactivate and destroy most harmful human pathogens, including bacterium, viruses, fungus, mold, protozoa, and prions. Far UVC light has been the focus of many studies for over a decade, with many research studies showing high efficacy against a wide range of known harmful pathogens, including alpha and beta coronaviruses, influenza (H1N1), and adenovirus.

222 nm, Far UVC light is shown to safely and effectively inactivate human airborne coronaviruses, with research showing effectiveness at killing the SARS-CoV-2 virus that causes COVID 19. The study showed that even low doses of far UVC light inactivated 99.9% of aerosolized coronavirus. Much research has been conducted on the effectiveness of standard germicidal lamps for SARS-CoV-2, showing that UV light does kill COVID in air and on surfaces.

Far UVC lamps designed to emit 222 nm are also called Excimer lamps and are in use today in many applications, providing UVC germicidal protection with significantly safer operation.

222 nm UV Lamps: Excimer Lamp Effectiveness

Excimer lamps that emit 222 nm UV light are produced by creating a high-voltage discharge in a glass tube lamp with the proper mixture of gases to create 222 nm when energized. The intensity of the output can vary depending on the input power, and an optical filter can be included to ensure that harmful wavelengths above 230 nm are removed. 222 nm Excimer lamps are showing high effectiveness at killing viruses on surfaces, in the air, and safely inactivating airborne human coronaviruses.

Safety of 222 nm Far UVC Light

222 nm Far UVC light is highly effective at destroying harmful pathogens and is opening the door for many uses beyond traditional germicidal lamps due to the ability to operate safely in the presence of humans. 254 nm light used in standard germicidal lamps is absorbed by DNA to kill harmful cells but is not easily absorbed by proteins, which means it can penetrate deeper into human skin and damage the DNA of actively dividing skin cells which can lead to cancer.

222 nm UV light, however, is also highly absorbed by DNA but is also absorbed by proteins, which are contained in the outer membrane shell of all viruses and bacteria. This increases the effectiveness of 222 nm light against some microbes while also making it much safer for use around humans. Since 222 nm light is absorbed by proteins, it will not fully penetrate into the thick protein-rich layer of human cells.

The outer layer of human skin consists of dead skin cells with no active cells and provides an armored layer against 222 nm light. A similar layer of cells protects the eyes. Since 222 nm UV light never reaches the DNA of actively dividing cells, it is safer for use and human exposure.

Harnessing the Power of UVC Disinfection to Combat Germs

In the wake of the COVID-19 pandemic, the importance of proper disinfection practices has become more apparent than ever. While traditional cleaning methods play a vital role in eliminating pathogens, the development of innovative technologies has led to the rise of UVC disinfection. UVC, or ultraviolet-C, radiation has proven to be a potent germicidal agent, offering an efficient and chemical-free solution to combat harmful microorganisms.

Understanding UVC Disinfection

UVC radiation is a form of ultraviolet light with wavelengths ranging from 200 to 280 nanometers (nm), with 254 nm being one of the most effective wavelengths for UV C disinfection. Unlike UVA and UVB rays, which can penetrate the Earth’s atmosphere and are responsible for the common sunburn, UVC is completely absorbed by the ozone layer. UV C lamps replicate the proper wavelength required for UVC radiation to eliminate germs in many applications.

Germicidal UVC lamps are safe for use in controlled environments with the proper safety measure in place, as they can pose a risk to human eyes and skin. When exposed to UVC radiation, microorganisms such as bacteria, viruses, and fungi are rendered inactive by damaging their DNA and disrupting their cellular functions. This process effectively prevents their replication and spread.

Effectiveness of UVC Disinfection

UVC disinfection has gained popularity due to its high efficacy in eliminating a wide range of pathogens. Numerous studies have demonstrated its effectiveness against various viruses, including SARS-CoV-2, the virus responsible for COVID-19. UVC radiation can be deployed in various settings, such as hospitals, laboratories, offices, restaurants, and public spaces. UVC radiation is effective for use in surface disinfection, air purification, and water sterilization.

In recent years, research has also focused on the benefits of far-UVC radiation. Far-UVC emits a shorter wavelength (around 222 nanometers) and is less harmful to human skin and eyes compared to conventional UVC radiation. This opens up possibilities for continuous disinfection in occupied spaces, offering a safer and more sustainable solution for public areas.

UVC Lamp Safety Considerations

While UVC radiation is highly effective in disinfection, precautions must be taken to ensure the safety of human exposure. Direct exposure to UVC radiation can cause skin burns and eye injuries, similar to sunburn and UV overexposure. Therefore, it is crucial to employ UVC disinfection systems that are properly designed, shielded, and used in controlled environments to minimize the risk of harm. This includes the use of protective gear and ensuring that humans are not present during the disinfection process.

UV C Disinfection Lamp Types

To harness the power of UV disinfection, specialized UV C lamps are used that emit the required wavelengths for germicidal effectiveness. LightSources, a leading manufacturer of UV lamps, offers a comprehensive range of UVC germicidal lampsand far-UVC lamps for various applications.

Germicidal lamps are designed to emit UVC radiation at a peak wavelength of 254 nanometers, which is highly effective in eliminating pathogens. These lamps are commonly used in air and water purification systems, surface disinfection devices, and HVAC units.

Far-UVC lamps, on the other hand, emit shorter wavelengths, around 222 nanometers. LightSources’ far-UVC lamps are engineered to deliver optimal germicidal effects while minimizing the risk to human health. These lamps are ideal for continuous disinfection in occupied spaces, providing an added layer of safety and protection.

UVC disinfection has emerged as a powerful and chemical-free method to combat the spread of harmful microorganisms. Its efficacy in eliminating viruses and bacteria, including the notorious SARS-CoV-2, has made it an essential tool in the fight against infectious diseases. However, it is crucial to implement UV germicidal lamps and disinfection systems safely and responsibly, adhering to recommended guidelines to protect human health.

Excimer Lamps: Many Uses Beyond Far UVC

Excimer lamps are ultraviolet lamps that are designed to emit UV wavelengths in the range of approximately 170 nanometers (nm) to 230 nm, dependent upon noble gas excimers present. Excimer lamps are useful in many applications, such as UVC sterilization, ozone generation, and UV curing processes.

What is an Excimer Lamp?

Excimer is a term that refers to a temporary atomic state where high-energy atoms create short-lived molecular pairs, or dimers, when electronically excited.

Excimer refers to a transient atomic state in which electronically excited high-energy atoms create short-lived molecular partners or dimers. UVC photons are released as excited dimers, excimers, return to their original state. The term excimer refers specifically to homodimeric bonds, a bond between the same species of molecules such as xenon (Xe). A xenon excimer lamp uses Xe atoms to form excited Xe2 dimers, which result in UV photons emitted at the 172 nm wavelength.

Heterodimeric bonds (bonds from two different structural species), has the official term of an exciplex. An example of an exciplex is the bond with Krypton-chloride (KrCl), which is an exciplex that emits wavelengths in the range of 222 nm. 222 nm UV light is recognized for high antimicrobial capabilities and is also referred to as Far UVC.

Excimer lamps are the generally accepted term for lamps that emit both excimer and exciplex radiation in the range of 172 nm and 222 nm, respectively.

How Do Excimer Lamps Work?

Excimer lamps irradiate the desired UV wavelength in the vacuum ultraviolet (VUV) range (between 100 – 200 nm) in a specialty coated, sealed quartz glass chamber with noble gases. An intense plasma discharge also called a dielectric barrier discharge, is generated from the high-energy electrons. The atomic excitement of noble gases is induced by the plasma, which triggers the creation of excited dimers, or excimers. The Excimer-specific UV radiation results during the final emission stage when Excimer molecules disassociate and return to their original state, all of this occurring in nanoseconds.

Excimer Lamp Application Uses

Excimer lamps are ideal in many applications and are gaining significant attention with the ability to disinfect surfaces with the same efficacy as traditional 254 nm UV lamps without the risk of human exposure.

Excimer Lamps for Sterilization, 222 nm

Excimer lamps designed to emit 222 nm radiation, also called Far UVC lamps, are increasing in use for sterilization applications worldwide with the same germicidal effectiveness as traditional 254 nm lamps and can be used in the presence of humans. In one study published at the National Library of Medicine, the effects of 222 nm UVC light for disinfection and healing effects were shown to be effective on methicillin-resistant Staphylococcus aureus infection in mouse wounds without damaging DNA.

Both 222 nm lamps and 254 conventional low-pressure mercury lamps were used in this study. 222 nm UVC light significantly reduced bacterial count on mice skin wounds infected with methicillin-resistant Staphylococcus aureus (MRSA). When compared with the effectiveness on days 3, 5, 8, and 12, irradiation of bacterial counts with 222 nm UV light was the same as or even more effective than 254 nm radiation.

Sterilization and Safety

While 254 nm UVC germicidal lamps have been used for decades and are highly effective at eliminating the risk of infection from many viruses, bacteria, and harmful pathogens, exposure to this wavelength is harmful to humans. 254 nm UV radiation causes DNA lesions such as cyclobutane pyrimidine dimers (CPD) in human cells. Long-term repeated exposure can cause skin cancer and eye damage.

Short wave, 222 nm UV light, is absorbed by the proteins in the membrane and therefore does not reach the nucleus of human cells. This same study evaluated the safety of 222 nm excimer lamps vs 254 nm conventional germicidal lamps and found that immediately after irradiation, the epidermis irradiated with 254 nm light showed the presence of CPD expressing cells but was not present after irradiation with 222 nm UVC. Excimer lamps emitting 222 nm light are proving to provide highly effective sterilization combined with human biological safety.

Excimer lamps have other uses in addition to sterilization, and not all Excimer lamps are far UVC lamps.

Excimer Lamps for Surface Activation, 172 nm

Alteration of surface energy is required in many industrial applications for surface treatments, such as applying coatings and adhesives to substrates. 172 nm lamps are an excellent choice for surface modification and provide additional benefits of cleaning and activating substrate surfaces simultaneously. 172 nm provides powerful electromagnetic energy to directly crack major bonds in organic molecules without altering any physical surface properties.

Excimer lamps designed to emit 172 nm increase the wettability and surface energy of various substrates such as glass, metals, and polymers. Surface energy is measured in millinewtons per metre (mN/m), with 172 nm excimer lamps meeting surface activation energy requirements for solvent inks, UV inks, water-based systems, and coatings. Excimer lamp technology provides many benefits to UV curing applications, including cleaning, bonding, and coating.

Surface Activation Alternative Treatment

172 nm Excimer lamps are a good alternative to plasma and Corona-based surface treatments with considerably less excess heat and reduced thermal load. Both plasma and Corona are electrical discharge surface activation methods. Excimer lamps
provide effective surface activation without damage to surface structure, resulting in better results for bonding.

Ozone Production with Excimer Lamps, 185 Nm

Excimer lamps are also effective at producing ozone, a natural oxidizer, odor reducer, and disinfectant effective in air and water sterilization applications. Ozone is typically produced at 185 nm standard low-pressure mercury lamps, although Excimer lamps filled with xenon are an efficient source to generate ozone with no nitrogen oxides (NOx) as the UV radiation is not high enough to excite nitrogen in the air.

Excimer lamps are proving to be a very exciting development and an increasingly promising offering in the UV lamp market.

LightSources is currently in the development of Excimer lamps, and we offer a wide selection of UVC germicidal lamps used in surface, water, and air sterilization systems worldwide. We design, engineer, and manufacture UVC germicidal lamps, UV curing lamps for surface treatment applications, as well as ozone-producing lamps.

What is an Excimer Lamp?

Excimer is a term that refers to a temporary atomic state where high-energy atoms create short-lived molecular pairs, or dimers, when electronically excited.

Excimer refers to a transient atomic state in which electronically excited high-energy atoms create short-lived molecular partners or dimers. UVC photons are released as excited dimers, excimers, return to their original state. The term excimer refers specifically to homodimeric bonds, a bond between the same species of molecules such as xenon (Xe). A xenon excimer lamp uses Xe atoms to form excited Xe2 dimers, which result in UV photons emitted at the 172 nm wavelength.

Heterodimeric bonds (bonds from two different structural species), has the official term of an exciplex. An example of an exciplex is the bond with Krypton-chloride (KrCl), which is an exciplex that emits wavelengths in the range of 222 nm. 222 nm UV light is recognized for high antimicrobial capabilities and is also referred to as Far UVC.

Excimer lamps are the generally accepted term for lamps that emit both excimer and exciplex radiation in the range of 172 nm and 222 nm, respectively.

How Do Excimer Lamps Work?

Excimer lamps irradiate the desired UV wavelength in the vacuum ultraviolet (VUV) range (between 100 – 200 nm) in a specialty coated, sealed quartz glass chamber with noble gases. An intense plasma discharge also called a dielectric barrier discharge, is generated from the high-energy electrons. The atomic excitement of noble gases is induced by the plasma, which triggers the creation of excited dimers, or excimers. The Excimer-specific UV radiation results during the final emission stage when Excimer molecules disassociate and return to their original state, all of this occurring in nanoseconds.

Excimer Lamp Application Uses

Excimer lamps are ideal in many applications and are gaining significant attention with the ability to disinfect surfaces with the same efficacy as traditional 254 nm UV lamps without the risk of human exposure.

Excimer Lamps for Sterilization, 222 nm

Excimer lamps designed to emit 222 nm radiation, also called Far UVC lamps, are increasing in use for sterilization applications worldwide with the same germicidal effectiveness as traditional 254 nm lamps and can be used in the presence of humans. In one study published at the National Library of Medicine, the effects of 222 nm UVC light for disinfection and healing effects were shown to be effective on methicillin-resistant Staphylococcus aureus infection in mouse wounds without damaging DNA.

Both 222 nm lamps and 254 conventional low-pressure mercury lamps were used in this study. 222 nm UVC light significantly reduced bacterial count on mice skin wounds infected with methicillin-resistant Staphylococcus aureus (MRSA). When compared with the effectiveness on days 3, 5, 8, and 12, irradiation of bacterial counts with 222 nm UV light was the same as or even more effective than 254 nm radiation.

Sterilization and Safety

While 254 nm UVC germicidal lamps have been used for decades and are highly effective at eliminating the risk of infection from many viruses, bacteria, and harmful pathogens, exposure to this wavelength is harmful to humans. 254 nm UV radiation causes DNA lesions such as cyclobutane pyrimidine dimers (CPD) in human cells. Long-term repeated exposure can cause skin cancer and eye damage.

Short wave, 222 nm UV light, is absorbed by the proteins in the membrane and therefore does not reach the nucleus of human cells. This same study evaluated the safety of 222 nm excimer lamps vs 254 nm conventional germicidal lamps and found that immediately after irradiation, the epidermis irradiated with 254 nm light showed the presence of CPD expressing cells but was not present after irradiation with 222 nm UVC. Excimer lamps emitting 222 nm light are proving to provide highly effective sterilization combined with human biological safety.

Excimer lamps have other uses in addition to sterilization, and not all Excimer lamps are far UVC lamps.

Excimer Lamps for Surface Activation, 172 nm

Alteration of surface energy is required in many industrial applications for surface treatments, such as applying coatings and adhesives to substrates. 172 nm lamps are an excellent choice for surface modification and provide additional benefits of cleaning and activating substrate surfaces simultaneously. 172 nm provides powerful electromagnetic energy to directly crack major bonds in organic molecules without altering any physical surface properties.

Excimer lamps designed to emit 172 nm increase the wettability and surface energy of various substrates such as glass, metals, and polymers. Surface energy is measured in millinewtons per metre (mN/m), with 172 nm excimer lamps meeting surface activation energy requirements for solvent inks, UV inks, water-based systems, and coatings. Excimer lamp technology provides many benefits to UV curing applications, including cleaning, bonding, and coating.

Surface Activation Alternative Treatment

172 nm Excimer lamps are a good alternative to plasma and Corona-based surface treatments with considerably less excess heat and reduced thermal load. Both plasma and Corona are electrical discharge surface activation methods. Excimer lamps
provide effective surface activation without damage to surface structure, resulting in better results for bonding.

Ozone Production with Excimer Lamps, 185 Nm

Excimer lamps are also effective at producing ozone, a natural oxidizer, odor reducer, and disinfectant effective in air and water sterilization applications. Ozone is typically produced at 185 nm standard low-pressure mercury lamps, although Excimer lamps filled with xenon are an efficient source to generate ozone with no nitrogen oxides (NOx) as the UV radiation is not high enough to excite nitrogen in the air.

Excimer lamps are proving to be a very exciting development and an increasingly promising offering in the UV lamp market.

LightSources is currently in the development of Excimer lamps, and we offer a wide selection of UVC germicidal lamps used in surface, water, and air sterilization systems worldwide. We design, engineer, and manufacture UVC germicidal lamps, UV curing lamps for surface treatment applications, as well as ozone-producing lamps.