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.
