Electromagnetic energy travels in waves and spans a broad spectrum from very long radio waves (AM/FM radio, Wifi, etc.) to very short gamma rays (nuclear power). Ultraviolet (UV) light is a portion of the electromagnetic spectrum that falls in the range between visible light and X-rays. This form of non-ionizing radiation is emitted by the sun.
Because UV light has a shorter wavelength and higher frequency than our brain can perceive, it is not visible to the human eye. The electromagnetic spectrum of UV radiation is further subdivided into the following ranges.
The UV-C portion of the electromagnetic spectrum ranging 200-300 nm, and peaking at about 260 nm, is strongly absorbed by pyrimidine bases found in DNA and RNA, the two most important molecules used to encode the genetic information needed for organisms to develop and survive. The direct absorption of UV-C by DNA and RNA leads to the formation of dimers between two adjacent pyrimidines in a strand, resulting in the disruption of the DNA/RNA chain, malfunction of the microorganism’s replication mechanism, and their effective inactivation.
Proteins also absorb UV light and can be damaged. When high doses of UV-C are applied to microorganisms within line of sight, DNA damage occurs beyond repair. For this reason, UV-C light is known as germicidal. Germicidal UV-C is an effective and proven disinfection method that been used for decades for air and water treatment.
COVID-19 revealed how susceptible we are to biosecurity threats and has reinforced the importance of taking preventive measures to avoid personal illness, mass disruption and financial crisis. Glissner helps break the chain of infection.
Many diseases spread through contact with fomites. When an infected person sneezes or coughs, they send infectious droplets into the air that land on objects that then become fomites for disease spread. Smartphone are a very common fomite for disease spread. If a healthy individual touches one of these contaminated fomites, and then touches their eyes, nose or mouth, they can become ill. With the continued rise of mobile technology development and adoption, smartphone ownership is growing exponentially across the globe. There are approximately 6.3 billion smartphone users worldwide; these phones are covered in germs (precisely 25,127 per sq inch!), some of which can survive on surfaces for hours and even days.
In some instances, a new virus can be completely harmless, while in others it can lead to devastating local outbreaks and a global pandemic. In a technology-driven society, this means that personal hygiene is evolving to keep up with this challenge in a rapidly changing world. Hand hygiene extends beyond hand-washing to everything we touch in our daily lives, including smartphones which have become our “third hand”. Since most objects we touch can’t be washed or exposed to chemical disinfectants, there has been renewed interest in chemical and liquid-free solutions such as germicidal UV-C light for sanitization of high-touch items and surfaces.
Controlled tests conducted in microbiology laboratories to calculate the kill rate for various pathogens are used to determine the efficacy of smartphone UV-C sanitizers. When controlled tests are performed by experienced microbiologists using industry-leading standards, the device efficacy against pathogens can be considered a reflection of its real-world use. Buyers should look for evidence that the testing was conducted in a GLP-compliant, Environmental Protection Agency (EPA)-inspected laboratory, and a testing report is available for review. ASTM International is the international standards organization that developed the consensus technical standard for antimicrobial efficacy of UV-C devices, Standard Practice for Determining Antimicrobial Efficacy of Ultraviolet Germicidal Irradiation Against Microorganisms on Carriers with Simulated Soil, also known as ASTM E3135-18. The standard describes the protocol laboratories must adhere when conducting the test. This includes parameters such as the test surface, drying conditions and soiling agents to simulate the presence of bioburden on the tested surface.
Log Reduction, as it relates to disinfection or cell inactivation, is a mathematical term that conveys how effective a something is at inactivating pathogens (in our case a UV-C device). In microbiology, log reductions are often used to calculate changes in microorganism numbers. Because microorganisms grow exponentially, calculating the magnitude of change in their numbers is easier using a logarithmic scale (log scale).
In simple terms, an increment of 1 corresponds to a reduction of colony forming units (CFU) are an estimation of the number of viable microorganisms in a sample) by a factor of 10. For example, if the number of CFUs in the control was found to be 1,000,000, and the number of CFUs after using the UV-C device was only 10, that would be a Log reduction of 5 or a reduction of 99.999% of microorganisms. The greater the log reduction the more effective the device is at inactivating microorganisms.