Virus and Bacteria
What Wavelength Works For Virus and Bacteria….Two Different Things That Can Make You Sick
What Is UV Light?
We have been working in the visible light range from 405-470nm that kills a wide variety of bacteria including MRSA, Staph, Strep, Cdiff and more. See below (Visible Light). This is light that gets to earth and we have lights that focus on the 405-470nm range to kill bacteria.
We are now getting into the UV range. There are three different UV ranges. The one we need to be concerned with is UVC. This range is called “The Germicidal Range” because it is proven to kill Bacteria and Viruses.
LEDs and UVC: When you talk about UV and LED it is all about how you get the UVC light output. They do have LED Chips available in UVC nanometers (200-280nm). They also use a Quartz tube to get UVC output. The most effective germicidal wavelength occurs with a peak between 260 nm to 270 nm, the point at which DNA absorbs UV energy the most. Keep in mind these chips do not last 50,000 to 100,000 hours like the 5000K chips. UV is a different animal. But also keep in mind you don’t keep UVC lights on 14 hours a day. Maybe 5-15 minutes per session.
Does it kill Corona Virus? We don’t’ know exactly because this is a brand new virus and it has not been tested yet. Are UVC LEDs Effective Against COVID-19 (Coronavirus)?
Studies have confirmed that UVC light can be effective for combating SARS-COV (source). However, additional studies are needed to determine and confirm the specific dose response required to inactivate COVID-19 on different surfaces and materials.
Just read this….. Technology for Sterilization Applications to Prevent the Spread of Coronavirus
- Seoul’s violeds UV LED sterilization technology has been demonstrated to reduce influenza-type germs by 97%
- Just 60 seconds of UV-C (100 – 280nm) LED light exposure has been shown to sterilize 90% of coronavirus germs
- Automakers in China are actively exploring violeds UV LED technology for vehicle interior sterilization systems
- Seoul’s violeds UV LED sterilization technology has been deployed by the US National Aeronautics & Space Administration (NASA) aboard the International Space Station (ISS)
Ultraviolet light is electromagnet radiation with wavelengths shorter than visible light. UV can be separated into various ranges, with short ranges UV (UVC) considered (GERMICIDAL) Short wave ultraviolet radiation, in the “C” band (200-280nm) had been used for over 100 years.
What Is UVC? – Ultraviolet light is electromagnetic radiation with wavelengths shorter than visible light. UV can be separated into various ranges, with short range UV (UVC) considered “germicidal UV.” Short-wave ultraviolet radiation, in the “C” band (200 to 280 nanometers) has been used for over 100 years.
How Does UVC Work? – UV light in the form of germicidal lamps has been used since the late 1800s to kill the types of microorganisms that typically cause indoor air quality problems — bacteria, mold, yeast, and viruses.
At certain wavelengths UV is mutagenic to bacteria, viruses and other micro-organisms. At a wavelength of 2,537 Angstroms (254 nm) UV will break the molecular bonds within micro-organismal DNA, producing thymine dimers in their DNA thereby destroying them, rendering them harmless or prohibiting growth and reproduction. It is a process similar to the UV effect of longer wavelengths (UVB) on humans, such as sunburn or sun glare. Micro-organisms have less protection from UV and cannot survive prolonged exposure to it.
UVGI Systems – A UVGI system is designed to expose environments such as water tanks, sealed rooms and forced air systems to germicidal UV. Exposure comes from germicidal lamps that emit germicidal UV electromagnetic radiation at the correct wavelength, thus irradiating the environment. The forced flow of air or water through this environment ensures the exposure.
Finsen Lamps – Niels Ryberg Finsen (1860-1904) is first to employ UV rays in treating disease. He is awarded the Nobel Prize for Medicine in 1903. He invents the Finsen curative lamp, which was used successfully through the 1950s. UVC is used to disinfect the municipal water supply in Marseille, France, in 1908.
In the 1930’s, Westinghouse Electric Company R&D engineers and scientists developed and patented the first commercially available ultraviolet lamps. They are used primarily in hospitals.
The first products were simple compared to modern-day technology, but they were very effective and initially were sold in conjunction with water filters to the U.S. Department of Agriculture to disinfect surface drinking water sources used by Arizona agricultural workers.
Broad Market Acceptance of UVC – After World War II, UVC is used for sterilizing air in hospitals, kitchens, meat storage and processing plants, bakeries, breweries, dairies, beverage production, pharmaceutical plants, and animal labs — anywhere microbiological contamination is a concern. Typically a beam of UVC is directed across the ceiling of a room. During the 1950s UVC is incorporated into air handling equipment. It becomes a major component in the control and eradication of tuberculosis (TB).
Move Away From UVC – During the 1960s, concern about microbes lessens with the introduction and increasing availability of new drugs and sterilizing cleaners. As mechanical ventilation becomes more popular, UVC performance suffers due to the lack of effective UVC performance in cold-air settings.
Technological Improvements – In the 1970’s and 80’s, concerns over chemical use and improvements in UVC bulb manufacturing caused more organizations and companies to revisit UVGI. In the early 1990’s, UVGI was pioneered into significant water treatment processing for municipal systems as well as for treatment of swimming pools.
The introduction of UVC into HVAC systems is pioneered in 1996. Recent technological advancements have made it possible for companies to produce high-output ultraviolet germicidal devices further improving efficiency and effectiveness.
Why UV-C Cannot Produce Ozone
The Ultraviolet Germicidal Irradiation (UV-C) wavelength is an invaluable tool for an HVACR system. By leveraging germicidal energy to keep refrigeration coils free of microbial growth, facility managers also enjoy the benefit of reducing the spread of airborne infectious agents.
However, some facility managers may hesitate to leverage these benefits for their application due to a concern about ozone. While the Ultraviolet spectrum contains four separate wavelengths—UV-A, B, C and Vacuum UV—each operates at different energy levels and only one is capable of producing ozone (Vacuum UV).
As you’ll note in the graphic below, Vacuum UV operates in the 100-200nm range, where it is capable of producing ozone. UV-C, conversely, reaches its optimal germicidal strength near 253.7nm. Because ozone may only be produced below 200nm, at 253.7nm (rounded to 254nm), the germicidal wavelength does not generate ozone.
In addition to the stronger 254nm wavelength that does not produce ozone, UV-C lamps offer another layer of ozone protection.
Most germicidal lamps, including those from UV Resources, are produced with doped quartz glass, which blocks the transmission of the 185nm ozone-producing wavelength. The doped quartz glass allows the 253.7nm radiation to pass through, but it blocks the 185nm wavelength from escaping. Therefore, germicidal lamps with doped glass CANNOT produce ozone.
WHAT IS OZONE?
Ozone is present in low concentrations throughout the earth’s atmosphere. Some researchers say that this chemical is “good up high, but bad down low.” Without the ozone layer protecting our Earth’s stratosphere, for example, the Sun’s ultraviolet radiation would make life on Earth uninhabitable. At street level, however, a high concentration of ozone is toxic to plants and animals. In humans, ozone can irritate nasal passages, cause nausea and extended exposure can lead to lung inflammation.
Ozone, also called Vacuum Ultraviolet (UV-V), is a gas molecule that contains three (3) oxygen atoms – and as such, it has a destabilizing effect on oxygen in the air (leading to its irritation and danger to humans). A UV lamp “tuned” to 185nm can create ozone from oxygen (O2) by disrupting the O2 molecule and splitting it into two oxygen atoms. These two oxygen atoms attempt to attach to other oxygen molecule (O2). It is the attachment of this third oxygen atom that creates ozone (O3).
Ironically, UV light in the 240-315nm wavelength will break this third oxygen atom attachment above and convert it back to oxygen. The peak ozone destruction occurs at the 254nm wavelength. So, a UV-C lamp at the 253.7nm wavelength will actually destroy ozone!