Frequently Asked Questions
1. What is UV light?
UV or Ultraviolet is a form of electromagnetic radiation with a wavelength ranging from 100 nanometres to 400 nanometres(nm). Electromagnetic radiation comes from the sun and is transmitted in waves or particles at different wavelengths and frequencies. This wide range of wavelengths is known as the electromagnetic (EM) spectrum and is generally divided into seven regions in order of decreasing wavelength and increasing energy and frequency such as radio waves, microwaves, infrared (IR), visible light, ultraviolet (UV), X-rays, and gamma-rays.
As you can see Ultraviolet light falls in the range of the EM spectrum between visible light and X-rays. UV radiation present in sunlight constitutes about 10% of the total electromagnetic radiation output from the Sun.
UV is generally divided into three sub-bands:
- UVA, or near UV (315 – 400 nm)
- UVB, or middle UV (280 – 315 nm)
- UVC, or far UV (180 – 280 nm)
2. What are the beneficial uses of germicidal UV light?
Germicidal Ultraviolet or UVC light causes damage to the nucleic acid of microorganisms and deactivates the DNA of bacteria, virus, and other pathogens by forming covalent bonds between certain adjacent bases in the DNA. It thus destroys their ability to multiply a key factor in the spread of infections.
- Ultraviolet is a chemical-free and cost-effective approach to disinfection.
- Germicidal lights eliminate bacteria, mould, fungi, and other germs found in the air that are invisible to the naked eye
- They sanitise surfaces and eliminate pollutants, disinfecting the air to protect your family from allergies and respiratory infections.
3. How does UVC disinfect?
Unlike other disinfection methods, UV light disinfection offers eco-friendly and effective solutions to inactivate microorganisms in a hassle-free approach. The bacterias, protozoa, and viruses, when exposed to the UV light weaken and are incapacitated to further reproduction and spread of infections.
UVC light has demonstrated efficiency against pathogenic organisms, including the virus responsible for typhoid, cholera, hepatitis, and other viral diseases. The high energy associated with the UV light due to its short wavelength (254 nanometres), when absorbed by the RNA and DNA of the microorganisms damages their nucleic acids and inactivates them.
This absorption of UV energy between adjacent nucleotides results in the formation of new bonds, creating double bonds or dimers. This double bond of adjacent molecules also called dimerisation, particularly thymine, is common photochemical damage. The continuous exposure to UV light forms numerous thymine dimers in the DNA of bacteria and viruses preventing replication and causing an inability to infect.
4. What pathogens can be killed by UVC light?
UVC light is highly effective in inactivating pathogens like bacteria, viruses, and other microorganisms. Due to its high energy, it destroys the molecular bonds that hold together the DNA of viruses and bacteria, including “superbugs,” which have developed a stronger resistance to antibiotics.
There are UV devices available that can produce strong enough UVC light in circulating air or water systems to make them inhospitable environments to microorganisms such as bacteria, viruses, moulds, and other pathogens leaving them unable to perform vital cellular functions.
Research conducted by Cornell University has confirmed the effectiveness of UVC light on COVID-19 coronavirus and published its findings.
However in order to be effective against any pathogen a very high intensity of ultraviolet light is required. Most UVC LEDs currently available in the market DO NOT give out high levels of radiation needed to inactivate these pathogens there by requiring much longer time to achieve the inactivation. The actual time needed to kill the different pathogens can be found in the Dosage Chart*.
The best, most effective and proven UVC sources are the low-mercury discharge lamps being used by VIOlight.
6. UVC dosage - Ultraviolet sterilisation dosage for various microorganisms
The average bacterium will be killed in 10-20 secs at a distance of six inches from a UV lamp.
7. Is UVC safe for humans?
In human beings, skin exposure to germicidal wavelengths of UV light can cause rapid sunburn and skin cancer. Exposure of the eyes to the UV radiation can produce extremely painful inflammation of the cornea and temporary or permanent vision impairment, up to and including blindness in some cases. UV can also damage the retina of the eye. EXTREME CAUTION is advised when handling UVC devices and all VIOlight products come with necessary safety and operating instructions.
8. What is the wavelength & frequency of UV?
Ultraviolet light falls in the range of the EM spectrum between visible light and X-rays and has frequencies of about 8 × 1014 to 3 × 1016 cycles per second, or hertz (Hz), and wavelengths of about 380 nanometers (1.5 × 10−5 inches) to about 100 nm (4 × 10−7 inches). UV has a wavelength shorter than visible light and longer than the x-rays. UV wavelength is between 400 nanometres and 100 nanometres.
9. Do I need to wear gloves when replacing UVC lamps?
Do not touch the glass portion of the germicidal UV lamp with bare hands. Use cotton, latex, nitrile or tightly woven fabric gloves before replacing the UVC lamp.
10. How often do I need to replace my UVC lamps?
Even though a UV lamp may produce visible light past the 10,000 hours, the ultraviolet output decreases over time. You can replace your UV lamp every 9,000 hours or approximately every 12 months. An annual replacement schedule is also recommended for those suffering from allergies and other respiratory conditions.
11. Does UVC damage surrounding materials?
For example, long-term exposure of germicidal UVC light to plastics will degrade plastics and reduce its useful life.
12. Does UVC damage eyes and skin?
13. Do I have to wear PPE when using UVC?
14. Is UVC visible?
15. Can UVC light disinfect unopened mail?
16. Can UVC light be used to disinfect keyboards, phones, keys, and computer mice?
17. What are the limitations to the use of UVC light for surface disinfection?
So the design of the UVC system plays a very important role in ensuring that disinfection is complete & thorough. It’s important to note microorganisms in water and air are susceptible to UV radiation.
18. How long do the effects of UVC disinfection last?
19. How often should you disinfect your space with UVC light?
20. What distance and how long do I need to expose an article to UVC light to sanitise it?
In general the closer the article is to the UVC source the more intensity of UVC dodge it receives. The more time it’s exposed to the UVC source the more dosage it receives.
21. Important definitions
Dose: the measure of quantum of UV energy that is delivered to microbes. It is the product of intensity of the light times the length of exposure. Different types of organisms require a different dose of UV to be inactivated or killed.
Electromagnetic spectrum: The entire spectrum, considered as a continuum, including microwaves, infrared light, ultraviolet light, X-rays, gamma rays, and visible light
Inactivation: To stop the activity of certain biological substances which is critical to stopping its reproductive cycle and ability to spread.
Intensity: The amount of UV energy produced, measured in milliwatts per square centimeter.
Spectrum: A band of radiation produced by separation of the components of light by their different degrees of refraction according to wavelength. The ultraviolet spectrum of light consists of wavelengths from 100-400 nm.
Pathogen: Any germ or microbe that can cause infections in humans and animals, including viruses, bacteria, and fungi.
Wavelength: The distance between successive crests of a wave, especially points in an electromagnetic wave. Visible light corresponds to a wavelength range of 400-700 nanometers (nm).
UVA Light: UV spectrum from 320-400 nm. Black lights emit UV-A light.
UVB Light: UV spectrum from 280-320 nm and is most commonly associated with sunburn or freckling, but also produces some germicidal effects.
UVC Light: UV spectrum from 200-280 nm known for its germicidal effects