We get it. The idea that a simple purple light can protect you from germs sounds... dodgy.
What is UV light?
Let's start with the basics. The world around you is filled with waves of energy from the Electromagnetic Spectrum. Many of these waves you will have heard of; radio waves, micro waves, infrared, X-Rays, Gamma Rays and ultraviolet. Visible light, the stuff which is enabling you to read this text, is also part of the same Spectrum.
Ultraviolet (UV) light refers to waves which are between 100 and 400 nanometres in length. No idea what that means? A hair on your head is about 90,000 nanometres wide! UV can itself be subdivided into 3 different types:
- UV-A (315-400nm): the longest UV waves, the type of UV found in an old school blacklight, and in 95% of the Sun's UV radiation which reaches the Earth's surface
- UV-B (280 - 315nm): medium length waves which are the main cause of sun burn and skin cancer. Without sunscreen, UV-B rays will burn your skin in as little as 15 minutes
- UV-C (100 - 280nm): the shortest UV waves, none of which gets through Earth's atmosphere from the Sun. Proven to kill germs though.
How does it kill germs?
Most of the ways we try to kill germs rely on some form of chemical, whether that's antibiotic tablets, disinfectant spray, or alcohol hand sanitiser. All of these methods work in different ways, but with one principle goal - to damage and/or destroy the exterior of germ cells so that everything leaks out and the cell dies.
UV light does the opposite. UV-C waves are so small that they pass right through the exterior of cells, and in fact pass right through the whole germ. Along the way though, some waves will crash into the DNA at the heart of the germ - the part which control's the germs behaviour and its very ability to live. The UV-C waves break apart some of the chemical bonds which hold DNA together (imagine that lovely double helix model in your school science lab having every 3rd joint broken apart). With the DNA broken, the germ is dead and can't make you sick.
Don't want to take our word for it?
Fair enough, we've only just met. Why should you believe our little science lesson?! Hopefully the links below will demonstrate just how comprehensively accepted the science behind germicidal UV really is...
- "How does ultraviolet light kill cells?", Scientific American
- "Far UV-C light: A new tool to control the spread of airbourne microbial diseases", Nature Magazine
- "Germicidal Efficacy & Mammalian Skin Safety of UV Light", US National Library of Medicine
- "UV light system adds to tough infection control regime", The Walton Centre NHS Foundation Trust
- "The effects of ultraviolet radiation on anti-biotic resitant bacteria", Europe Published Medical Community
- "Using the power of light: preventing the airborne spread of Coronavirus and Influenza virus", Columbia University Centre for Radiological Research