UV rays are known to the general public for two things: the sun's rays and ultraviolet tanning booths.
However, several types of ultraviolet exist, each with its own characteristics. What's the difference between UV, UV-A, UV-B and UV-C?
WHAT ARE UV RAYS?
The sun naturally emits several types of UV rays, more or less dangerous for the skin. Our ozone layer, which protects our planet, filters out these rays and makes life possible.
Nevertheless, thanks to technological advances, we've managed to reproduce them artificially in tanning booths, water disinfection equipment and, more recently, in air and surface disinfection machines.
Light is measured in nanometers (billionths of a meter). It is these nanometers that define whether light is visible or not. If the wavelength is between 700 and 400 nm, this is what we call "visible light", the kind we see every day, ranging from an intense red to a very dark violet. Below this is ultraviolet light, where we find other types of UV, invisible to the naked eye. Nonetheless, you need to be aware of the risks these ultraviolet rays can cause, depending on the wavelength used. From a simple sunburn to redness or conjunctivitis. Each category of ultraviolet is unique and has its own characteristics.
UV-A, THE ULTRAVIOLET THAT MAKES US TAN
Type A ultraviolet light (UVA) is the UV radiation that enables us to tan by penetrating deep into the skin, but is also responsible for pigmentation spots, skin aging and wrinkles. With a wavelength of 400 to 320 nanometers, this type of non-visible light accounts for 95% of the rays that reach the Earth's surface, and may be responsible for skin cancer in some people.
It's also worth noting that, unlike UVB, UVA rays pass through glass and can reach the skin when you're behind glass exposed to the sun.
UV-B, THE CAUSE OF MOST OF OUR SUNBURNS
With a wavelength of 320 to 290 nanometers, UVB rays, which also come from the sun's rays, make up 5% of the rays reaching our planet. Unlike UVAs, they penetrate the skin much less, and do not pass through glass or clouds. They are, however, responsible for sunburn, burns, blisters and the majority of skin cancers.
In view of their potency, all dermatologists recommend protecting yourself from them during exposure to the sun with a high-protection sun cream.
UV-C DISINFECTION
Type C ultraviolet rays, much less well known, are stopped by the ozone layer and do not penetrate our planet, making life possible on Earth. Located between 100 and 280 nanometers, this type of short-wave ray directly attacks the reproductive DNA of all types of virus and bacteria.
Artificially reproduced using ultraviolet light bulbs, this technology has been used in hospitals since the 70s, and more recently for disinfecting water, air and surfaces. water, air and surface disinfection. 99.99% effective against all types of virus and bacteria, this technology has become increasingly popular since the arrival of SARS-CoV-2 2, against which it is effective while respecting the environment.(See the study on UV-C efficacy).
Nevertheless, despite its obvious qualities, misuse of its UV rays can be hazardous to the eyes and skin of the human body in the event of exposure . Consequently, professional advice is recommended to minimize risks and achieve the desired disinfection.
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