What is UV-C?
Our eyes perceive only a part of the electromagnetic radiation emitted by the sun, which is in the so-called visible spectrum, in the wavelength range that goes from 400 to 700 nm. However, the sun emits energy within a wide range of wavelengths. Part of this radiation is ultraviolet or UV radiation.
Ultraviolet radiation is electromagnetic radiation with a wavelength shorter than visible radiation, but longer than X-rays. About 5% of the Sun's energy is emitted in the form of ultraviolet radiation. This can be harmful to living beings, so controlling these levels of solar radiation is very important for the development of outdoor activities.
Within the ultraviolet interval, three zones have been differentiated, A, B and C, from lower to higher energy, since their effects on living beings are very different:
Type A (UV-A) radiation is the closest to the visible radiation spectrum, the longest of the three wavelengths. It comprises the range of wavelengths between λ = 400 nm and λ = 320 nm, and is what produces the tan. It is very little absorbed by the atmosphere. Being low energy, it presents less danger than the rest of UV, although it can also cause premature aging of the skin.
Type B radiation (UV-B) is the intermediate region of the ultraviolet spectrum, between λ = 320 nm and λ = 280 nm in wavelength. It is partially absorbed by ozone, and small increases in the dose received can cause eye and skin damage, sunburn (redness of the skin) ranging from mild to severe burns. Overexposure for years to this radiation, in addition to causing premature aging of the skin, can cause skin cancers.
Type C (UV-C) radiation is the most energetic and the most damaging of the three, but it does not reach the Earth's surface as it is absorbed by the ozone layer of the stratosphere. It covers the area of the spectrum between λ = 280 nm and λ = 100 nm.
Why UV light kills COVID-19?
UV radiation, to a larger extent UVC, destroys the reproductive capacity of microorganisms due to photochemical changes in nucleic acids and to a lower level the proteins. It is a widely known method of disinfection and suitable for various types of viruses, including SARS-COV. The effectiveness of disinfection depends on several factors, such as the power of the radiation, the distance to the irradiated object, the areas unreached by direct radiation, the presence of proteins or other elements that absorb UV, among other more specific factors. Despite its limitations, it can be a method to combat COVID-19.
How to protect yourself from UV-C emissions?
UV radiation sources require proper precautions to ensure safe use. To this end, the Use and Application Guide provides general practices and recommended precautions for the use of UV radiation sources.
UV radiation is easily absorbed by clothing, plastic, or glass. Once absorbed, UV radiation is no longer active. Maintenance works or other situations where there is an interaction with UV radiation, it is recommended to wear personal protective equipment that covers all exposed areas.
Recommendations to work with UVC devices:
- Use face shields or safety glasses specifically designed to protect against these risks (European Standard EN166 and EN170). They exist in different colors (clear, yellow, gray) according to the protection offered by wavelength.
- Cover any exposed skin.
In case of exposure to UV rays, the following actions are recommended:
- Consult an ophthalmologist if eye damage is suspected.
- Treat skin lesions immediately.
- Follow your organization's incident reporting procedure. These often require documentation of the date and time of the incident, the people involved, the equipment involved, and the type of injury.