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The UV Light Spectrum--UVA UVB UVC
11.08.2022 | YouWeMed Healthy Store | YOUWEMED Health Blog

The UV Light Spectrum

It is very important to understand the UV light in order to fully appreciate the benefits of UVB light therapy. There are three types of UV light, and each impacts the human body in a unique way.


UVA light (315nm to 400nm) has the longest ultraviolet wavelength and accounts for the majority of UV radiation that reaches Earth’s surface. About 95% of the sun’s rays are UVA. This is the wavelength that is associated with premature aging, wrinkles and skin cancer, as it penetrates deep into the layers of the skin. Tanning beds are primarily designed to emit UVA wavelengths to trigger melanin production, which darkens the skin. These forms of light treatments cause negative health consequences.


UVB light (280nm to 315nm), the “medium” wavelength, is mostly absorbed by the ozone layer. Roughly 5% of UVB rays reach Earth’s surface, and the intensity at which exposure occurs is dependent on season, geography, and time of day, among other factors. UVB light therapy has long been used to treat a variety of medical conditions, such as chronic skin conditions psoriasis vitiligo and vitamin D deficiency. Some therapies utilize a broad spectrum of UVB light while others emit a narrow range within the UVB spectrum to achieve specific health outcomes.


UVC light (100nm to 280nm) has the shortest wavelength and is the most harmful UV light. Exposure to UVC light is mostly avoidable, as this spectrum is almost completely absorbed by Earth’s atmosphere. If exposed to UVC light, you might expect severe burns at every point of contact.