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On the positive side, UV exposure enables the synthesis of vitamin D 3, which is essential for bone health [1] and potentially plays a role in inhibiting certain cancers. [ 2 ] [ 3 ] While vitamin D can also be obtained through dietary supplements, [ 4 ] UV exposure offers benefits such as enhanced subdermal nitric oxide production and improved ...
Signs are often used to warn of the hazard of strong UV sources. The eye is most sensitive to damage by UV in the lower UVC band at 265–275 nm. Radiation of this wavelength is almost absent from sunlight at the surface of the Earth but is emitted by artificial sources such as the electrical arcs employed in arc welding.
The UV index is a number linearly related to the intensity of sunburn-producing UV radiation at a given point on the Earth's surface. It cannot be simply related to the irradiance (measured in W / m 2 ) because the UV of greatest concern occupies a spectrum of wavelengths from 295 to 325 nm, and shorter wavelengths have already been absorbed a ...
Blue light, a type of high-energy light, is part of the visible light spectrum. High-energy visible light (HEV light) is short-wave light in the violet/blue band from 400 to 450 nm in the visible spectrum, which in artificial narrowband form has a number of proven negative biological effects, namely on circadian rhythm and retinal health (blue-light hazard), which can lead to age-related ...
Exposure to optical radiation can result in negative health effects. All wavelengths across this range of the spectrum, from UV to IR, can produce thermal injury to the surface layers of the skin, including the eye. When it comes from natural sources, this sort of thermal injury might be called a sunburn.
Photokeratitis can be prevented by using sunglasses or eye protection that transmits 5–10% of visible light and absorbs almost all UV rays. Additionally, these glasses should have large lenses and side shields to avoid incidental light exposure. Sunglasses should always be worn, even when the sky is overcast, as UV rays can pass through ...
The bright light overwhelms the retinas of the eyes and generally gradually fades, lasting anywhere from a few seconds to a few minutes. However, if the eyes are exposed to a high enough level of light, such as a nuclear explosion, the blindness can become permanent. Flash blindness may also occur in everyday life.
A person with photic retinopathy may notice an impairment in their vision, for example a spot that does not go away after a reasonable recovery time, or blurring. They may also have eye pain or headaches. Vision impairment is usually in both eyes, but can be in just one. Impairment of a person with 20/20 vision usually ends up being about 20/40 ...