<P> The differential effects of various wavelengths of light on the human cornea and skin are sometimes called the `` erythemal action spectrum . '' . The action spectrum shows that UVA does not cause immediate reaction , but rather UV begins to cause photokeratitis and skin redness ( with Caucasians more sensitive ) at wavelengths starting near the beginning of the UVB band at 315 nm , and rapidly increasing to 300 nm . The skin and eyes are most sensitive to damage by UV at 265 -- 275 nm , which is in the lower UVC band . At still shorter wavelengths of UV , damage continues to happen , but the overt effects are not as great with so little penetrating the atmosphere . The WHO - standard ultraviolet index is a widely publicized measurement of total strength of UV wavelengths that cause sunburn on human skin , by weighting UV exposure for action spectrum effects at a given time and location . This standard shows that most sunburn happens due to UV at wavelengths near the boundary of the UVA and UVB bands . </P>
<P> The differential effects of various wavelengths of light on the human cornea and skin are sometimes called the `` erythemal action spectrum . '' . The action spectrum shows that UVA does not cause immediate reaction , but rather UV begins to cause photokeratitis and skin redness ( with Caucasians more sensitive ) at wavelengths starting near the beginning of the UVB band at 315 nm , and rapidly increasing to 300 nm . The skin and eyes are most sensitive to damage by UV at 265 -- 275 nm , which is in the lower UVC band . At still shorter wavelengths of UV , damage continues to happen , but the overt effects are not as great with so little penetrating the atmosphere . The WHO - standard ultraviolet index is a widely publicized measurement of total strength of UV wavelengths that cause sunburn on human skin , by weighting UV exposure for action spectrum effects at a given time and location . This standard shows that most sunburn happens due to UV at wavelengths near the boundary of the UVA and UVB bands . </P>
which wavelengths of radiation are likely to cause photokeratitis
which wavelengths of radiation are likely to cause photokeratitis
starting near the beginning of the UVB band at 315 nm , and rapidly increasing to 300 nm
starting near the beginning of the UVB band at 315 nm , and rapidly increasing to 300 nm