Ultraviolet radiation makes erythema that injures DNA of the human skin. The Environment Agency of Japan publishes a health guidance manual for ultraviolet radiation in June, 2003, and it is suggested to protect skin from the excessive ultraviolet radiation. Therefore, the ultraviolet radiation must measure to estimate the amount of exposure. The amount of skin exposure is calculated precisely by measuring the distribution of sky ultraviolet radiation spectrum. The distribution measurement of the ground ultraviolet reflection from the beach sand was carried.
