A Study on the Solar UVA and UVB Doses at Kongju

Kim, Hyang Bae; Park, Jang Kyu

Abstract

An appreciation of daily and annual changes of ultraviolet radiation is important in order to optimize the conditions for climatic therapy of skin diseases or in order to minimize the harmful effects of the sun. Ultraviolet A(355nm) and ultrviolet B(290nm) doses were measured at Kongju from April to September, 1985, on two different weather conditions-clear and relatively clear. The followings were the summary of the findings. 1. On clear weather, UVA dose was peak at noon of the day and in June of the year. 2. On relatively clear weather, UVA dose was peak at 2 p.m. of the day and in July of the year. 3. UVB dose was peak at noon of July regardless of weather conditions. 4. In relatively clear weather the UVA and UVB doses decreased from those of clear weather by 29%, and 36% respectively. 5, The relative difference between the doses of UVA and UVB depended on the degree of solar zenith angle. The greater the solar zenith angle, the greater the difference. 6. In order to treat a patient with solar UVA radiation, therefore, it is suggested to have the patient expose himself to the sun around 10 a, m. and 3 p.m. to minimize the harmful effects of solar UVB. However, when one wants to treat with solar UVB radiation, it would be better to expose to the sun around noon.