UV solar radiation in Brazilian cities: A perspective to the ideal time for healthy solar exposure

The UV solar represents less than 10% of the total solar radiation. The main biological effects of UV are the health benefits - vitamin D synthesis, and health risks - damage to cells and DNA as erythema and skin cancer. The aim of this article is to investigate the relationship between UV and global radiation in low and mid-latitudes Brazilian cities and impacts on the ideal time for exposure to vitamin D synthesis. UV radiation have been used to demonstrate the hourly and seasonal variation in João Pessoa/PB (7º S) and Florianópolis/SC (27° S). Results show a high positive correlation between global and UV radiation. In low latitude, the UV present higher differences compared with the one in mid-latitude that there was greater hourly variability. The peak of UV happened around midday (11 am to 1 pm) in both cities with a higher difference in João Pessoa. According to period that could be produce the vitamin D (SEA>20°), it starts before 7 am in all seasons in João Pessoa and at 7 am in the summer and 9 am in the winter in Florianópolis. This study evaluates the periods of low and high UV and alerts to the period of sun exposure aimed at the production of vitamin D and skin damage, since the literature recommends avoiding exposure after 10 am. This investigation contributes to a better understanding of the incidence of UV and adaptations in locations with similar latitudes and climatic characteristics.