Exposure to ultraviolet light, UVA or UVB, from sunlight has substantial effect on the skin, causing premature skin aging, skin cancer, and other skin changes. Ultraviolet wavelengths of 290 to 310 nm from the UVB band of radiation and of 320 to 400 nm from the UVA constitute the principal tissue-damaging rays of the sun that are not fully atmospherically filtered. An hour's exposure to the summer sun and its damaging rays can produce a painful burn with a characteristic erythema. The skin has natural mechanisms to prevent or minimize such sun-induced trauma, but it takes time to set these into place. Upon stimulation by ultraviolet rays, particularly longer, lower-energy rays above 320 nm, melanocytes at the epidermal-dermal junction produce the pigment melanin. Melanin's synthesis begins in the corpus of the melanocyte, with forming pigment granules migrating outward to the tips of the long protrusions of these starlike cells. Adjacent epidermal cells endocytotically engulf these projections. Through this cellular cooperation melanin, which absorbs and diffracts harmful ultraviolet rays, becomes dispersed throughout the epidermis and a person tans, with the person's capacity to sunburn declining accordingly. It should be realized that tanning takes time, several days in fact, and is incapable of protecting a person on first exposure. Damaging ultraviolet exposure also stimulates epidermal cell division and thickening of the epidermis (acanthosis). Such thickening, too, takes several days. When affected, it also lends protection to the underlying tissues.
Pharmacists should tell their sun-deprived, fair-skinned patrons not to spend more than 15 to 20 minutes in the midday sun (10:00 a.m. to 3:00 p.m.) on first exposure when traveling to vacation spots such as Florida (17). This is ample, safe exposure to initiate the tanning response in those who are able to tan. Exposures can be increased incrementally by 15 minutes a day until a 45-minute tolerance is developed, which is generally an adequate level of sun protection in conjunction with the use of sunscreens. It should be obvious that dark-skinned people are already heavily pigmented and thus far less susceptible to burning. Other individuals do not tan at all and must apply sunscreens with high protection factors before sun bathing.
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Rosacea and Eczema are two skin conditions that are fairly commonly found throughout the world. Each of them is characterized by different features, and can be both discomfiting as well as result in undesirable appearance features. In a nutshell, theyre problems that many would want to deal with.