Overexposure to UV radiation affects the skin, eyes, and probably the immune system. Many people forget that the effects of exposure to UV radiation accumulate over a lifetime. However, there may be other pathways of action of ultraviolet (UV) radiation in humans, as described in this review. One of them is the induction of cosmetic tanning (immediate darkening of pigments, persistent darkening of pigments and delayed tanning).) .Delayed tanning induced by UVB rays (increases melanin in the skin after several days) acts as a sunscreen.
Several human skin diseases, such as psoriasis, vitiligo, atopic dermatitis and localized scleroderma, can be treated with solar radiation (heliotherapy) or artificial UV radiation (phototherapy). Exposure to UV rays can suppress the clinical symptoms of multiple sclerosis regardless of vitamin D synthesis. In addition, UV rays generate nitric oxide (NO), which can lower blood pressure and, in general, improve cardiovascular health. NO induced by UVA rays can also have antimicrobial effects and, in addition, act as a neurotransmitter. Finally, exposure to UV rays can improve mood by releasing endorphins.
Damages the immune system: Excessive exposure to UV radiation has a detrimental suppressive effect on the immune system. Scientists believe that sunburn can change the distribution and function of disease-fighting white blood cells in humans up to 24 hours after exposure to Sun. Repeated overexposure to UV radiation can cause even more damage to the body's immune system. The immune system defends the body against bacteria, microbes, viruses, toxins, and parasites (diseases and infections).
To see how well the immune system works, look at how quickly something deteriorates when it dies and the immune system stops working. Skin cancer is the most common cancer in the United States. The two most common types of skin cancer are basal cell cancer and squamous cell cancer. They usually form on the head, face, neck, hands and arms because these parts of the body are the most exposed to UV radiation.
Most cases of melanoma, the deadliest type of skin cancer, are caused by exposure to UV radiation. In the electromagnetic spectrum, UV light has shorter wavelengths than visible light, so the eyes can't see UV rays, but the skin can feel them. Improves vision for some animals: Some animals (including birds, bees, and reptiles) can see through nearby ultraviolet light to locate many ripe fruits, flowers, and seeds that stick out more strongly from the background. Weakens plastics: Many polymers used in consumer goods (including plastics, nylon, and polystyrene) break down or lose strength due to exposure to UV light.
Damages the eyes: prolonged exposure to UV rays or high-intensity UV rays (for example, on sun loungers) damages eye tissues and can cause a “burn” on the eye surface, which is called “snow blindness” or photokeratitis. Indoor tanning is popular, not only among Caucasians in countries with low annual UV radiation levels (northern countries) ,16,17, but also in countries with high annual UV radiation levels (Australia). Agees the skin: UV rays accelerate skin aging, as they destroy the collagen and connective tissue that lie beneath the top layer of the skin.