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Analyses the harm of ultraviolet (uv) knowledge
The harm of ultraviolet (uv)
People know that ultraviolet ray direct illuminate skin, besides have antiseptic effect, still have to adjust and improve nerve, endocrine, digestion, circulation, respiration, blood, immune system, and promote the function of vitamin D production. However, in recent years, people gradually realized that excessive ultraviolet photochemical reaction, a series of changes can make the function of the body, especially to the human body skin, eyes and immune system damage. In recent years in the United States, Canada, Australia and other countries and some cities in our country, has begun releasing the uv index forecast, to remind the public to take corresponding
Protective measures. A few days ago, the world health organization experts called for people to engage in outdoor activities to avoid long time exposure in the sun, to the beach and the mountains on vacation pay particular attention to protect the skin.
The effects of ultraviolet radiation to the human body skin and eyes. The skin to absorb ultraviolet light to the wavelength. The shorter the wavelength, penetrate into the skin depth, the smaller, less melanin calm after irradiation; The longer the wavelength, penetrate into the skin depth, the greater the melanin and stronger after irradiation. Due to the effect of photochemical reaction, energy level high photon flow can cause degeneration of intracellular nucleoprotein and some enzymes. After ultraviolet radiation, therefore, should be after the incubation period of 6 to 8 hours to change in cells and onset of symptoms, including skin dry, pain, skin shrivel, sparkling even fall off. As ultraviolet penetration to the organization is very weak, under the skin less deep tissue injury. But can cause severe ultraviolet (uv), body fatigue, low thermal, sleepiness and systemic reactions. Some people's skin due to allergic to ultraviolet ray, after light solar dermatitis (also called a sunburn), exposed areas of skin itching, tingling, skin desquamation, possibly dyke break crusts. Actual observations show that at an altitude of 3500 meters of plateau (uv usually 3-4 times of the plains), bare skin around noon under uv light, for 20-40 minutes, skin burning sensation and peeling; 40-80 minutes, the skin will be pimples blisters and lead to a variety of pathological changes.
Long-term, repeated exposure, can cause the skin and mucous membrane of solar sex keratinization disorder (light Angle disorder), performance in the exposed parts (such as forehead, cheeks, nose, lips, eyelids and conjunctival) in single and multiple flat Angle layer thickening. According to medical analysis, this is a kind of precancerous change. Studies have shown that uv light can cause deoxyribonucleic acid (DNA) in the nuclei of damage, because the body internal defects, the cell can not to damage the DNA repair, thus occurred to the variation of DNA replication, if the body's immune system is not rejection in time, to clear the mutation of cells, namely defective immune surveillance function, the variation of DNA cells to proliferate and eventually lead to the formation of tumor, therefore, ultraviolet ray is the skin of an important factor in cancer.
Since 1980, the United States diagnosed with melanoma and significantly increased the number of non melanoma skin cancer and cataracts, similar situations have appeared in many other countries. According to the American cancer society estimates, the United States in 1995 diagnosed with basal cell or a total of 800000 patients with squamous cell carcinoma, melanoma skin cancer is about 34000 people. According to the national cancer institute, points out that since 1973, the incidence of melanoma skin cancer each year increased by 4%. It is estimated that 9300 people in 1995 cancer deaths, 7200 of human malignant melanoma skin cancer, 2000 other skin cancer.
The part of the eye is most sensitive to uv light. Study shows that the wavelength of 230 nanometers ultraviolet ray can be completely for corneal epithelium absorption, for 280 nanometer uv wavelength on the cornea injury force is the largest. Wavelength of 290-400 nanometer near ultraviolet light can cause damage to the lens, is one of the pathogenic factors of senile cataract.
Under strong ultraviolet region, the effect is very obvious. , such as in low latitudes, because the Angle is greater than the higher latitudes, sunshine time is long, and at high altitudes, due to the thin air, little clouds of dust grains, atmosphere and to face less uv absorption, have increased ultraviolet radiation, therefore, these areas of relatively high incidence of cataracts; In the sunlight shining on the sea or desert long-term observation observation of soldiers, sailors, appear very dark adaptation ability decline phenomenon; Snow mountain plateau in the thin air staff, due to the snow surface strongly reflects the light of ultraviolet radiation damage, susceptible to snow blindness; People in the snow, the desert, or on the surface of the exposure time is too long, because of the strong ultraviolet radiation, susceptible to solar sex eye inflammation.
In July 1994, the world meteorological organization held a uv index expert meeting. Meeting made the guidance of the uv index standards, the world meteorological organization uv index standard unit. According to the national weather service, uv index value, the U.S. environmental protection agency to skin disease, eye experts and relevant organization consultation, on the basis of considering the uv index value, different skin types and corresponding public "skin red minutes", identified the five types of exposure and proposed the corresponding protective Suggestions, such as the use of skin care, protective coat and hat, sunglasses, especially when every 10 to 16 to avoid in the hot sun exposure, etc.
Alert to the dangers of uv
Too much sunlight ultraviolet irradiation, but to the human body skin, eyes and immune system damage. Ultraviolet rays can damage human body skin cells, make skin prematurely senile. Serious when sunlight dermatitis namely sunburn or skin and mucous membrane solar sex keratinization disorder, cause cancer. The part of the eye is most sensitive to uv light, ultraviolet light can cause damage to the lens, is one of the pathogenic factors of senile cataract. In scorching summer, at 10 a.m. to 3 p.m. During this time, the ultraviolet ray in sunshine, the strongest outdoor activities to avoid this period of time. Please don't forget to hold umbrellas when outdoor activity, wearing a sun hat and sunglasses, using skin care factor, sunscreen, and try to wear light color clothes, in order to reduce the exposure to the sun's ultraviolet rays.