Among the different health benefits due to sun , its action on the well-being and psychological balance of many people is well known, or its role in the synthesis of vitamin D and in the treatment of some skin diseases. However, sun exposure can also have harmful effects : These can be immediate, with sunburn, which appears with redness, burning sensation and pain, edema (swelling), vesicles formation; There may be fever and digestive symptoms in more severe situations; Pimples and itching may appear, which worsen over the years; In the longer term, effects are aesthetic, such as wrinkles, blemishes, less skin elasticity, and in health, such as skin cancer. Not all people are equally sensitive to the effects of the sun and several factors vary the intensity of the ultraviolet solar radiation to which we are exposed. Knowing our sensitivity, what ultraviolet radiation is and what makes it vary, or consulting the ultraviolet index, helps us to better understand the need for protective measures and adapt it to our needs. Phototypes and sun sensitivity The phototype, or skin type , relates the color of the skin, hair, and eyes with sensitivity to the sun, the possibility of burns and the ability to tan. It should be used as an indication for the type of sunscreen to use, exposure time, need for protective clothing, glasses, among others. Six phototypes are considered, which have, briefly, the following characteristics: Phototype 1 - Light skin sometimes with freckles, blond or red hair, blue or green eyes, very sensitive skin that burns and does not tan; Phototype 2 - Light skin, blond hair, blue or green eyes, sensitive skin that tans slowly and burns easily; Phototype 3 - Light brown skin, dark blond or brown hair, eyes of variable color, skin slightly sensitive to the sun, that tans progressively; Phototype 4 - Dark skin, dark brown or black hair, brown eyes, skin with normal sensitivity, that tans and burns little; Phototype 5 - Dark brown skin, dark brown or black hair, brown eyes, skin that is not very sensitive to the sun, that tans and rarely burns; Phototype 6 - Very dark or black skin, black hair, dark eyes, skin that rarely burns and is the most resistant to the effects of the sun. Sunlight and ultraviolet radiation Radiation is the emission of energy from a source. There are many types of radiation, with different energy levels. Ultraviolet (UV) radiation has an intermediate energy level, is present in solar radiation, does not penetrate the body in depth, but can have serious effects on the skin . There are different types of ultraviolet radiation, including: UVA radiation , which is the least energy and represents about 95% of the ultraviolet solar radiation reaching the earth. It is more related to long-term signs of skin aging, but it is thought that has a role in skin cancer; UVB radiation , which has slightly more energy than UVA, represents about 5% of the ultraviolet solar radiation that reaches us. It causes skin burns and is thought to be the cause of most skin cancers. What causes the amount of solar UV radiation that affects the skin to vary? The ultraviolet radiation that reaches the skin depends on: Exposure time; Intensity of ultraviolet rays; Skin protection. The shorter the exposure time and the more protected the skin is, for example with protective clothing or products, the smaller the amount of UV radiation that reaches it. The intensity of the ultraviolet rays that reach the earth surface depends on factors such as: The hour: at solar noon, the radiation is more intense, the rays reach the earth perpendicularly and concentrated on a smaller area. For this reason, it is advisable to avoid exposure between 11 am and 4 pm, particularly in the most sensitive people; The season: in summer, the intensity of radiation is greater because the incidence of sunlight is also almost perpendicular to the earth; The altitude: the higher the height, the more UV rays reach the land; Latitude: the lower the latitude (which is 0º at the equator) the greater the intensity of the radiation; The presence of clouds: on cloudy days, ultraviolet radiation continues to reach the earth surface. The absence of heat sensation can give a false sense of security; Reflected radiation: UV rays can be reflected by surfaces such as water, sand, snow, among others, enhancing the effect of the exposure; The composition of the atmosphere: for example, the thickness of the ozone layer, because it filters out some ultraviolet radiation. UV Index The ultraviolet index, or UV index, is part of the weather forecast. It measures the intensity of ultraviolet rays in each geographic location, date, and time. It has values from 0 to 11+ , distributed in five categories, each associated with a color, risk level and general protection advice: 0-2.9 - green, low risk; 3.0-5.9 - yellow, moderate risk; 6.0-7.9 - orange, high risk; 8.0-10.9 - red, very high risk; 11.0+ - violet, extreme risk. On smartphones, information about the UV index can be found in the meteorology area . For Portugal, it can also be consulted on the website of the Instituto Português do Mar e da Atmosfera . Choosing sunscreen To minimize problems, in addition to avoiding places and times of greatest risk and wearing appropriate clothing and glasses, it is necessary to choose the appropriate sunscreen proper for age and phototype. Prefer those with protection values greater than 30 and that are water resistant; Repeat application according to the manufacturer instructions and considering perspiration and the number of baths. Children should deserve special care. They are less “equipped” to defend themselves and the relationship between excessive sun exposure and the number of signs they will have on the skin is proven. In children, sunscreen never replaces the protection of age-appropriate clothing, hat and glasses use. The idea that a sunscreen does not allow tanning, besides being wrong, is dangerous. In addition, tanning, that is considered a sign of health and is aesthetically pleasant, is a defense mechanism of the skin in the face of an aggression. Dermatology: the importance of individual counseling The multiple risk factors for skin diseases associated with ultraviolet radiation explain the importance of the intervention of dermatologists for an individualized assessment and prevention of these diseases. Individual risk factors are the phototype, the presence of numerous pigmented signs (melanocytic nevi), chronic immunosuppression (transplanted people). Behavioral risk factors include chronic sun exposure (professional or recreational), not using or using unsuitable sunscreens, and use of sunbeds. The assessment of risk factors, the prescription of the most appropriate sunscreen for each person, as well as specific recommendations, according to the clinical evaluation, can contribute to a good sunny vacation, minimizing the risks. It is also important no know Artificial tanning has the same risks as natural radiation, whether in terms of photoaging or skin cancer. Author : José Campos Lopes Meet the dermatology team from Hospital da Luz network. The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item.
