A dermatologist from Huashan teaches you how to fully protect yourself from sun damage. Ultraviolet rays are a type of carcinogen. High temperature | Skin | Ultraviolet rays

At present, it is the hottest season of the year, coupled with the global El Ni ñ o climate pattern, many people are suffering from high temperatures or even extreme heat.

Ultraviolet radiation has been classified as a carcinogen by the International Agency for Research on Cancer of the World Health Organization. Effective sun protection and skincare are particularly important this summer.

UVA let a person long wrinkles, UVB put the skin sunburn

Ultraviolet radiation is a part of sunlight, divided into long wave ultraviolet radiation, medium wave ultraviolet radiation, and short wave ultraviolet radiation.

The wavelength of UVA is approximately 320nm to 400nm, and it cannot be absorbed by the ozone layer of the atmosphere. It has strong penetrating power and can penetrate glass, directly reaching the dermis and subcutaneous tissue of the skin, damaging collagen fibers and elastic fibers. UVA is the main cause of skin aging, dark spots, and wrinkles.

The wavelength of UVB ranges from 280nm to 320nm, and most of it can be absorbed by the ozone layer. Its penetration is weaker than that of UVA, and it can be blocked by glass, reaching the epidermal layer of the skin, causing redness and, in severe cases, blisters. What we commonly refer to as sunburn is caused by UVB.

The wavelength of UVC ranges from 100nm to 280nm, and it is basically absorbed by the ozone layer without directly causing harm to the skin.

Suntanning is the skin's self-protection

What are the hazards of ultraviolet radiation on the skin?

One is photoaging. After long-term exposure to ultraviolet radiation in sunlight, the skin will age or accelerate aging, which is known as photoaging, and its severity far exceeds the natural aging caused by age. Research has shown that 80% of skin aging is caused by photoaging. The main manifestations of photoaging are rough, loose skin, pigmentation, wrinkles, and may be accompanied by obvious dryness, scaling, etc.

The second is sunburn. This is an acute damaging reaction caused by prolonged exposure of the skin to strong light. It usually occurs 6 to 24 hours after irradiation, and the skin at the exposed area will show edematous erythema accompanied by a burning sensation. In severe cases, blisters, blisters, and ulcers may appear, and the symptoms can last for 3 to 7 days. Usually, after one week, the skin of the sunburned area will show pigmentation and peeling.

The third is tanning. When ultraviolet radiation is applied to the skin, in order to protect itself, the melanocytes in the basal layer generate a large amount of melanin, forming a "protective shield" to absorb ultraviolet radiation. When the generation rate of melanin is greater than the degradation rate of melanin, it is easy to cause pigment deposition, which usually lasts for weeks or months.

The fourth is skin cancer. Long term exposure to ultraviolet radiation may cause damage to the DNA structure of the skin, leading to a decrease in skin immune function and ultimately resulting in precancerous lesions or skin cancer. Ultraviolet radiation has been classified as a carcinogen by the International Agency for Research on Cancer of the World Health Organization, and numerous studies have confirmed a clear relationship between ultraviolet radiation and the occurrence of various skin cancers. The highest incidence rate is basal cell carcinoma, followed by actinic keratosis, which is a precancerous lesion and may further develop into squamous cell carcinoma. Another type is malignant melanoma, which has the highest degree of malignancy and is most likely to metastasize to other organs.

The fifth is photosensitive skin disease. This type of disease only occurs in a small number of people who are highly sensitive to ultraviolet radiation. Common types include polymorphous solar rash, chronic actinic dermatitis, solar urticaria, and photogenic prurigo.

In addition, ultraviolet radiation can also promote or cause the aggravation of some diseases, such as melasma, lupus erythematosus, dermatomyositis, follicular keratosis, etc.

The higher the sun protection index, the better

So, how can we resist the damage of ultraviolet rays to the skin?

Firstly, try to avoid the period when the ultraviolet rays are strongest. Try to avoid outdoor activities from 10am to 4pm, as UV radiation is most intense and causes the greatest damage to the skin. If it is necessary to go out, try to choose a cool place to walk. In addition, high altitude, snow reflection, and water reflection can also increase the risk of exposure to sunlight, and prolonged exposure to these environments should be avoided or reduced as much as possible.

Secondly, it is important to choose the right sun protection clothing and sunscreen. Generally speaking, we use the UV protection coefficient to evaluate the ability of clothing to provide UV protection. A UPF rating of 15 to 24 indicates good protection, UPF25 to 39 indicates very good protection, and UPF40 to 50 indicates excellent protection. Sunscreen clothing can be made of tightly woven fabrics, such as white cotton or other non transparent ordinary fabrics. For sun hats, it is recommended to choose fabrics with good breathability, but they should not be transparent. It is recommended to choose a wide brim as much as possible. Try to choose a sunshade umbrella with a large surface and a black or dark interior.

When choosing sunscreen, broad-spectrum sunscreen should be chosen, which is a product that can block both UVA and UVB radiation at the same time. The SPF index of sunscreen represents its ability to protect against UVB radiation, while the PA index represents its ability to protect against UVA radiation.

Is it best to directly choose the sunscreen product with the highest SPF value and the highest PA "+"? Actually, it's not the case. Although the higher the SPF value, the better the sun protection effect of products with more PA "+", it also means that the added sunscreen content is higher or the ingredients are more complex. Overuse may increase the burden on the skin and even cause skin adverse reactions.

We should choose appropriate sun protection products according to the environment. When exercising indoors or outdoors on cloudy days, it is recommended to use sunscreen products with SPF15 to 30, PA+or PA++. It is recommended to use sunscreen products with SPF 30 to 50, PA+++, or PA+++when working directly in the sunlight. In environments such as snowy mountains, beaches, and plateaus, it is recommended to choose SPF50+, PA+++sunscreen products. If activities can cause excessive sweating or contact with water, waterproof and sweat resistant sunscreen products should be chosen.

Choosing sunscreen products should also be based on one's own skin type. For those with oily skin or acne on the face, they should choose water-based, oil-free sunscreen products with strong penetration. For those with dry skin, they can choose to use sunscreen with moisturizing texture and added moisturizing effects.

The correct application method is also crucial in the use of sunscreen. Apply in sufficient and even amounts. For the face, it is generally necessary to apply an amount the size of a 1 yuan coin. If active in sunlight for a long time, it is recommended to reapply every 2 to 3 hours to ensure continuous sun protection.

Finally, don't forget to clean after sun protection. Lightweight and non waterproof products can be cleaned with facial cleanser. For waterproof and sweat resistant sun protection products, it is recommended to use makeup removers for cleaning.

The first step after the sun to cold compress

After exposure to sunlight, the skin temperature rises and sensitive skin may turn red. So the first step after sunburn is to "cool" the skin. You can choose tap water, physiological saline, or iced milk to apply local cold compress for 10 to 20 minutes, repeated multiple times, to reduce local temperature and alleviate inflammatory reactions.

Once severe sunburn occurs, such as widespread blisters, blisters, or even systemic symptoms, it is necessary to seek medical attention promptly. In addition, after exposure to sunlight, it is necessary to do a good job of hydration and moisturizing to promote the repair of the skin barrier.

The skin is the largest organ in the human body and the first line of defense against external invasion. Sunscreen is an important part of protecting skin health. It is not only a necessary task in summer, but also necessary throughout the year on sunny and rainy days.