- UVB and UVA
UV is part of the ultraviolet spectrum from the sun to the earth, and its wavelength is shorter than visible light, so it’s invisible to the naked eye. Depending on the wavelength, UV can be divided into UVA, UVB and UVC. UVA is the longest wavelength, reaching 320-400 nm, UVB wavelength is 290-320 nm, and UVC was absorbed before in the Earth by ozone layer. UVA and UVB, which are not absorbed by the ozone layer, are exposed to the surface of the earth, causing damage to our skin, causing premature aging of the skin, causing damage to the eyes, and even causing skin cancer. They can also inhibit the immune system, weaken your ability to fight other diseases.
UVA is the life ultraviolet rays, through the window glass and clouds into the human skin, most of our life is exposed to UVA light, it occupied 95% of all the UV light to reach the Earth, although it does not So strong as UVB, but as long as there is sunlight, it will always exist, and maintain a balanced strength, so we should pay attention to the protection of UVA throughout the year.
UVB is outdoor UV, which directly into the skin when people in the outdoor activities. It is the main reason of skin red and tanning. It is mainly hurt the skin of the surface, and it also causes skin spots, aging, and leading to the culprit of skin cancer. But the intensity of UVB is changing with time and season, and the strongest time of UVB light is from 10 am to 4 pm every day from April to October, but it can hurt the skin all year round, especially in high altitude areas. And after being reflected by snow or ice, 80% of the UVB will be reflected back to the skin for secondary damage.
SPF, or sun protection factor, is designed to measure the sunscreen products against UVB light resistance.
As early as 1938, the chemist Franz Greiter produced the world’s first sunscreen product, called Gletscher Crème, but it had a very low SPF index. The SPF as a concept is widely used as a sunscreen product standard is from 1962 onwards.
SPF values ranging from 2 to 60, what is the difference? Let me give you an example, if you do not have any sun protection measures, after 20 minutes of exposure in the sun, you skin will turn red. And then assume that you use SPF15 sunscreen products, then 15 × 20 = 300, and that means it could let you keep in the sun for 300 minutes without sunburn, that is 5 hours. But SPF30 sunscreen products don’t mean two times of SPF15 protection. SPF15 sunscreen products can block 94% of the UVB, SPF30 sunscreen products can block 97% of the UVB, SPF45 sunscreen products can block 98% of the UVB, but no one can do 100% sunscreen effect.
The American Academy of Dermatology recommends that people use SPF15 or more sunscreen products, but not to say that the higher the value of, the better protection. SPF50 sunscreen products only has 1% to 2% of the protection ability more than SPF30 products.
- Choose a different sunscreen product
Because each person has different skin color, different skin requirements, different requirements for waterproof, so should choose a different, suitable for their own sunscreen products, but there is one thing that everyone should pay attention to, it’s better to choose sunscreen products which has both UVB and UVA. Many products can only resist UVB, in fact, UVA can give the skin a deeper level of damage. According to different situation, let’s look at how to choose sunscreen.
White skin – white skin is usually very easy to be sunburn, so first of all should choose SPF between 30-50 sunscreen products, the rest can be based on the different time in the outdoor to decide.
Skinny people – compare to white skin, this type of skin is hard to be sunburn, so after being sunburn may become lighter brown, and the choice of SPF15 above is the most appropriate.
Darker skin – dark skin texture doesn’t have much more possibility to be sunburn, the risk of skin cancer is also minimal, but this does not mean that no need of sunscreen products. The sun will not be different because of the skin color. So we need to pay attention. For this kind of skin, SPF15 sunscreen products are enough, the rest is according to your skin’s sensitivity, as well as the length of time to stay out of the room to adjust.
Different Skin Type
Oily skin – If you are oily skin, do not apply too much sunscreen products to yourself. This will cause excessive protection. You only need to use SPF15 or more.
Dry skin – dry skin is easy to have dry itch and dry spots, so you need to use the sunscreen products which have moisturizing ingredients, and choose it from SPF20 or more.
Acne skin – acne skin’s best choice is less oil, moisture content sunscreen products, so that the skin can absorb more water. Above SPF15 will be the best for acne skin.
Other skin types – If you have a lot of moles on your skin or suffer from some kind of skin disease, then you need to use SPF highest coefficient of the product, at least 50 or more. But to note that if you are suffering from a large area of skin diseases, then it’s better to ask the skin experts before you use sunscreen products.
Most of the sunscreen products sold on the market are for adults, but if you want to give children sunscreen, you must choose a product specifically for children, because adult sunscreen for children delicate skin may be too exciting. Remember that any sunscreen products cannot be used for infants less than 6 months. If you have to use it, ask your children doctor for advice.
If you are in the ordinary outdoor activities, then the general sunscreen products is enough, but if you always go out a lot of sweat, or go to the beach to swim, you may want to use a waterproof effect of the product. Some of the signs of waterproof products are Waterproof, some signs are Water-Resistant, both of which have different sunscreen times. Waterproof products has a longer protection time than the choice of water-resistant products, the former can make you in the water to get 80 minutes of protection, while the latter under the same conditions can only protect you 40 minutes. So if you go swimming, it is best to choose the waterproof products.
Precautions for Using Sunscreen Products:
- Should pay attention to the range of sunscreen, the American Academy of Dermatology recommended that people should “apply sunscreen products on all exposed skin”. Especially the nose, ears, sandals bare feet of these skin thinner place. And should pay attention to the amount of smear, if smear too thin will reduce the ability of sunscreen products to absorb UV light reflection.
- Apply sunscreen products for 20-30 minutes before going out, giving the skin plenty of time to absorb sunscreen products.
- If you sweat too much need to apply sunscreen again, then do not apply in the damp skin, it will affect the effect. Try to let the skin to the cool place to cool dry, wait 20-30 minutes and then smear, so as to achieve the best results.