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UVB & UVA [ ブログ ]

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The ultraviolet ray divides two kinds of UVB, UVA.

Injury and shelter of UVB have already got thorough research, it can make the skin sunburn, shine red (about 25 minutes for common people) within short time ,The sun-proof product of overwhelming majority is UVB type on the market now, SPF is a sign of UVB protective capacities.

UVA is a terrible sunshine killer, longer that it is making use of the wavelength, penetrate the ability with strong ability, can penetrate the top layer of skin, the tissue under the genuine leather of deep people, can destroy the collagen, very small structure within the skin such as the elastic fiber tissue, wrinkles and young line emerge, make skin relax oldly and feebly. This call photo-aging as at medical science.

In the sunshine in ultraviolet energy is distributed, UVA is 15 times that of UVB, and the main reason making skin tanned. It can make the sour content of transparent quality of combining water in the skin reduce, makes skin dry, accelerate the melanin and take shape, make the complexion darken, is the important reason which causes skin carcinoma at the same time.

People find sunshine UVA of the general intensity shines on the skin, nearly pass 2- 4 hours, skin can appear a steady one wicked to take, academy claim " lasting type immediately dark to take " .


What is called SPF value refer to products ability to protect UVB, that is to say, prevent skin from shine red ability to sunburn. Generally speaking, it is 20- 25 minutes that people's skin produces erythematous time under the circumstances that the sunlight penetrates directly, if one bottle prevents suntan lactic SPF value is 8, coated once with it, the protection time to the skin is 20 (25) *8= 160( 200) About minute. Concrete can consult the table below:

Service condition of SPF value

2- Sunshine in 8 winters, morning and evening of spring and autumn sunshine and overcast and rainy

9- Morning and evening of 20 summers and sunshine of medium-sized intensity

21- 30 outwork, strong sunshine of travel, summer

Greater than 30 Under the particular environment ' Such as plateau) ,The strong sunshine shines

Abroad, it pay attention to UVA the products sun-prooves often can find besides marking SPF value PA at pack " + " Words,it show they products last ability, it is last tanned ability not to that is to say. The products that generally have this identification are all sun-proof products that has just emerged, more advanced technically, see country product still at present. The meaning that PA value represents is as follows.

PA value protects time effectively

PA + about 4 hours

PA is ++ about 8 hours

PA +++ protects superstrongly

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