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  • Most of us think of the Sun as our friend.


  • It helps plants grow, keeps us warm, and who doesn't love to lie on the beach on a sunny day?


  • But for all of it's good qualities, the Sun can also be harmful in large amounts.


  • That's why we invented sunscreen.


  • The purpose of sunscreen is to shield the body from the Sun's ultraviolet rays, which have several harmful effects, including sunburn, aging, and skin cancer promotion.


  • These rays are separated by their different wave lengths, into types such as UVA and UVB, which exert a variety of effects in the skin due to the absorption patterns of chromophores, the parts of the molecules responsible for their color.

    這些輻射光的分類因為不同波長而分散成 UVA (長波紫外線) 與 UVB (中波紫外線),這對皮膚產生了各種影響。因為在色基發色團的吸收模式中,其部分分子產生了顏色所造成

  • The primary two chromophores are hemoglobin, found in our red blood cells, and melanin, which gives our skin its pigment .


  • We know that UVB rays cause the skin to burn.

    我們知道 UVB 會導致皮膚曬傷

  • The role of UVA rays is less well understood and appears to have an effect on our tanning response, carcinogenesis, and aging.

    但對 UVA 就比較少了解了,它對皮膚造成影響,例如曬傷、癌症病變以及老化

  • So, how does the sunscreen protect us from these rays?

    那麼防曬乳如何保護我們 免於輻射光的危害呢?

  • There are two basic types of sunscreen, physical and chemical blockers.


  • Physical blockers, like zinc oxide or titanium dioxide, reflect the Sun's rays by acting as a physical barrier.


  • If you've seen lifeguards with noses covered in white, then you know what this looks like.

    如果你有看過救生員的鼻子上 塗了一層白白的東西,你就會知道物理性防曬的樣子

  • The same ingredients are primary components of diaper creams, where the goal is also to create a physical barrier.


  • Historically, they haven't always been easy to apply and were conspicuously visible on the skin, but new formulations have made this less of an issue .


  • Chemical blockers, on the other hand, absorb the Sun's rays.


  • They deteriorate more quickly than physical sunscreens because their ability to absorb the Sun diminishes.


  • Generally, these are more transparent when rubbed on the skin, but some people develop allergic reactions to some of the chemicals.


  • Regardless of the type of sunscreen, all are subjected to testing to determine their sunburn protection factor, or SPF.

    不管防曬乳的型態,所有的防護產品都需要經由測試來決定能防止曬傷的防曬係數,就是常見的 SPF

  • This is essentially a measure of the protectionthat the sunscreen will provide from UVB rays before one begins to burn.

    判斷防護能力的主要辦法是防曬乳能在你被曬傷前阻隔 UVB

  • But even if you don't burn, you still need to use sunscreen because unless you live in a cave, you're not immune to the effects of the Sun.


  • It is true that darker skinned people and those who tan easily have more built-in protection from sunburns, but they are still vulnerable to the effects of UVA.

    不可否認的是,皮膚比較黝黑的人,和那些容易曬黑的人比較不容易被曬傷,但他們還是會受到 UVA 的傷害

  • Children under the age of six months, on the other hand, should have almost no sun exposure as their protective mechanisms are not fully functioning, and their skin is more likely to absorb any sunscreen that is applied.


  • Wearing sunscreen helps protect against the development of all three types of skin cancer: basal cell carcinoma, squamous cell carcinoma, and melanoma.


  • On a daily basis, the DNA in your cells is developing mutations and errors that are generally handled by machinery within your cells, but ultraviolet rays from the Sun lead to mutations that the cell may not be able to overcome, leading to uncontrolled growth and eventual skin cancer.

    每天,細胞裡的 DNA 都會產生細胞運作可以控制的變異和差錯,但太陽的紫外線會導致細胞可能無法克服的變異,而產生無法控制的成長最後成為皮膚癌

  • The scariest thing about this is that usually you can't even see it happening until its too late.


  • But if these concrete risks to your health are not enough to convince you to use sunscreen, there are aesthetic reasons as well.


  • Along with cigarette smoking, sun damage is the leading cause of premature aging.


  • Photoaging from chronic sun exposure leads to a loss of elasticity in the skin, in other words, making it look saggy.


  • Take a look at this truck driver who's left side was chronically exposed to the sun and notice the difference.


  • This is an important point.


  • Car windows block UVB, the burn rays, but not UVA, the aging rays.

    車窗可以阻擋 UVB,燒燙的光,而不是 UVA,造成老化的光

  • It is recommended to use sunscreen daily, but you should pay special attention before prolonged sun exposure or when at the beach or among snow since the reflectivity of water and ice amplifies the Sun's rays.


  • For these cases, apply about an ounce fifteen to thirty minutes before you go out and once again soon after you get outside.

    如果是上述情況,外出前 15 分鐘到 30 分鐘塗抹大約一盎司的防曬乳,並在你出門後再次塗抹

  • After that, you should reapply it every two to three hours, especially after swimming or sweating.

    之後,你應該每 2 到 3 小時就重新塗抹一次,尤其是游泳或流汗之後

  • Otherwise you should wear protective clothing with ultraviolet protection factor, or UPF.

    否則,你也應該穿上有防曬係數 UPF 的防曬外套

  • Stay in shaded areas, such as under trees or an umbrella, and avoid the sun at the peak hours of 10 a.m. to 4 p.m.

    待在有遮蔽物的地方,像是大樹或雨傘底下,同時避免上午 10 點到下午 4 點間的烈日

  • And what's the best kind of sunscreen?


  • Everyone will have their preference, but look for the following things: broad spectra, SPF of at least 30, and water-resistant.

    每個人都有不同的喜好,但記得注意以下幾點:用途廣泛的、防曬係數至少 30,還有防水

  • A light moisturizer with SPF 30 should be good for daily use.

    有防曬係數 SPF30 的輕量潤膚霜蠻適合每天使用

  • Take note if you decide to use a spray.


  • They take several coats to effectively cover your skin, like painting a wall with a spray can versus a paint brush.

    噴霧需要不少塗層 才能有效蓋住你的皮膚,就像用噴漆的方式彩繪牆壁,與用油漆刷彩繪牆壁的不同

  • So, enjoy the sun, but enjoy it with sunscreen.


Most of us think of the Sun as our friend.



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B1 中級 中文 美國腔 TED-Ed 皮膚 太陽 曬傷 陽光 塗抹

【TED-Ed】為什麼要擦防曬乳? (Why do we have to wear sunscreen? - Kevin P. Boyd)

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    VoiceTube 發佈於 2019 年 01 月 19 日