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

陽光滋養植物成長、讓我們感到溫暖，且誰不喜歡在陽光普照的日子裡，躺在沙灘上曬太陽呢？

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

但就算太陽有很多正面的優點，但是太亮的陽光也可能會造成傷害

That's why we invented sunscreen.

這就是發明防曬乳的原因

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.

防曬乳的功用是保護皮膚隔離太陽的紫外線。紫外線有不少害處，包含曬傷、皮膚老化，也可能造成皮膚癌

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 .

主要的兩個色基是血紅素，在血液細胞中可發現，以及黑色素，在我們的皮膚上產生色素

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.

常見的防曬乳有兩類，物理性防護和化學性防護

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

物理性防護，像是氧化鋅或是二氧化鈦，藉由物理性阻隔物，反射了太陽的輻射光

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.

相同的成分主要用來製作嬰兒用的痱子粉，目的是要用來產生物理性阻隔物

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 .

照理說，物理性防曬並不容易塗抹，而且在皮膚上可明顯被看到，但新的配方已經不會造成以上問題

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

另一方面，化學性防護吸收了太陽的輻射光

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

它比物理性防曬乳更快退掉傷害，因為化學防曬吸收太陽光的能力會隨時間減少

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

一般而言，化學防曬塗抹在皮膚上比較透明，但也造成有些人對某些化學成分的過敏

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.

但即使你並未感到皮膚燒燙，你仍須使用防曬乳，因為除非你住在洞穴裡，不然你對太陽所產生的影響沒有免疫力

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.

另一方面，六個月以下的孩童應該盡量避免太陽直曬，因為他們身體上的保護機制還未完全產生作用，以至於孩童的皮膚更容易吸收塗抹在皮膚上的防曬乳

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

塗抹防曬乳可以加強保護，避免三種皮膚癌產生：基底細胞癌、鱗狀上皮癌、黑色素瘤

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.

最可怕的情況是，你不太會看到這一切變化的過程，直到為時已晚

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

但如果這個危害到健康的事實還不足以說服你使用防曬乳，還有審美觀的原因

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

除了吸菸以外，陽光傷害是造成提早老化的主因

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

長期在陽光下曝曬所產生的皮膚老化導致皮膚失去彈性，另外，也讓皮膚看起來下垂

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

看看這位卡車司機，他的左側長期在陽光下曝曬，你可以看出兩邊的差異

This is an important point.

這是一個很重要的要點

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.

建議每天都使用防曬乳，需要特別注意的是，在長時間的陽光曝曬之前，或是待在海邊、在雪地中，因為水和冰也會反射太陽輻射光

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?

哪個是最好的防曬乳？

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.

如果要使用防曬噴霧，請記得

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.

所以，享受太陽吧！但記得用防曬乳