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 its 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 wavelengths 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. The primary two chromophores are hemoglobin, found in our red blood cells, and melanin, which gives our skin its pigment.
防曬品的功用是保護身體不受太陽的紫外線傷害，紫外線有許多有害的影響，包括曬傷、老化，以及增加罹患皮膚癌的可能。這些射線依照它們不同的波長被分成像是 UVA 和 UVB 這些種類，因為發色團的吸收模式，它們會對皮膚造成各種影響，發色團是分子中負責顏色的部分。兩種主要的發色團為血紅素，存在於我們的紅血球內，以及黑色素，黑色素讓我們的皮膚有顏色。
We know that UVB rays cause the skin to burn. The role of UVA rays is less well understood and appears to have an effect on our tanning response, carcinogenesis, and aging. So, how does the sunscreen protect us from these rays?
我們知道 UVB 射線使皮膚曬傷。 UVA 射線扮演的角色較無受到充分了解，而且似乎對我們的曬黑反應、癌症形成以及老化有影響。所以，防曬品怎樣保護我們不受這些射線的傷害呢？
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. 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. This is essentially a measure of the protection that the sunscreen will provide from UVB rays before one begins to burn. 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. 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.
無論防曬品類型為何，全都需要經測試來決定它們的防曬係數，或稱 SPF。這基本上是一種防護的測量，測量在一個人開始曬傷前，防曬品所能提供遠離 UVB 射線的防護。但就算你沒曬傷，你還是需要用防曬品，因為除非你住在洞穴裡，不然你還是會受到陽光的作用影響。沒錯，皮膚較黝黑和那些容易曬黑的人對曬傷有更多內建的防護，但他們還是會被 UVA 造成的影響傷害。另一方面，六個月大以下的孩童應該幾乎不要曝曬在陽光下，因為他們的防護機制尚未完全作用，而且他們的皮膚很有可能吸收任何塗上的防曬品。
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. The scariest thing about this is that usually you can't even see it happening until it's too late.
塗抹防曬品有助避免所有三種類型的皮膚癌生成：基底細胞癌、鱗狀細胞癌，以及黑色素瘤。每天，你細胞中的 DNA 都在發生突變和失誤，那些突變和失誤通常是由你細胞中的「裝置」處理，但來自太陽的紫外線引起細胞可能無法戰勝的突變，結果導致無法克制的增長，最後導致皮膚癌。關於這最可怕的事是，你甚至不太會察覺事情的發生，直到一切為時已晚。
But if these concrete risks to your health are not enough to convince you to use sunscreen, there are aesthetic reasons as well. 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 whose 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.
但假如這些對你健康造成的具體風險還不夠說服你使用防曬品的話，還有一些和審美有關的原因。除了吸菸外，太陽造成的傷害也是提前老化的主要成因。長期陽光下曝曬引起的光老化導致皮膚彈性流失，換言之，使皮膚看起來鬆垮垮的。看看這位卡車司機，他的左側長期曝曬在陽光下，注意那差異。這是很重要的一點。車窗阻隔 UVB－－使人曬傷的射線，但沒有阻隔 UVA－－使人老化的射線。
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 15 to 30 minutes before you go out and once again soon after you get outside. After that, you should reapply it every two to three hours, especially after swimming or sweating. Otherwise, you should wear protective clothing with Ultraviolet Protection Factor, or UPF. 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.
人們建議每天使用防曬品，但你在長時間的陽光曝曬前應該特別注意，或是當你在沙灘，或雪地上時都要特別注意，因為水和冰的反射率強化了太陽發出的射線。這些情況下，在你出門前的 15 到 30 分鐘抹上約一盎斯(約 28 cc)的防曬品，並在你到外面不久後再塗一次。在那之後，你應該每二到三小時再塗一次，特別是在游泳或流汗後。不然的話，你就應該穿上有紫外線防護係數(或稱 UPF) 的衣服。待在陰影處，像是樹下或傘底下，並在早上十點到下午四點陽光最毒的時間避開太陽。
And what's the best kind of sunscreen? Everyone will have their preference, but look for the following things: broad spectrum, SPF of at least 30, and water-resistant. A light moisturizer with SPF 30 should be good for daily use. 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.
那最棒的防曬品類型是哪種呢？每個人都有自己的喜好，但找找以下特性：廣效性防曬、防曬係數至少 30 ，還有防水。防曬係數 30 的清爽防曬乳應該就夠日常使用了。如果你選擇使用防曬噴霧請注意。防曬噴霧要上好幾層才能有效地覆蓋你的肌膚，就像用噴漆罐對上用油漆刷來塗一面牆壁一樣。
So, enjoy the sun, but enjoy it with sunscreen.
- 「認為...是...」- Think Of...As
Most of us think of sun as our friend.
- 「始免受、防護」- Protect...From
So, how does the sunscreen protect us from these rays?
- 「充當、擔任」- Act As
Physical blockers, like zinc oxide or titanium dioxide, reflect the sun's rays by acting as a physical barrier.
- 「另一方面」- On The Other Hand
Chemical blockers, on the other hand, absorb the sun's rays.