thinkstock_rf_photo_of_woman_applying_lotion_beach  

webMD做的小測驗:

1.All sunscreens protect your skin from wrinkles, age spots, and sunburn.

所有的防曬霜都可以讓你的肌膚免於晒傷、皺紋和斑點?

錯:

Some sunscreens protect against only UVB rays, which are the primary cause of sunburn, but UVA rays penetrate deeper into your skin. Both UVB and UVA exposure can lead to premature skin aging, skin cancer, and sunburn. 

Only sunscreens labeled as both "Broad Spectrum" and "SPF 15" (or higher) can reduce the risk of skin cancer, and reduce the risk of early skin aging -- if they’re used regularly, as directed, and in combination with other sun protection measures that will help prevent sunburn. (The SPF – sun protection factor -- rating refers only to the level of protection from UVB rays, not UVA rays.)

防曬霜主要標示都是擋住UVB的指數,對肌膚來說,立即性的晒傷是UVB,但是讓你皮膚產生黑點的,卻是uva,儘管UVA和UVB都會導致皮膚癌,但是一般你看到的SPF指的都是對於UVB的防護能力,你可以參考這邊:

認識防曬係數,了解正確防曬原則

另外提醒,如果只是用了高UVA防護的產品,但是沒有防護好UVB(雖然這樣的產品不多),還是會晒黑,因為UVB所顯現的晒黑結果只是比UVA晚一點,並不是說UVB就不會刺激產生黑斑。
 
2.In 2012, the FDA will require warning labels on sunscreens that have not been shown to protect against skin cancer or early skin aging?
2012年起,FDA要求防曬霜標示本產品無法防止皮膚癌的發生
 
是的:
Beginning in 2012, sunscreens that aren’t both broad spectrum andSPF 15 (or higher) must carry a warning label that states: “These products have not been shown to protect against skin cancer and early skin aging. They have been shown only to help prevent sunburn.”
當防曬產品的SPF不足15或是防曬程度不夠時,必須標示這個產品可能無法防止皮膚癌,可以宣稱預防晒傷而已。
 
3.A base tan can help protect your skin from the sun.
把皮膚晒成棕色可以保護你免於晒傷?
 
錯:
There's no such thing as a safe tan; any sun exposure subjects your skin to damaging ultraviolet rays. Any time you tan, you damage your skin, increasing your risk for skin cancer and accelerating your skin's aging process.
並沒有這種事情,當你先把皮膚烤成棕色時,他就已經受傷了。
 
4.Makeup can help protect your skin from the sun.化妝可以讓你的肌膚避免晒傷?
基本上是這樣沒錯:
Compressed powder contains tiny pigmented talc particles that provide a certain amount of protection, and some moisturizers, eye creams, foundations, and lipsticks have SPF ratings of 15 and higher. Avoid shiny, high-gloss lipsticks, which can act like baby oil, attracting UV rays to your lips. If you want the wet look, apply a colored lipstick first, then top with the gloss.
多數彩妝商品除了本身具有的礦物或金屬粒子可以防止晒傷以外,部分商品也會有標示SPF,但是單純增亮,油光性的商品,像是嬰兒油、唇蜜,可能就不會避免晒傷了。
如果你還是想讓嘴唇看起來亮亮的,可以先上有防曬功能的底唇。
 
5.What percentage of the sun's UV rays can pass through clouds?大約多少比例的紫外線可以穿過雲層呢?
這個問題依雲層厚度而異,但是一般天氣狀況下,80%的紫外線穿過雲層是沒有問題的
Clouds don't protect you from sun damage. According to the American Academy of Dermatology, up to 80% of the sun's UV rays can pass through clouds and damage your skin. You should wear sunscreen or protective clothing even on cloudy days.
所以不要太冀望雲層可以幫你防曬
 
6.Window glass protects your skin from all harmful UV rays.車窗玻璃可以替你阻擋傷害你的紫外線?
UVB rays, which cause sunburns, can’t penetrate glass, but UVA rays can. The American Academy of Dermatology recommends that you use a broad-spectrum, water-resistant sunscreen with an SPF of at least 30 year-round, even if you’re going to be inside.
對於UVB來說,目前汽車的擋風玻璃都可以攔截下來,但是會讓你快速晒黑的UVA可能就不一定了,所以就算坐在車子裡面,還是選用廣域的防曬吧

關於防曬的指標,可以看這邊:

關於防曬的幾個指標

 
 
7.A sunscreen with an SPF of 30 provides double the protection of one with an SPF of 15?
SPF 30的防曬產品提供的防曬能力是SPF的兩倍?
當然錯:

SPF stands for "sun protection factor," and that refers to how much longer it takes you to sunburn while wearing that sunscreen, not to how much protection you're getting. For example, it should take 15 times longer for you to sunburn with an SPF 15 sunscreen than it would if you weren't wearing any; with an SPF 30, it should take 30 times longer. 

An SPF 30 screens out only a small percentage more UVB rays (96.6%) than an SPF 15 (93%), so higher SPF numbers do not indicate a proportionately higher amount of sunscreen strength. No sunscreen provides 100% protection.

以遮蔽率公式來計算:
SPF遮蔽率換算公式
[(SPF-1)/SPFx100%=遮蔽率(%)]
如SPF30 29/30x100%=96.6%
 
所以SPF 15遮蔽率為93.3%
knowledge_P01spf  
 
8.Most people use the recommended amount of sunscreen.大多數人使用到建議的防曬劑量
當然是沒有
You need about an ounce of sunscreen to properly cover the exposed areas of your body, and most people don't use enough. According to the American Academy of Dermatology, most people apply only 25% to 50% of the recommended amount of sunscreen.
SPF的原則裡面,是需要塗抹2mg/cm2的標準量,講白話文就是每平方公分要2毫克的量。容我告訴你這是怎樣的一個厚度
這是一平方公分
IMG_1829

這是2毫克

IMG_1830  
所以你應該是不會塗成這樣出門吧
 
一般人平均塗抹劑量約在0.5-1.25mg/cm2之間
knowledge_P01spf50  
所以你的防曬能力大概要打個對折或1/4
 
9.How long can you stay in the water without having to reapply a water-resistant sunscreen?
如果是防水的防曬霜,大約可以再水中維持多久呢?
A “water-resistant” label means the sunscreen works in the water for about 40 minutes. Very water-resistant sunscreens give you about 80 minutes in the water. (No sunscreen is completely waterproof.) Like all sunscreens, water-resistant products should be reapplied after two hours, regardless of water exposure, and after toweling off.
以一般防水標示的意義是在水中可以維持40分鐘的防護能力,號稱超級防水的防曬霜,要有80分鐘的防護能力,一般防曬產品大約兩個小時要補充一次,如果是毛巾擦過,就立刻補充。
簡單算一下,如果你帶著SPF50的防曬出門,你的膚質大約是10分鐘就會晒傷,這樣算起來你的防護時間大約是50x10x0.25=125(分鐘)
 
10.Some sunscreens contain a chemical that can be harmful to your health.
部分化學性防曬商品可能會傷害你的健康?

不全然正確

Some sunscreens contain a naturally occurring chemical called Benzophenone-3 (BP-3), which passes through the skin into the body. According to the CDC, scientists have discovered widespread exposure to BP-3 in Americans and “the human health effects from skin exposure to low levels of BP-3 are unknown.” However, the CDC also states, “finding a measurable amount of BP-3 in urine does not mean that levels of BP-3 cause an adverse health effect.”

The American Cancer Society “continues to support the use of sunscreen products as one of the measures to limit skin exposure to ultraviolet radiation, while encouraging continued research on the safety and efficacy of these products.”

 
11.Unprotected exposure to the sun is the best way to get Vitamin D.不要擦防曬會得到比較多的維生素D
According to the American Cancer Society, "Whenever possible, it is better to get vitamin D from your diet or vitamin supplements rather than from sun exposure because dietary sources and vitamin supplements do not increase risk for skin cancer, and are typically more reliable ways to get the amount you need." Dietary sources of vitamin D include eggs, fish, and foods fortified with vitamin D, such as milk, yogurt, and some cereals and bread. Sunscreen limits the amount of sun rays hitting your skin, so wearing sunscreen will decrease your skin's production of vitamin D.
目前美國癌症協會是建議從飲食中補充維生素D勝過於去直接曝曬太陽,因為至少比較不會增加皮膚癌的風險,確實穿衣服或是塗防曬會擋住陽光,減少些許維他命d的生成。
 
12.How many blistering sunburns does it take to double a child's lifetime risk of skin cancer?
晒傷起多少水泡表示小孩罹患皮膚癌的機會加倍?
基本上,一個就是了
One blistering sunburn doubles a child's lifetime risk of developing skin cancer. Children are at particular risk in the sun, because it's easier for them to get sunburned; it can take less than 10 minutes for an infant’s skin to burn. Children are also at higher risk because they tend to spend a lot of time outdoors and because they're unlikely to be mindful of the sun's dangers. Babies younger than six months old should be kept out of the sun or shielded by hats and protective clothing.
 
13.Which of the following provides better protection from the sun?A large beach umbrella?An SPF 15 sunscreen?
下面哪一個的防曬效果比較好?一把大海灘傘還是SPF15的防曬霜?
Large beach umbrellas provide good shade, but most provide little protection from UV rays, partly because UV rays can reflect off the sand and under the umbrella. In fact, the amount of UV radiation under an umbrella can be up to 84% of what you'd get out in the open sun. The SPF of a typical beach umbrella ranges from 3 to 10.
確實美白和避免晒傷的原則就是防曬,防曬的重點就是不要晒,但是單純以海邊活動來說,只是用一把大海灘傘,大約只能防護84%的紫外線,而SPF15的防曬霜可以防範93.3%的紫外線,看起來是防曬霜好一點,但是要記得一件很重要的事情:防曬霜是有時間性的,但是洋傘是一直在那邊的,所以最好的方式,是塗上防曬霜然後躲在洋傘下面。
 
14.Darker-skinned people don't need sunscreen.皮膚比較黑的不用防曬?
Although darker skin offers more natural protection from the sun than fair skin, groups including African-Americans, Hispanics, Asians, and Native Americans can still burn and still need to protect themselves from sun damage and skin cancer.
的確深色皮膚是可以比較不會晒傷,但是長期曝曬還是會罹患皮膚癌
 
15.Dark clothes protect you from the sun better than light-colored clothes.深色衣服比淺色衣服防曬效果好?
是的:

In general, ultraviolet rays pass through lighter-colored fabrics easier than dark-colored fabrics. Experts say you get the best protection from deep blue and black colors or bright colors, such as orange and red. Also, tightly woven fabrics offer more protection than loose weaves.  

If you can see light through the fabric when you hold it up to the light, the sun's damaging rays are passing through to your skin. Look for a UPF (UV protection factor) rating on clothing made especially for sun protection. UPF ratings work in a similar way as SPF ratings: the higher the UPF, the more protection from ultraviolet rays.

一般來說,紫外線比較容易穿過淺色的纖維,甚至有專家建議可以穿著深色,深藍色,如果要穿淺色的,建議可以穿紅色或是橘色的。當然,選用有抗UV的衣料會比較直接一點。

其實這跟反射色與吸收色有關,請參考:

看綠色為何對眼睛好?

 
16.Dark sunglasses block more of the sun's UV rays than lighter-colored sunglasses.
深色太陽眼鏡阻抗UV的能力比淺色的好?

Light-colored glasses can be just as effective as dark glasses at blocking UV light. Look for labels that say "Meets ANSI UV Requirements" or "UV absorption up to 400 nm,” which means the glasses will block 99% of UV rays, compared with about 70% for most cosmetic glasses.  

Sunglasses are an important aspect of sun safety, because the eyelid area is a frequent site of skin cancer (5% to 10% of all skin cancers) and sun exposure can contribute to cataracts, macular degeneration, sunburn of the cornea (keratitis), and several cancers of the eye.

當然不是,請參考這邊:

眼鏡抗UV實驗

那深淺的差別,其實是光線的強弱,所以深色眼鏡可以避免你的視網膜光灼傷
請參考這邊:

正確選擇太陽眼鏡

17.Which of the medications can increase your sensitivity to the sun?哪種藥物會增加你的光敏感性?
Birth control pills, naproxyn and other NSAIDs, and thiazide diuretics can increase your risk of burning. You also need to be careful if you take tricyclic antidepressants, sulfonylureas for diabetes, or tetracycline, sulfa drugs, or many other antibiotics. Ask your doctor or pharmacist if any medicines you're taking might make you more sensitive to the sun.
一般說來,避孕藥,非固醇類消炎止痛劑,thiazide利尿劑都會增加你晒傷的機率,尤其是三環抗憂鬱藥,糖尿病藥物中的sulfonylurea,四環素,磺胺藥還有其他抗生素更容易引起光過敏。
 
可以參考這邊:

可能導致色素增生的藥品

還有這邊:
 
18.Melanoma -- the most deadly form of skin cancer -- most commonly occurs on ??黑色素細胞瘤最常發生在哪邊?
Although most skin cancers occur on frequently exposed parts of the body, such as the face, ears, neck, forearms, and hands, melanoma most commonly occurs on the upper back for men and the lower legs and upper back for women. So it's important to consider all areas of your body when planning for a day in the sun.
雖然皮膚癌會出現在暴露比較多日曬的地方,像是臉部,耳朵,頸部,前臂和手部,不過黑色素細胞瘤比較多發生在男性的上背部以及女性的小腿和上背部,所以重點其實是針對你比較容易曝曬到太陽的地方加強防曬。
 

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