How Long Does Sunscreen Last?
We all know it’s important to wear sunscreen. After all, too much sun can lead to premature aging and skin damage. It can also increase your risk of skin cancer.1 But what’s the best sunscreen to wear? How often should you reapply? And how do you apply sunscreen correctly? We’ve got the answers.
What type of sunscreen should you use?
To understand what sunscreen you should use, let’s look at what you need to protect yourself from. There are two types of sun rays - UVA and UVB.
UVA rays penetrate deeper layers of your skin. They can contribute to skin cancer, premature wrinkles, and aging of your skin.
UVB rays also contribute to skin cancer, as well as damaging the top layers of your skin, and causing sunburn.
It’s important to wear sunscreen if you're outside, even when it’s cloudy. UVB rays get stronger during the day and pose the biggest risk from late morning to mid-afternoon, whereas UVA rays maintain the same level of strength throughout daylight hours and all year round, even penetrating windows and clouds.
When picking a sunscreen you should choose a broad-spectrum sunscreen. These protect against both UVA and UVB rays.
誘發濕疹復發的成因及預防方法
濕疹沒有一刀切的解決方法。嬰兒濕疹通常會在臉頰出現症狀，而成年人則傾向於其他部位出現濕疹症狀，如手肘、膝蓋背面和頸部。但無論任何年齡，濕疹爆發都可能由多種因素引起，包括遺傳和環境因素。
了解自己的濕疹成因非常重要，因為您可以改變一些生活方式來控制您濕疹症狀的嚴重程度，並減少濕疹復發的機會。
讓我們認識一些常見誘發濕疹的原因，以及如何避免這些原因令濕疹發作：
Chemical sunscreens contain ingredients that act as UV light blockers. They’re absorbed into the skin to help prevent sun damage.
Mineral sunscreens sit on the surface of the skin, acting as a physical barrier to block harmful UV rays.
Cetaphil Sheer Mineral Sunscreens provide broad-spectrum protection and include antioxidants, which can help protect your skin from surface free radicals - unstable molecules which in high quantities can contribute to aging, inflammation, and disease.
As mineral sunscreens don’t need to be absorbed into your skin they can be applied as the final step in your skincare routine, after a moisturizer.
Cetaphil also has moisturizers that include chemical sunscreen, such as Cetaphil Daily Facial Moisturizer SPF 50, which is fragrance-free and contains vitamin E. If using a moisturizer with built-in SPF there is no need to add additional sunscreen after applying and this moisturizer can be applied before your make-up.
Higher SPF sunscreens are better at blocking harmful UV rays. SPF stands for Sun Protection Factor, and it measures how much UVB radiation is required to burn protected skin, compared to the amount required to burn unprotected skin. A sunscreen with SPF 15 blocks out 93% of UVB rays, SPF 30 blocks 97%, and SPF 50 blocks 98%.
Broad-spectrum sunscreens also block out UVA rays. Two mineral ingredients included in sunscreens offer both UVA and UVB protection - these are zinc oxide and titanium dioxide. Cetaphil Sheer Mineral Sunscreens include one or both of these protective ingredients.
The best SPF for you will depend on your level of sun exposure. Dermatologists recommend that you use broad-spectrum sunscreens that are at least SPF 30,3 so it’s important you pick a sunscreen such as Cetaphil Sheer Mineral Sunscreen Broad Spectrum SPF 30* to meet these requirements. However, if you’re often out in the midday sun your risk of sunburn is higher than early morning or late afternoon, so a higher SPF will provide better protection if applied and reapplied correctly.
You should also use more caution when you’re near water, snow, or sand because they reflect the sun’s rays, which increases your chance of getting sunburn.
Your face, especially in delicate areas under your eyes, is more sensitive than other parts of your body and may require a sunscreen designed for sensitive skin.
Sunscreens for the face are often a lighter consistency with a matte finish, so they can be worn under makeup, like Cetaphil Sheer Mineral Sunscreen Face Liquid Broad-Spectrum SPF 50*.
對於控制濕疹，選擇合適的衣物相當重要。羊毛、尼龍和聚酯纖維等都是最常令濕疹復發的布料，而人造皮毛、皮革、蕾絲、天鵝絨、薄紗，甚至牛仔布，亦會導致濕疹發作或刺激肌膚，令皮膚出現痕癢。
因此，選擇穿著由棉、絲綢和竹等天然布料所製成的透氣鬆身衣服，有助減少濕疹發作。
如何清洗衣服也很重要。應避免使用含有染料和香料的洗衣產品，應選擇低敏且專為敏感肌膚而設的產品。
鎳是誘發接觸性皮膚炎的最大因素之一，因此應避免佩戴含有大量鎳的手錶、戒指或項鍊等首飾，尤其當流汗時，會令情況變得更嚴重。當汗水、唾液和其他體液侵蝕金屬物品時，會釋放出鎳離子，鎳離子容易刺激皮膚，並誘發濕疹發作。
某些食物可能會導致濕疹發作，對嬰兒和小童更為明顯，但飲食對任何人都可產生影響。
鎳含量高的食物亦可能是誘因，當中包括燕麥、豆類、扁豆、加工肉類、巧克力、堅果、種子、紅茶和罐頭食品。其他最常見會誘發濕疹，和令濕疹情況加劇的食物有雞蛋、牛奶、魚和花生。
眾所周知，壓力會對我們的肌膚造成嚴重的負面影響，患有濕疹的人也深知這一點。當我們焦慮或不知所措時，體內會釋放腎上腺素和皮質醇等荷爾蒙，而導致皮膚發炎。因此照顧好身心健康，對預防濕疹發作尤其重要。
如果您有壓力，請嘗試以下一種或多種方法來避免濕疹發作：深呼吸、瑜伽、冥想、培養嗜好或在大自然中散步。嘗試在睡前泡個溫水浴，然後塗抹具保濕和滋潤效能的產品來滋潤皮膚，以免出現痕癢。
對於某些女性來說，月經前和懷孕期間濕疹發作是極為常見。服用某些荷爾蒙藥物，例如口服避孕藥或荷爾蒙調節劑，也可能導致濕疹爆發。
更年期也會令皮膚帶來一些明顯的改變。當 50 歲左右，女性皮膚的pH值會有所改變，從而令皮膚變得更加敏感，更容易受到刺激。這些荷爾蒙的改變也意味著較年長的女性更容易出現皮疹，因而令自身的濕疹出現惡化跡象。
Bottom Line
Applying sunscreen is crucial for keeping you and your skin safe and healthy. Always make sure you’re applying enough in the first place and then reapply every two hours. Remember that harmful UVA and UVB rays are always there, even in the winter, so make sunscreen a part of your daily skincare routine, come rain or shine.
*Products only available in the US.
