Title: SPF and PA. Do You KNOW your sunscreen?
From: Beautyficient
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Sunburn
When exposed to the sun,
our bare skin will eventually get
red, swollen and feel painful because
the internal structures are damaged.
This is commonly known as sunburn.
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UV
The main culprit?
Ultra Violet rays or UV rays from the sun.
UV rays can be further split into
UVA, UVB and UVC rays
which all cannot be detected by
the naked eye.
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UVA
The Ageing ray and
main reason behind sun related skin cancers.
It destroys the vitamin A in our skin and
also indirectly causes DNA damage.
Makes up 98.7% in UV rays.
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UVB
The Sunburn ray.
This ray directly causes
DNA damage to skin cells.
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UVC
The most powerful out of all three rays,
but most often filtered so
there’s almost none of it when
it reaches our skin.
Damages DNA directly too.
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All three rays
UVA, UVB and UVC damages the
collagen fibers in our skin which is
responsible for keeping our skin young,
as collagen contributes to the
elasticity of our skin.
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So, it is reasonably clear that
UV rays contribute significantly to
accelerate ageing of our skin as well as
any part of the body exposed to it,
such as our eyes.
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SPF
Stands for Sun Protection Factor.
It is a way of expressing
how effective a sunscreen is at
protecting against UVB rays specifically.
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The numerical digit following SPF indicates
how much time you’ll be able to
withstand exposure to the sun before
burning up in sunburn frenzy.
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For an example,
If Brad Pitt took 15 minutes to reach
the state of being sun burnt,
an SPF30 sunscreen will delay his time to
achieve a sunburn by 30 times more.
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A higher SPF will of course give
better protection against UVB, but usually,
SPF 30 would be sufficient for daily use.
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For folks with lighter skin,
a higher SPF such as SPF 50 would be
more effective as they burn much faster
compared to people with darker skin.
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PA
Abbreviation for Protection Grade of UVA
established by the Japanese.
It basically informs users of
the level of protection towards UVA rays.
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PA+
means the sunscreen provides
some protection against UVA rays,
PA++
indicates moderate protection while
PA+++
shows very good protective abilities
against UVA rays.
Since UVA causes long term skin damage,
it is therefore advisable to go for
sunscreens with the highest PA rating.
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Broad Spectrum
Sunscreens that provide both
UVB and UVA protection
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Sunblock vs sunscreen
Sunblock provides better protection from
UV rays compared to sunscreen as
they contain a more opaque formulation,
hence, require less bouts of reapplying.
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The chemicals in sunscreens breakdown at
a faster rate under sun exposure so
are comparatively,
a little less effective than sunblocks.
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Apart from that,
sunscreens are better suited for daily use while
sunblocks are best for sports or activities
requiring higher exposure to UV rays.
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Typically, sunscreens today are made to
suite the conditions of the wearer’s skin.
Sunscreens come in moisturizing, mattifying,
make up base, color correcting,
plumping, anti ageing, fragrance free and
many more varieties of formulations.
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In short
Also, the sunscreen should be
a broad spectrum formula with
an adequate SPF and
the highest PA rating possible.
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As a guideline,
SPF 30 PA+++ for daily wear,
SPF50 PA+++ for outdoor activities or
for folks living nearer to the equator.
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Title: Chemical Vs. Physical Sunscreens: Pros And Cons
From: Renee Rouleau
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Physical sunscreens
contain active mineral ingredients,
such as titanium dioxide or zinc oxide,
which work by sitting on top of the skin to
deflect and scatter damaging UV rays
away from the skin.
They are often referred to as physical blockers.
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Pros of physical sunscreens
Offers protection against both
UVA and UVB rays and
is naturally broad spectrum
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Protects from the sun as soon as it’s applied
no wait needed
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Lasts longer when in direct UV light
(but NOT when doing physical activities
that cause the skin to get wet or sweat)
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Less likely to cause
a stinging irritation on the skin,
making it better for sensitive skin
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Better for those with heat-activated skin
(like those with rosacea and redness) since
it deflects the heat and energy
given off by the sun away from the skin
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Less likely to be pore-clogging,
making it ideal for blemish-prone skin types
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Longer shelf life
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Cons of physical sunscreens
Can rub off, sweat off and rinse off easily,
meaning more frequent reapplication
when outdoors is needed
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May leave a white-ish cast on the skin,
making some formulas incompatible for
medium to dark skin tones
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May be too chalky and opaque for
daily use under makeup
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Can create an occlusive film,
which results in increased perspiration
during physical activities and, therefore,
causes it to wear off more quickly
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Can be thicker,
which will require more effort to rub in
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Can cause white drips to
show on the skin when sweating
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Can be less protective if
not applied generously and accurately
since UV light can get between
the sunscreen molecules and
get into the skin
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Chemical sunscreens
contain organic (carbon-based) compounds,
such as oxybenzone, octinoxate,
octisalate and avobenzone,
which create a chemical reaction and
work by changing UV rays into heat,
then releasing that heat from the skin.
They are often referred to as
chemical or organic absorbers.
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Pros of chemical sunscreens
Tends to be thinner and, therefore,
spreads more easily on the skin,
making it more wearable for daily use
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Less is needed to protect the skin because
there is no risk of no spaces between
the sunscreen molecules after application
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Formula is easier to
add additional treatment ingredients,
such as peptides and enzymes,
which offer other skin benefits
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Cons of chemical sunscreens
Can possibly cause an increase in
existing brown spots and discoloration
due to a higher internal skin temperature
(Yes, over-heated skin can make
brown spots worse. Read why here.)
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Requires about 20 minutes
after application before it begins to work
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Increased chance of irritation and stinging
(especially for those who have dry skin with
a damaged moisture barrier)
due to the multiple ingredients combined
in order to achieve broad spectrum
UVA and UVB protection
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The higher the SPF
(such as formulas of SPF 50 or greater),
the higher the risk of irritation for
sensitive skin types
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The protection it offers gets used up
more quickly when in direct UV light,
so reapplication must be more frequent
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Increased chance of redness for
rosacea-prone skin types because
it changes UV rays into heat
which can exacerbate flushing
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May clog the pores for oily skin types
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Can cause stinging if
it drips into the eyes from sweat
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When it comes to sunscreen,
it’s hard to say which one is
truly the best for your skin
since all formulas are not created equal.
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Which type of sunscreen offers
the best UVA and UVB protection?
This is a huge debate among scientists.
Currently, the FDA is taking steps to
establish new standards of measuring
the effectiveness of sunscreens more accurately
in an effort to educate consumers on
how best to prevent the detrimental effects of
exposure to UV radiation.
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For now, however,
both physical and chemical sunscreens
will do a great job at protecting your skin,
as long as you are applying them
generously every morning and
reapplying throughout the day.
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Title: 夏日防曬論 豈止讀懂 UVA、UVB 那麽簡單
From: Harper Bazaar HK
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新商品法例禁誇大
由去年起，"Water Proof" 或 "Sunblock" 等字眼
已消失於美國出品的防曬產品。
皆因去年一月，美國 FDA（美國食品及藥物管理局）
對防曬產品作出新規定：
防曬產品只可標籤為 "Water Resistant"，
不能再用 "Water Proof"，
因為經測試證實沒可能 100% 防水，
且 "Water Resistant" 時間
只許標示為 40 或 80 分鐘，
因為防曬時間根本無法超過 80 分鐘；
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產品需同時抵擋 UVA 及 UVB，
才可歸類為防曬產品（Broad Spectrum 類別）；
防曬產品也不能標籤為 "Sunblock"，
因為沒可能 100% 阻隔紫外線，
只可稱為 "Sunscreen"；
須蘊含防紫外線（UV）成分的產品才
可歸類為 "Anti-aging"，
簡單而言就是要產品之名如實。
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雖然這些老實標籤只限
美國出品的防曬產品，
但對女性而言，總算多個誠實選擇渠道。
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外國有新例規管防曬產品的標籤，香港亦然，
《2012 年商品說明（不良營商手法）（修訂）條例》
於 2013 年 7 月 19 日日正式生效，
限制商品說明都不能有
誤導性遺漏、餌誘式廣告宣傳等。
那些年有令人無法抗拒的魔力字眼：
「最防曬」、「最受歡迎」及「最暢銷」，
統統說再見，防曬產品同時也告別
絕對百分百防曬等用語。
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不過對於產品的標籤，
則沒進一步限制規管，
所以相對消費者而言，分別不大。
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系數強弱按需要
防曬產品必定列有 SPF 及 PA 值，
探究兩者意義前，
先要明白紫外線分為
UVA、UVB 及 UVC 三種，
大部分 UVC 會被臭氧層阻隔，
只餘 UVA 和 UVB 投射地面，影響皮膚，
前者可直達真皮層，破壞細胞，
長年累月造成肌膚老化鬆弛、
皺紋及黑色素沉澱；
UVB 的能量比 UVA 強，導致即時性傷害，
如暗沉、變紅、眼膜炎及皮膚發痛變乾，
防曬產品的任務就是阻隔 UVA 和 UVB。
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SPF（Sun Protection Factor）
是由美國醫生指定的防曬指標，
用來衡量會曬傷肌膚的 UVB 防曬度，
如防曬度數 SPF15、30 跟 50
分別可阻隔約 94%、97% 及 98% 的紫外光；
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PA（Protection Factor of UVA）
則是對 UVA 的防護能力，
PA 值可分為
PA+、PA++、PA+++、PA++++ 四種，
+ 號愈多，代表對紫外線 UVA 的防護力愈高，
簡化點就是延緩皮膚曬黑的指數，
例如 PA+ 可延緩皮膚曬黑 2 至 4 倍、
PA++ 是 4 至 8 倍，
PA+++ 則可達 8 倍以上。
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選購防曬產品並非
追求越高數值、越多加號為好，
因為防曬系數越高，
代表所含的化學物相對的多，
隨時未阻隔陽光，先刺激肌膚。
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一般戶活動，
建議選擇 SPF15，PA+ 的防曬已足夠；
若同陽光玩遊戲，
就要選擇 SPF35 以上、PA++ 或以上的防曬產品，
並謹記在流汗後補塗。
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想防曬產品功效發揮最好，
就要在出門前最少半小時前塗搽，
而防曬系數亦非一般加數，
縱然現今底霜、粉底都具防曬功能，
但防曬系數並不能累積計算，
譬如使用了 SPF15 的防曬面霜，
再用 SPF30的防曬乳，
只相等於塗上 SPF30 的防曬。
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物理性防曬最安全
防曬產品可以分出無限多類別，
乳液狀、噴霧裝，
甚至具調色等多功能性，
但最基本且必須要知的，
就是為分化學性及物理性。
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化學性原理是 (Chemical)
經皮膚吸收化學物質來抵禦紫外線，
優點為淸爽不稠，
但較容易引起過敏，皮膚易敏感者慎用；
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物理性則是 (Physical)
在皮膚上形成一反射性層，
把紫外光反射，猶如為皮膚穿上防曬保護衣，
阻隔、折射、及散射紫外光，
大部分的物理性防曬產品都是
採用天然礦物提取成分，
如氧化鋅（Zinc Oxide）及
二氧化鈦（Titanium Dioxide），
加上不被皮膚吸收，不易引發皮膚敏感，
適合敏感性皮膚人士和肌膚較嫩的兒童使用。
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但由於二氧化鈦和氧化鋅是礦物粉體，
須與植物或礦物油、水等成分配合，
才能製出乳霜，
故物理性防曬的質感都較化學性油膩，
且謹記要以卸妝產品徹式清除。
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