Sunlight is electromagnetic wave emitted by the sun which are infrared (IR), visible light, and ultraviolet (UV). UV is invisible light which brings strong energy, it has 3 different types that are UVA (the weakest yet the longest wavelength), UVB, and UVC (the strongest yet the shortest wavelength). UVC has the strongest energy and the most damaging for the Earth, but it has been absorbed by ozone in the stratosphere before reaching the Earth surface. While most of UVB gets absorbed by ozone, the rest can reach the Earth which is less than 1%, yet this has stronger energy than UVA.
UVA
Even though UVA and UVB have different wavelength,
they both have damaging effect on human skin. UVA can go through skin dermis
layer, causing tanning, DNA damage (lead to skin cancer) and photoaging. UVA
which is 95% of overall UV radiation that reaches Earth surface is not as
strong as UVB to directly damage DNA, yet it can trigger the oxygen radical
forming and cause the DNA oxidation. Based on study by NYU School of Medicine,
UVA can damage melanocytes, causing DNA mutation and forming melanoma.
Melanocytes produce melanine to protect skin from UV radiation by producing
dark pigment on skin. In severe condition, melanocytes can be easily damaged
since they can’t repair themselves (compared to other cells in human body).
UVB
UVB only reaches epidermis (the outer layer of skin)
causing burning and DNA damage. Even though it doesn’t reach the dermis, UVB
which is 1% of overall UV radiation that reaches Earth can change DNA chain
structure. UVB forms dimer that can change DNA structure from its original
form, so the cells can’t work normally as it is. Each cell exposed by UVB can
form up to 100 dimers. When there are too many dimers in a cell, then a cell
will either die (because of dimer accumulation) or turn into a cancerous cell
that grows uncontrollably.
Both UVA and UVB has the ability to form Squamous
Cell Carcinoma (SCC) and Basal Cell Carcinoma (BCC) which are the two most
commonly found skin cancers on human.
UV Index
Based on FDA (Food and Drug Administration), the
amount of UV radiation expose to human can vary depending on : geography,
altitude, weather, time and reflection. The highest UV radiation is equator and
places with snow, pavement, sand and water. We are suggested to wear sunscreen
when UV Index reaches 3 (for easily burned skin or sensitive skin, it’s
important to wear sunscreen even though UV Index points at 1) around 10 AM – 4
PM whether sunny or cloudy, since UVA can go through the mirror and cloud.
UV Index (Ultraviolet Index) first was introduced in
Canada on 1992, then developed on 1994 by National Weather Service (NWS) and US
Environmental Protection Agency (EPA) for outdoor activities planning and
reducing excess amount of UV radiation related to health.
Categories :
1-2 :
LOW
3-5 :
MODERATE
6-7 :
HIGH
8-10 :
VERY HIGH
11+ :
EXTREME
How can we protect skin from UVA and UVB?
By wearing broadspectrum sunscreen or sunscreen that
mentions SPF and PPD/UVAPF/PA on its packaging. Sunscreen is substance applied
on skin to shield it from UV radiation that causes skin aging (wrinkle and dark
spots) and DNA damage (lead to skin cancer). Beside, sunscreen is the best
skincare we can use to prevent any other existed skin problems from being
worse, such as acne and acne scars.
SPF (Sun Protection Factor)
SPF (Sun Protection Factor) is the ability of a
sunscreen to protect skin from UVB (burning). If our skin normally will get
burnt after 15 minutes under the sunlight, then SPF 50 (with the proper amount
usage) means 15 x 50 = 750 minutes. It can “delay the burning” up to 750
minutes. So, can we stay under the sun for 750 minutes? Nope. SPF only protects
you from UVB. You have to still deal with UVA, baby.
UVB protection percentage :
SPF 15 gives 93% protection, means there are still 7%
foton going through our skin.
SPF 30 gives 97% protection, means there are still 3%
foton going through our skin.
Based on Cosmetic Chemistry, a book by Ayaz Mahmood
Dar, sunscreen with higher SPF such as SPF 75 can’t give you 100% protection,
meaning there are still some percentage of foton going through your skin. So,
it can be said, SPF prevents or delays the sunburn and minimalizes UVB that
goes through our skin.
PA (Protection Grade of UVA)
PA firstly introduced in Japan, adapted from PPD
(Persistent Pigment Darkening) where in this method UVA that causes darkening
or tanning is used. In this test, sunscreen with PPD 10 can protect the skin
from UVA 10x stronger than without sunscreen.
PPD 2-4 :
PA+ (some protection)
PPD 4-8 :
PA++ (moderate
protection)
PPD 8-16 :
PA+++ (high
protection)
PPD >16 :
PA++++ (extremely high
protection)
Unfortunately, PA only uses + for its symbol, so PPD
17 or 20 will be both labeled as PA++++ as the highest level of this method.
UVAPF (Ultraviolet A Protection Factor)
UVAPF (Ultraviolet A Protection Factor) is actually
another form of SPF that is used for UVA protection. It’s previously used in
Europe. Colipa UVA Method is used by counting the amount of UVA energy that can
go through sunscreen layer applied on plastic, not human skin.
Broad Spectrum
US or Canada products usually are labelled as “Broad
Spectrum” that point out a product for its ability to protect our skin from UVA
and UVB. 90% of total UV absorbed by a sunscreen product should be less than
370 nanometer, then a product can get this label. But, this method is said to
be ineffective since all the sunscreen products that has weaker UVA protection
can be sorted into this category.
Which sunscreen should we choose?
Anything. Product that is comfortable to use
everyday. Please remember that, you can’t only see for how much SPF of a
product has (that is actually UVB protection) but also the PPD/UVAPF/PA that
protects our skin from UVA.
Inorganic Sunscreen
Inorganic sunscreen or physical sunscreen or mineral
sunscreen is a type of sunscreen which doesn’t have carbon compound in its UV
filters, which are Zinc Oxide and Titanium Dioxide.
Organic Sunscreen
Organic sunscreen or chemical sunscreen is a type of
sunscreen which has carbon compound in its UV filters, such as Avobenzone,
Homosalate, Octinoxate, Tinosorb S, Tinosorb M, Uvinul A, etc. Or anything that
is not Zinc Oxide nor Titanium Dioxide.
Chemical and physical sunscreen namings are actually
inappropriate, since physical sunscreen is also consist of the chemicals
(anything in this world is chemical), and chemical sunscreen is actually
forming a physical layer to protect the skin. Since they have been named like
that, you can call them with any names you like.
Both inorganic and organic sunscreen works by
absorbing UV. Inorganic filters absorb some and reflect the rest. While the
organic filters absorb and turn the UV into heat and inactivate it. The newer
organic filters like Tinosorb M has the ability to reflect some of UV like
inorganic filters do.
Sunscreen categories based on its consistency :
1. Cream
2. Lotion / milk
3. Gel
4. Stick
5. Spray
6. Powder
Choosing sunscreen based on skin types :
Sensitive skin :
1. Avoid products with PABA (p-Aminobenzoic Acid), Benzophenone,
fragrance and oil
2. Find the label : hypoallergenic, for sensitive
skin, soothing, mild, etc
3. the safest choice will be inorganic or mineral
sunscreen with only Zinc Oxide and Titanium Dioxide in it.
4. Choose a product with soothing ingredient such as
Aloe Vera
Oily Skin :
1. Choose : gel or water based products
2. Avoid products with oils and fragrance
3. Find the label : for oily skin, non-comedogenic
Dry Skin :
1. Choose : cream consistency or products with
moisturizing feature
2. It usually has : glycerin, hyaluronic acid, etc
3. Find the label : for dry skin, moisturizing, etc
Usage Suggestion :
1. Wear 15-20 before going out whether it’s sunny or
cloudy
2. Re-apply after every 2-3 hours for general
activities / outdoor, or every 40 minutes for activities with includes water
contact, such as swimming. Read the labels for maximum protection.
3. If you need to, apply your acne spot treatment 20
minutes before wearing sunscreen.
4. Proper amount for sunscreen usage (to get maximum
protection as its label) is 1 mg/cm2 or around ¼ teaspoon for the whole face.
If you wear the sunscreen below the proper amount, you ca’t get the maximum
protection as mentioned in the label. For example, when you apply sunscreen
with SPF 30 in half of suggested amount, you may only get SPF 5.5 protection.
My Favorite Sunscreen Products :
Skin type : oily skin
Skin condition : dehydrated skin
Disclaimer : not sponsored
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