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Basic Skincare : Sunscreen (English Ver.)

June 15, 2020





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



 Note : This is the English version of my last year sunscreen guide post. For Bahasa Indonesia version, click here >> Basic Skincare : Sunscreen



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