Ultra Violet rays
There are 2 basic types of ultra violet (UV) rays in the sunlight that are hitting the earth; UVA and UVB rays. Both play a role in the formation of skin cancer. Approx. 95% of the sun light hitting the earth are UVA rays. UVA rays are not filtered by clouds nor absorbed by the ozone layer like UVB rays. UVA rays can penetrate windows and clouds! Even though UVB rays make out only 5 %, they are much more intense than UVA rays.
UVA (A = aging)
UVA penetrate deeper into the skin than UVB rays, causing long-term skin damage and playing a greater role in premature skin aging (i.e. the formation of wrinkles).
UVA also causes more genetic damage than UVB in skin cells where most skin cancers arise. Genetic damage can result in the formation of cancerous cells in the body. With UVA rays you don’t feel them affecting your skin, as with UVB rays you get sun burned. However, UVA rays can still make damage to your skin DNA.
UVB (B = burning)
These are the rays that gives you sunburn. UVB rays damage the outermost layers of the skin. UVB rays cause skin cancers, especially melanoma.
Whereas UVA penetrates the skin, UVB causes damage in the protective outer layers of the skin, resulting in sunburns or sun poisoning. Sunburns and tans are the result of the skin’s cellular DNA’s attempt to trying to protect itself from further DNA damage. This damage can increase the chance of developing melanoma or other skin cancers.
PA vs. SPF
PA (measures UVA)
Protection Grade of UVA (PA) is a rating system developed in Japan to represent how much UVA protection the product offers.
While UVA causes aging and wrinkles, it is relevant to know how well the product protects you against these rays.
This is what each PA rating means:
- PA+ = Some UVA protection.
- PA++ = Moderate UVA protection.
- PA+++ = High UVA protection.
- PA++++ = Extremely High UVA protection.
SPF (measures UVB)
Sun Protection Factor (SPF) is a measurement of how long you can stay outside during the day and be protected from the sun’s burn-causing UVB rays.
SPF is a measure of the sunscreen’s ability to protect your skin from UVB rays. The basic calculation works like this: “If it takes 1 minute for your unprotected skin to start turning red [in the sun], using an SPF 15 sunscreen theoretically prevents reddening 15 times longer.”
Say you purchase an SPF 30 sunscreen. If it typically takes 10 minutes until your skin starts to burn, by using the SPF 30, you’re theoretically protected from the sun for 300 minutes, or 5 hours.
Most of the K-beauty sunscreens have SPF50, which theoretically protects your skin from the sun for approx. 500 minutes, or 8 hours. Keep in mind that SPF only measures UVB!
Keep in mind that this measurement require that the sunscreen with a layer, so don’t forget to re-apply sunscreen every 2 hours.
Don’t forget your neck and top of your ears!
SPF 30 vs 50
SPF 30 blocks 97% of UVB rays and SPF 50 blocks 98% of UVB rays. So, the difference between 30 and 50 is about 1 percent.
Physical vs. chemical sunscreen
A physical sunscreen (sometimes called mineral sunscreen) uses minerals such as zinc oxide or titanium dioxide to deflect UV rays away from the skin. These formulations literally sit on the skin and block or scatter UV radiation before it can penetrate the skin.
Benefits of using a physical sunscreen:
- Blocks both UVA and UVB rays (all physical sunscreens are broad spectrum)
- Works as soon as it’s applied to the skin
- Unlikely to irritate the skin, great for sensitive skin types
- Unlikely to clog skin pores as it does not deeply penetrate the skin
- Can limit rosacea and redness as it deflects heat from the skin
Cons to physical sunscreen:
- Can be rubbed off more easily than chemical sunscreen, especially when it comes in contact with water or sweat (requiring reapplication)
- Often leaves white streaks on the skin that require more effort to fully rub in
- Pores can appear as white spots when sweating
- Not ideal for use under makeup
Benefits of chemical sunscreens:
- A thinner formulation makes application easier
- Does not cause significant streaking or white spots
- Smaller amounts are needed to cover large areas of the skin (spreads easily)
- Often found contain other skin care ingredients like peptides and growth factors which can provide added benefits
- Is more resistant to sweat or water compared to a physical sunscreen
Cons of using chemical sunscreens:
- They only start to be effective 20 minutes after application to the skin
- More likely to irritate the skin (with higher SPF formulations often being more irritating)
- Protection levels begin to drop when in direct UV light (requiring more frequent reapplication)
- Increases the change of redness in rosacea-prone skin types
- Can clog the pores, and thus exacerbate acne
- Some states, including Hawaii, are beginning to ban chemical sunscreen use as they are not “reef safe” and can damage the oceanic ecosystem.
My personal preferences
What do I personally prefer? Well, it depends on the occasion and which products I have at home. I always finish up my products before I open new ones. For work, I work in an office and stay indoors most of the time, I like to use the chemical or mixed chemical and physical sunscreen (e.g. Cosrx Aloe Soothing Sun Cream). I find those sunscreens lighter and it adds moisture to my skin and this one is so comfortable like any moisturizer without the sticky feeling.
If I know I’m going to be outside a lot and be active (jogging, walking, at sea, going to the beach etc.) and the sun is strong, then I prefer to use the physical sunscreens as they blocks the UV rays more efficiently and it gives effect immediately. With chemical sunscreen you need to put it on 20 minutes before, since it starts to be effective after 20 minutes.
It is also really important to re-apply sunscreen frequently, this is something I’m really bad at. I put on a generous amount of sunscreen as well since I have some acne scars. Wearing sunscreen will help prevent the occurrence or darkening of acne scars, so that is a must for me!
As most dermatologists are saying “The best sunscreen is the one that are being used”. So far I have found Korean sunscreens the most comfortable to wear, the other ones I have tried have just been to sticky!
By Annie Song