What is SPF and PA + / ++ / +++?
Sunscreen works to reduce the harmful effects of sunlight on the skin when in the sun, essentially reducing the effects of UVB and UVA rays. The purpose of the use is to prevent skin from burning, tanning and skin cancer. Sunscreen is measured by the sun protection factor SPF (sun protection factor) - an indicator of how long the skin can be protected and the PA + / ++ / +++ index, which is stated on each product. What does that indicator mean? We have to understand how is right?
Different types of sunscreens will have different SPF numbers. The lowest SPF in sunscreen is usually 15. In principle, the SPF 30 filters 95% of UV rays and the index above 50 filters 97% (only more than 2%).
Therefore, we often make the mistake of thinking that a high SPF will protect the skin better without knowing that the skin is hurt when using the wrong index. In fact, the higher the SPF, the greater the ability to protect the skin in the sun for longer, not better than the low index. Sunscreens with SPF 20 - 30 are indicated for light skin and SPF below 20 for dark skin.
The most commonly used type is the SPF 30 -50. Very high SPFs (60-100) should only be used on special areas of the skin, such as those on melasma or sun allergies. Many people choose to use a sunscreen with a very high SPF (on the market there is a sunscreen with SPF 81), which means that the time to protect the skin from the sun lasts longer.
However, because the greater the SPF, the cream stays on the skin for too long, it will combine with the secretion of the skin, sweat fluid creates chemical reactions, producing free radicals that cause skin damage and turn color. Meanwhile, the phenomenon of tortoise, freckles will increase.
According to international norms, 1 SPF has the ability to protect the skin, limiting the harmful effects of UV rays in about 10-15 minutes, depending on the time of strong or weak UV exposure and skin characteristics of each person. However, this effect is not stable due to dirt, sweat, clothes and water as well as the use of sunscreen.
Therefore, the actual time to protect skin from UV rays is only 50-60% of the theoretical time. Thus, if you use a sunscreen with an SPF of 30, the skin's ability to be protected is about 200 minutes. Moreover, for optimum effect, it is necessary to apply sunscreen 30 minutes before sun exposure to make it work or you can use sunscreen as a foundation when applying makeup.
PA Index: abbreviated by PFA (Protection Factor of UVA) is an indicator of sunscreen's ability to protect skin from UVA rays. In fact, most sunscreens are capable of filtering UVB rays so few products can protect the skin from the harmful effects of UVA rays. Therefore, the new cosmetic manufacturers give the PA index according to the corresponding levels:
- PA +: Effective against UVA (Level 40-50%)
- PA ++: Very effective against UVA (Level 60-70%)
- PA +++: Highest UVA protection (90% or higher, maximum 98%)
It is advisable to apply the cream to the arm before applying to other areas.
Note when using sunscreen
Everyone should use sunscreen at an early age to protect their skin. People with thin, light-colored skin that easily catches the sun must necessarily use sunscreen when outdoors. People with skin conditions such as: photosensitive skin disease, systemic lupus erythematosus, colloidal disease ., patients taking light-sensitive drugs (doxycyclin, tetracycline .) are Sunscreen should be used regularly for protection.
In order for the sunscreen to promote its real protection effect, it is first necessary to choose a sunscreen with SPF that suits your skin color and the purpose of use (for daily use or when working outdoors, bathing .).
For each skin color, each person can choose a suitable sunscreen. For those with normal skin color and not much sun exposure, you can use products with SPF below 30. People who often have to go to the sun should choose sunscreen with an average index of about 30-50. for daily use.
But when bathing outside the beach, you can use the type with sun protection index higher than 50 (50 +). Whites are less pigmented because of the small amount of pigment in their skin, so sunscreen should be used with a higher index than yellow skin and black skin.
It is not necessary to apply too much sunscreen, just a thin layer of cream. If applied too thick, the excess cream does not penetrate into the skin will cause skin allergies in the summer. When using sunscreen for bathing, after soaking in seawater for about 50 minutes, it is recommended to clean, dry the body and reapply a new layer of cream to protect the skin.
Avoid sunscreen on the mucosa because some sunscreens can cause irritation if sticking to the mucous areas such as eyes, mouth .
Do not use sunscreen in combination with other topical medications. Sometimes, when these drugs are combined, it can cause drug interactions that affect the skin, even cause skin irritation and irritation.
Note: Before applying sunscreen, it is advisable to try a little cream on the skin about 1cm2 in the area in the arm for 3-4 days if there are no signs, you can be assured to spread on the entire face. When applying the test but showing abnormal signs, stop immediately and search for other creams.
Possible reactions when using sunscreen
Skin irritation: After applying red, thick, tight, burning skin cream and feel uncomfortable.
Allergies: Because the skin cannot tolerate certain ingredients in sunscreen: redness, edema, itching. In more severe cases, there may be dense, watery blisters.
If you see any of the above signs, you must stop using sunscreen, and immediately see a dermatologist.