Know How to Use Sunscreen Properly

Every summer, sunscreen has become an essential item. However, many people think that a high SPF number is all that matters or that applying it just once is sufficient. According to statistics from the Ministry of Food and Drug Safety, 7 out of 10 Koreans do not use sunscreen correctly. In this article, we will explain the scientific principles of sunscreen and the correct way to use it in detail.

The Meaning of SPF and Its Actual Effect

The first thing you notice when choosing sunscreen is the SPF (Sun Protection Factor) number. SPF indicates the level of protection against UVB rays, and it’s easy to think that a higher number means longer protection from the sun. However, that’s not actually the case.

The actual meaning of SPF is as follows: SPF 30 blocks about 97% of UVB rays, SPF 50 blocks 98%, and SPF 50+ blocks over 99%. In other words, the difference between SPF 30 and SPF 50 is only 1-2%. Many dermatologists recommend that SPF 30 or higher is sufficient for typical outdoor activities.

According to a study by the Korean Dermatological Association in 2022, using SPF 30 sunscreen correctly at a dosage of 2mg/cm² was more effective than using SPF 50+ at an insufficient dosage (0.5mg/cm²). This shows how important 'using the right amount' is.

Generally, sunscreens are classified as follows:

  • SPF 15-29: For everyday indoor activities and mild sun exposure (blocks 93-96% of UVB)
  • SPF 30-49: For daily outings and outdoor activities (blocks 97% of UVB)
  • SPF 50+: For beach, outdoor sports, and high-altitude activities (blocks over 99% of UVB)

The Importance of UVA Protection and PA Index

There are not only UVB rays but also UVA rays. While UVB primarily causes surface burns and stimulates melanin production to darken the skin, UVA penetrates deep into the skin, leading to loss of elasticity, wrinkles, and pigmentation. UVA can penetrate through clouds and reach indoors, making consistent protection necessary throughout the year.

In Korea, the ability to block UVA is indicated by the PA index:

  • PA+: Blocks about 25-50% of UVA
  • PA++: Blocks 50-75% of UVA
  • PA+++: Blocks over 75% of UVA
  • PA++++: Blocks over 90% of UVA

PA+++ is sufficient for everyday outdoor activities, but PA++++ is recommended for prolonged outdoor activities or beach outings. According to a 2023 Consumer Agency survey, 62% of Koreans choose sunscreens with SPF 50+ and PA+++ or higher.

Correct Amount and Method of Using Sunscreen

The effectiveness of sunscreen starts with the 'correct amount' used. Many people apply too little, which results in a lower actual SPF value.

The correct amounts are as follows:

  • Face: A coin-sized amount (about 0.5ml) - this should be divided into three parts and applied.
  • Neck + Ears: Half a coin-sized amount.
  • Entire Arms: 1.5 times a coin-sized amount.
  • Entire Legs: Three times a coin-sized amount.
  • Full Body: About 35ml (for standard creams, based on a dosage of 2mg/cm² of skin surface area).

In reality, many people only use 25-50% of the recommended amount. This means that even with SPF 30, the actual effectiveness drops to the level of SPF 5-10.

Correct Application Method: First, for cream types, apply evenly over the entire face and gently pat with your fingers to absorb. For spray types, spray from a distance of 10-15cm and spread with your hands, while stick types should be rubbed evenly over the entire face.

Reapplication: The Hidden Essential Step of Sunscreen

Thinking that applying sunscreen once in the morning will last all day is a big misconception. The effectiveness of sunscreen diminishes over time due to sweat, sebum, and friction.

Recommended Reapplication Times:

  • General Outdoor Activities: Every 2-3 hours.
  • Swimming or Heavy Sweating Activities: Every hour or immediately after the activity.
  • Indoor Work: Once during lunch or around 3 PM.
  • Beach Activities: Every 30 minutes to 1 hour.

However, it can be difficult to reapply when already wearing makeup. In such cases, the following methods are recommended:

  • Cushion or Compact Powder: Choose SPF 30-50+ products for light touch-ups over foundation (around 5,000-15,000 won).
  • Sunscreen Spray: Convenient to carry and allows for quick reapplication on the face and hairline (around 10,000-20,000 won).
  • Sunscreen Mist: Can be sprayed over makeup (around 8,000-18,000 won).
  • Wipe Off and Reapply: Use a lightweight sunscreen with a texture similar to base products (around 12,000-25,000 won).

According to the 2024 Korean Beauty Trend Report, sales of reapplication sunscreen products increased by 45% compared to the previous year, with cushion and mist types gaining significant popularity.

Characteristics and Selection Guide by Product Type

Sunscreens come in various forms such as creams, essences, lotions, and sprays, each with its own advantages and disadvantages.

Cream Type (around 15,000-40,000 won): Offers high UV protection and excellent longevity. Suitable for dry skin or winter use, but may have lower spreadability and absorption. It allows for the largest amount to be used, effectively delivering the SPF value.

Essence Type (around 12,000-35,000 won): Lightweight texture and quick absorption are advantages, making it popular for oily skin or as a makeup base. However, it may require frequent reapplication due to lower longevity.

lotion Type (around 10,000-30,000 won): Commonly used for the body, it can be applied quickly over large areas. It has better moisturizing properties than essence types.

Spray Type (around 15,000-25,000 won): Convenient to carry and quick to apply, but may leave blind spots and poses inhalation risks, so caution is needed. It is the most popular for reapplication.

Stick Type (around 8,000-18,000 won): Convenient for targeted areas like around the eyes and cheekbones, with excellent portability. Its popularity has surged among professionals who travel or engage in outdoor activities.

Seasonal Sunscreen Use Strategies

UV rays are always present regardless of the season, but blocking strategies should be adjusted according to intensity.

Spring (March to May): A time when UV intensity gradually increases. Choose SPF 30-40 and PA+++ as a base, but upgrade to SPF 50 if outdoor activities increase after April.

Summer (June to August): The time when UV rays are strongest throughout the year, making SPF 50+, PA++++ essential. Reapplication every 2 hours is basic, and it’s advisable to reapply every hour during beach activities.

Fall (September to November): While UV intensity decreases, protection is still necessary. SPF 30 and PA+++ are sufficient, with reapplication every 3-4 hours.

Winter (December to February): UV rays are at 40-50% of summer levels, but caution is needed for UV reflected off snow or ice. SPF 30 and PA++ are sufficient, and reapplication once in the afternoon is adequate for indoor work.

Precautions When Choosing Sunscreen

When selecting sunscreen, do not judge solely by the SPF number. Be sure to check the following factors.

Check Ingredients: If you have sensitive skin, choose products labeled 'Noncomedogenic' to prevent pore blockage. If you don’t want a white residue, 'Powdery' or 'Fadeless' products are recommended.

Select by Skin Type: Oily skin should choose lightweight essence or lotion types, while dry skin should opt for cream types rich in moisturizing ingredients. For sensitive skin, mineral sunscreens (zinc oxide, titanium dioxide) are recommended.

Check for Waterproof: According to the Ministry of Food and Drug Safety, 'waterproof' products maintain over 80% effectiveness after being submerged in water for 40 minutes. Regular products are based on a 20-minute standard, so choose waterproof products for activities involving water and sweat.

Check Expiration Date: Sunscreen should be used within 3 years if unopened and within 1 year after opening. Over time, active ingredients may degrade.

Conclusion

Sunscreen is not just a beauty product but an essential medical item for protecting skin health. Here’s a summary of the proper way to use sunscreen:

First, understand SPF and PA values. The difference between SPF 30 and SPF 50 is only 1-2%, and SPF 30+, PA+++ is sufficient for daily activities. What matters most is the correct amount used rather than just a high number.

Second, use a sufficient amount. Apply a coin-sized amount (about 0.5ml) to the face in three parts and gently pat with your fingers to absorb. Using insufficient amounts drastically reduces the SPF value.

Third, reapply regularly. For general outdoor activities, reapply every 2-3 hours, and immediately after swimming or heavy sweating. If already wearing makeup, choose convenient products like cushion, mist, or stick types.

Fourth, choose products suitable for the season and situation. In summer, SPF 50+, PA++++ is essential, while in fall and winter, SPF 30, PA+++ is sufficient. Oily skin should opt for essence types, while dry skin should choose cream types.

The Ministry of Food and Drug Safety recommends that all adults use sunscreen daily, using higher SPF products only during prolonged outdoor activities, and that SPF 30 is sufficient for everyday use. The most important thing is 'consistent use.' If you use enough sunscreen correctly every day and reapply regularly, you can significantly reduce skin damage and maintain healthy skin for a long time.