SPF (Sun Protection Factor) — Ingredients

Category: Ingredients

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An international standard index indicating how well a sunscreen blocks UVB rays

What is SPF (Sun Protection Factor)?

An international standard index indicating how well a sunscreen blocks UVB rays

SPF 30 blocks about 97% of UVB, while SPF 50 blocks about 98%. PA indicates the UVA protection grade.

Key properties & actions

SPF (Sun Protection Factor) is an internationally standardized index that indicates how effectively a sunscreen protects the skin from UVB rays, which are the primary cause of sunburn. SPF 30 is known to block approximately 97% of UVB rays, while SPF 50 blocks approximately 98%; higher numbers do not result in a proportionally greater increase in protection. PA is a separate rating system that uses plus signs (+) to indicate the degree of protection against UVA rays, which penetrate more deeply into the skin.

How to manage

Applying a sufficient amount (approximately the size of a 500-won coin for the face) evenly 20 minutes before going outdoors is recommended. Since the protective film is removed by sweat, water, and rubbing, reapplying every two to three hours during outdoor activities is advisable. Checking both the SPF and PA ratings when selecting a product helps ensure broad-spectrum coverage against both UVB and UVA rays.

Good to know alongside

SPF is discussed alongside PA rating, UVA and UVB, mineral (physical) and chemical sunscreens, and the concept of broad-spectrum protection.

Everyday care tips

UV rays are present even on cloudy days and can penetrate through windows indoors, so applying sunscreen daily year-round and making sure to cover easily overlooked areas such as the backs of the hands, the neck, and the ears is advisable.

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Frequently Asked Questions (FAQ)

What is SPF (Sun Protection Factor)?
An international standard index indicating how well a sunscreen blocks UVB rays. SPF 30 blocks about 97% of UVB, while SPF 50 blocks about 98%. PA indicates the UVA protection grade.

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Medical Disclaimer

SKINROUTE is not a medical device or healthcare provider. All content is general skincare information for reference only. If you have concerns about your skin, please consult a board-certified dermatologist.