How do you choose a sunscreen? What is SPF and what should it be? These are among the most common questions asked by anyone who wants to protect their skin. Sun exposure is not limited to the summer months; it is a year-round factor that accelerates skin aging and contributes to various skin concerns. Therefore, choosing the right sunscreen is one of the most effective ways to protect the skin against both visible and invisible damage.
In this article, I explain how sunscreens work, what SPF means, how to interpret the numbers, and the criteria to consider when choosing the right product—within a scientific and informational framework.
What Is SPF and What Does It Measure?
SPF stands for Sun Protection Factor and indicates the level of protection against UVB radiation.
UVB rays:
Cause redness and sunburn,
Damage the epidermis,
Contribute to photoaging.
For example, SPF 30 can extend the redness–formation time by approximately 30 times.
This does not mean complete protection; it simply reflects prolonged resistance to UVB rays.
What SPF Level Should You Choose?
SPF choice depends on skin type, lifestyle, and sun exposure intensity.
SPF 30
- A good starting point for daily use.
- Blocks about 97% of UVB rays.
SPF 50
- Provides stronger protection.
- Blocks about 98% of UVB rays.
- Often preferred by individuals with fair skin or sensitive skin barriers, and those spending extended time outdoors.
SPF 50+
- Suitable for high-sun environments, high altitudes, or individuals who prefer maximum protection.
- However, SPF alone is never enough—UVA protection must also be considered.
Why Is UVA Protection Important?
UVA rays:
- Penetrate glass,
- Reach deeper layers of the skin,
- Contribute to collagen and elastin breakdown.
- Indicators of UVA protection include:
- "UVA" label,
- “PA+++” notation,
- The “UVA circle” symbol in EU standards.
An effective sunscreen should provide:
- High UVB protection (SPF),
- Balanced UVA protection.
Mineral vs. Chemical Sunscreens: What’s the Difference?
Sunscreens are generally divided into two categories:
Mineral (Physical) Filters
Contain zinc oxide or titanium dioxide.
Reflect UV rays on the skin surface.
Often better tolerated by sensitive skin.
Chemical Filters
Absorb UV rays and convert them into lower energy forms.
Tend to have lighter textures and leave less white cast.
Both have advantages and limitations.
Suitability depends on skin type, sensitivity, and personal preference.
How to Choose the Right Sunscreen? Key Criteria
Choosing the correct sunscreen involves evaluating several scientific factors:
Broad-Spectrum Protection
Should protect against both UVA and UVB rays.
Compatibility With Skin Type
Dry skin: Creamy, moisturizing formulations.
Oily or acne-prone skin: Lightweight, non-comedogenic gels or fluids.
Sensitive skin: Mineral filters may be more tolerable.
Suitability for Intended Use
- Daily wear
- Beach or pool use
- Outdoor sports
- Under-makeup use
- Different formulations serve different purposes.
Water and Sweat Resistance
Important for active individuals.
Tolerability
A suitable sunscreen should not cause burning, stinging, or excessive redness.
How Often Should Sunscreen Be Reapplied?
- Reapplication is essential for maintaining protection.
- General dermatological principles:
- Sunscreen should be reapplied after sweating, swimming, or wiping the skin.
- During prolonged outdoor exposure, it is typically renewed every 2–3 hours.
- Even in indoor environments near windows, UVA exposure continues.
These are biological principles; personal recommendations should always be assessed by authorized healthcare professionals.
Is Sunscreen Necessary on Cloudy Days?
Yes. A large portion of UV radiation penetrates clouds.
Therefore, cloudy weather does not guarantee full protection.
Using sunscreen even during short outdoor exposure contributes to long-term skin health.
Frequently Asked Questions
What does SPF measure?
SPF indicates protection against UVB rays only.
What SPF level is ideal?
SPF 30 may be suitable for daily use; SPF 50 is preferred for more intense exposure.
Why is UVA protection important?
UVA rays contribute to aging signs and can penetrate glass.
Are mineral or chemical sunscreens better?
Both have benefits; the best choice depends on skin type and sensitivity.
Should sunscreen be reapplied during the day?
Yes—especially after sweating, swimming, or long outdoor exposure.
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