Sun protection factor – protection, effect and importance in skincare

The sun protection factor (SPF) indicates how well a sunscreen protects the skin from UVB radiation. UVB radiation is the main cause of sunburn and contributes significantly to skin aging and the development of skin cancer. Adequate sun protection is considered the most important preventive measure in modern skincare.

Function and calculation

The SPF describes the ratio of the skin's natural protection time to the protection time provided by sunscreen. An SPF of 30 theoretically extends the protection time by a factor of 30. However, the actual effectiveness depends on the amount applied, skin type, perspiration, water, and friction. Dermatological societies recommend 2 mg per cm² of skin for adequate protection.

UVB and UVA protection

While the SPF only describes UVB protection, a product should also contain UVA filters . UVA radiation penetrates deeper into the dermis, promotes free radicals, and accelerates skin aging. Products with a UVA seal or "Broad Spectrum" label protect against both types of radiation.

Types of UV filters

• Chemical filters: absorb UV light and convert it into heat (e.g., octocrylene, avobenzone, Uvinul T 150).
• Mineral filters: reflect and scatter UV light (e.g., zinc oxide, titanium dioxide). They are particularly suitable for sensitive skin.
• Hybrid systems: combine both mechanisms for better protection and cosmetic aesthetics.

Innovations in formulation

Modern formulations utilize encapsulated filters or photostable blends to maintain consistent protection. Nature-based antioxidants such as astaxanthin, vitamin E, or green tea polyphenols enhance UV protection by neutralizing free radicals. Studies show that combinations of filters and antioxidants significantly reduce oxidative stress. ([mdpi.com](https://www.mdpi.com/1420-3049/27/15/4870))

Correct use and application

For complete protection, sunscreen must be applied generously and reapplied every two hours, especially after sweating or swimming. A common mistake is applying too little – this reduces the actual SPF by up to 50%. UV protection is also important on cloudy days, as up to 80% of UV radiation penetrates clouds.

Natural alternatives and myths

Natural oils like coconut or raspberry seed oil do offer minimal sun protection (SPF 2–5), but they are no substitute for tested UV filters. Plant extracts can provide antioxidant support, but they do not protect against DNA damage. Sustainable sunscreens are increasingly relying on non-nano zinc oxide and biodegradable formulations to protect aquatic organisms.

Health significance

Regular use of sunscreen has been proven to reduce the incidence of skin cancer and photoaging. A long-term study in Australia showed a 50% lower rate of actinic keratoses with daily SPF use. ([pubmed.ncbi.nlm.nih.gov](https://pubmed.ncbi.nlm.nih.gov/23475360/))

Conclusion

Sun protection factor (SPF) is a key component of any skincare routine. Effective protection relies on consistent application, sufficient quantity, and a combination of UVA/UVB filters and antioxidants – for healthy, youthful-looking skin.

Sources

1. Green AC et al. (2013): Daily sunscreen use and prevention of skin aging – Ann Intern Med 158(9)
2. Molecules (2022): Role of Antioxidants in Photoprotection and Sunscreen Formulations
3. Matts PJ et al. (2021): UVA protection factors in modern sunscreens – J Am Acad Dermatol
4. Young AR (2022): Photoprotection mechanisms of mineral and organic UV filters – Front Pharmacol
5. Front Med (2023): Sustainable Sunscreen Formulations and Ecotoxicology Review