Every year in France, more than 80,000 new cases of skin cancer are diagnosed, the vast majority of which could have been prevented with proper sun protection. While sunlight is essential for vitamin D synthesis and mood, its ultraviolet rays are the leading cause of accelerated skin aging and the main risk factor for melanoma. Here is a comprehensive guide to enjoying the sun safely.
Understanding the dangers of UV rays
Solar radiation includes two types of ultraviolet rays with distinct effects on the skin. UVB rays penetrate as far as the epidermis and are responsible for sunburn, melanin production (tanning), and some damage to cellular DNA. UVA rays, more insidious, penetrate to the deep dermis: they are responsible for photoaging (wrinkles, age spots, loss of elasticity) and contribute to the risk of melanoma. Unlike UVB rays, UVA rays pass through glass and remain present year-round, even on cloudy days.
There are three main types of skin cancer linked to sun exposure: basal cell carcinoma (the most common, rarely fatal), squamous cell carcinoma, and melanoma (the most serious). The latter causes more than 1,700 deaths per year in France, according to the French Society of Dermatology, and its incidence has quadrupled in 30 years.
In the eyes, UV rays can cause photokeratitis (sunburn of the cornea), premature cataracts, and irreversible retinal damage. To understand skin structure and the mechanisms of UV-induced skin aging, our article "Understanding the Skin" explains skin function in detail.
Sun exposure rules
The fundamental rule: avoid all direct sun exposure between noon and 4 p.m. during the summer months, when UV intensity is at its peak. Outside of these hours, 15 to 30 minutes of sun exposure two to three times a week is sufficient to synthesize the necessary vitamin D intake (estimated at approximately 10,000 IU for 20 minutes of exposure in summer). In winter, short daily exposure is recommended to maintain adequate vitamin D levels.
The rule of thumb is a useful guideline: if your shadow is shorter than you are, the sun is dangerous. Wear a wide-brimmed hat, sunglasses with CE-certified UV filters, and lightweight, tightly woven clothing to cover sensitive areas during prolonged exposure.
Choosing and applying your sun protection
Understanding the SPF index
The SPF (Sun Protection Factor) indicates the level of protection against UVB rays. There are four levels: low (SPF 6 to 10), moderate (SPF 15 to 25), high (SPF 30 to 50), and very high (SPF 50+). The choice depends on your skin type, the intensity of the sun, and the duration of exposure. For fair skin (phototype I-II), children, and sensitive skin, an SPF 50+ is essential. For olive or dark skin (phototype IV-VI), a minimum SPF of 30 is still necessary.
SPF only blocks UVB rays. For complete protection (UVA + UVB), check that the product is labeled "broad spectrum" or displays the circled UVA logo. Mineral filters (zinc oxide, titanium dioxide) are recommended for children, pregnant women, and those with sensitive or acne-prone skin—they remain on the skin's surface and do not penetrate the bloodstream, unlike chemical filters.
How to properly apply sunscreen
The amount applied directly determines the actual level of protection. The rule of two milligrams per square centimeter (clinical dose) corresponds to approximately two teaspoons for the face alone, and a generous amount for the body. Most people apply two to four times less cream than necessary, thus reducing the actual SPF by half or more.
Apply sunscreen 20 to 30 minutes before sun exposure to allow the protective film to form. Reapply every two hours, and always after swimming or heavy sweating—even water-resistant products can't withstand vigorous rubbing. Don't forget those often-overlooked areas: ears, neck, tops of feet, hands, and lips.
Preparing your skin before sun exposure
Pre-sun scrub
A gentle scrub performed 24 to 48 hours before sun exposure removes dead skin cells that cause uneven tanning and less even application of sunscreen. It also stimulates microcirculation and promotes cell renewal. However, avoid scrubbing too close to or immediately after sun exposure—freshly exfoliated skin is more sensitive to UV rays.
Preparatory food
Certain nutrients strengthen the skin's natural resistance to UV rays from within. Beta-carotene (a precursor to vitamin A), found in carrots, mangoes, apricots, and bell peppers, stimulates melanin production and forms a light, natural shield against free radicals generated by UV radiation. Lycopene , found in tomatoes and watermelons (best absorbed when cooked with fat), protects dermal cells from oxidation. Vitamin C (citrus fruits, kiwi, bell peppers) and vitamin E (vegetable oils, almonds) are powerful antioxidants that neutralize free radicals induced by UVA rays.
These nutrients are not a substitute for sunscreen—no single food can provide sufficient SPF—but they do effectively strengthen the skin's natural defenses. To learn more about the link between diet and skin health, our article "5 Tips for Beautiful Skin" offers a comprehensive approach. UV-induced oxidative stress is also linked to a broader phenomenon, which our article "What is Oxidative Stress?" explains in detail.
Hydration
Sun exposure accelerates perspiration and skin water loss. Drinking at least 1.5 to 2 liters of water per day is essential to maintain skin hydration and prevent dryness. Avoid coffee, alcohol, and sugary drinks during periods of sun exposure: alcohol increases skin photosensitivity and promotes photosensitivity reactions; caffeine has a mild diuretic effect.
After sun exposure, apply a soothing and moisturizing treatment—pure aloe vera gel is particularly effective at calming minor skin inflammation and maintaining hydration. Avoid excessively hot showers, which strip the skin of its protective lipid film.
Frequently asked questions about sun protection
Does the sun really improve acne?
It's a common misconception. While the sun may temporarily dry out blemishes and improve their appearance in the short term, it actually thickens the stratum corneum in reaction to UV rays. These increased keratinocytes clog the follicles more effectively, often leading to more severe acne breakouts in the fall. Always use a non-comedogenic, lightweight sunscreen formulated for acne-prone skin.
Is it possible to take vitamin D while protecting oneself from the sun?
Yes. Unprotected exposure of 15 to 20 minutes (before 11 a.m. or after 4 p.m. in summer) on the forearms and legs is enough to synthesize a significant amount of vitamin D. Beyond that, protect yourself. In winter or for people at risk of deficiency, oral vitamin D3 supplementation is often recommended by doctors—it is more reliable and without the risks of prolonged exposure.
Should you wear sunscreen even on cloudy days?
Yes. UVA rays penetrate clouds and glass. Even on cloudy days, 80% of UV rays still reach the skin's surface. The basic rule: as soon as it's light out, UVA rays are present. In summer, a minimum SPF 30 sunscreen is recommended even when there is no visible sun during outdoor activities.