Daily Sun Protection: Why This Simple Step Makes All the Difference—Even in Winter

There's a question that comes up every fall, almost like a ritual: Do we really need to keep protecting ourselves from the sun once the days get shorter and the sky stays gray?

The answer lies in a simple observation, one that runs counter to a widely held belief—the idea that the sun is associated with heat, and the absence of heat with the absence of risk.

Two types of radiation, one simple step to take

The sun emits two types of ultraviolet rays, which do not act in the same way or at the same rate. UVB rays are the best known: they are the ones that cause sunburn, and their intensity varies greatly depending on the season. It is this variation that long led people to believe that we were safe in the winter. UVA rays follow a different pattern: according to the French Society of Dermatology, they account for about 95% of the ultraviolet radiation that actually reaches the ground, and their intensity remains nearly constant throughout the year, even on cloudy days. They pass through clouds and most types of glass, and penetrate deeper into the skin than UVB rays—without us feeling them, and without causing any immediate stinging or redness.

The gray sky doesn't make much of a difference

This lack of sensation largely explains why, for many people, sun protection remains a summer habit associated with the beach or the mountains. However, a cloudy sky blocks only a fraction of UV rays—thin clouds let most UVA radiation through, and even on gray days, cumulative exposure over a day of work or commuting remains significant. Snow, on the other hand, has the opposite effect: it can reflect up to 80% of UV rays, which explains why getting sunburned in the mountains in the middle of winter is not at all unusual.

What sets the winter exhibition apart from the summer exhibition is not its nature—it is its subtlety.

What cumulative exposure actually does, day after day

The skin does not react solely to a single, intense exposure—it retains a record of all exposures it has received over time, even minimal ones. UVA rays play a well-documented role in the gradual breakdown of collagen and elastin, the two proteins that give the skin its firmness and suppleness; ultraviolet rays are believed to be responsible for a large portion of the visible signs of skin aging observed on the face, far more so than aging due to age alone. Repeated unprotected exposure is also associated with the development of pigment spots. None of this happens overnight: it is a silent accumulation resulting from car rides and lunch breaks on outdoor patios, far more so than from a few weeks of vacation in the sun.

Why Consistency Matters More Than Intensity

This cumulative approach changes the way we should think about sun protection: not as a precaution reserved for times of intense sun exposure, but as a routine as natural as washing your hands. Sunscreen applied only on days with bright sunshine allows the majority of the UVA rays received over the course of a year to pass through without us even realizing it. Incorporating a light application of sunscreen in the morning takes just a few seconds once it becomes second nature—far less time than it takes to repair the damage caused by repeated sun exposure.

Cleanser — VIBRE PARIS

This step doesn’t replace anything: it complements what the skin absorbs and what it must then eliminate at the end of the day—sunscreen, sebum, urban pollution—which is why the cleanser mentioned above remains a full-fledged step in a skincare routine, rather than just a quick rinse. To understand why certain dark spots appear specifically as a result of unprotected sun exposure, our article on dark spots and hyperpigmentation explains the mechanisms involved.

Sources

• French Society of Dermatology (SFD) — fact sheets on UV radiation and sun protection
• Journal of the American Academy of Dermatology (JAAD) — Studies on photoaging and collagen degradation
• MSD Manual — Effects of Sun Exposure on the Skin, Professional Edition