Is SPF Important On A Cloudy Day? The Korean Approach To Sun Protection

Many people apply sunscreen only when the sun is shining or when they plan to spend a long time outdoors. But does a cloudy day really mean that the skin is safe from UV damage? In Korea, the approach to sun protection is more consistent and rigorous than in many Western countries. There, sunscreen is considered a daily necessity, regardless of weather conditions.

Many believe that clouds block sunlight, but this is not entirely true. While they can reduce the intensity of visible light, ultraviolet (UV) rays still penetrate. UVA rays are particularly dangerous, accounting for about 95% of all UV radiation and capable of passing not only through clouds but also through window glass. Unlike UVB rays, which cause sunburn, UVA penetrates deeper into the skin and induces oxidative stress that leads to the breakdown of collagen and elastin. This means that even on a cloudy day, the skin experiences damage that can eventually lead to early signs of aging and even increase the risk of skin cancer.

Why Does Korean Skincare Follow Strict SPF Discipline?

In Korea, using SPF is not just a cosmetic choice—it is a deeply rooted cultural practice. Historically, fair skin was regarded as a mark of refinement and higher social class, implying that a person spent more time indoors rather than laboring outdoors. This beauty ideal persists today, though it is now based not only on aesthetics but also dermatological reasoning. The Korean cosmetics industry and skincare experts emphasize that the most effective strategy against pigmentation and wrinkles is prevention, not remedying existing damage.

In Western countries, skincare often focuses on “treatment,” such as lightening pigmentation, reducing wrinkles, or correcting other damage. In contrast, Korea favors a preventative approach—SPF is seen as a daily habit to prevent issues before they arise. The cosmetics industry actively supports this mindset by continuously developing lightweight, invisible SPF formulas that easily integrate into daily routines. Moreover, dermatologists and beauty experts regularly highlight the importance of sun protection through social media and mass media, making SPF use in Korea almost second nature.

Is SPF Protection Necessary Indoors?

Window glass is not a complete barrier to UV radiation. While most windows block UVB rays, which cause sunburn, UVA rays penetrate almost unimpeded. This means that even indoors, skin can incur damage—especially if one frequently sits near windows or drives during the day. Studies show that people with workplaces near windows often exhibit more pronounced signs of aging on the side of the face more exposed to natural light. In Korea, this is seen as another compelling reason for daily SPF use, since skin needs protection both outdoors and indoors.

Additionally, blue light’s effects on the skin are receiving increasing attention. This light, emitted by computers, phones, and other screens, can cause oxidative stress and contribute to pigmentation. While its damage is not as intense as UV radiation, long-term exposure may have adverse effects. The Korean cosmetics industry is responding by creating products with additional filters that protect not only from the sun but also from artificial light. The question arises—is this merely a marketing gimmick, or a genuine protective measure?
Research on this topic is still limited, but growing attention to technology’s impact on the skin suggests that this trend could become a significant part of skincare in the future.

Mistakes Made in the West: Why Do Many People Under-Protect Themselves?

One of the most common mistakes is applying too little SPF. Studies show that most people use only about one-third of the recommended amount, significantly weakening the UV protection compared to what is stated on the packaging. SPF ratings are measured under laboratory conditions, assuming the use of 2 mg of product per square centimeter of skin. In real-life settings, people often apply SPF too thinly or unevenly, which means even SPF 50 may function more like SPF 15 or weaker. In Korea, this issue is addressed through clearer education—people are constantly reminded of the correct amount to use and the importance of reapplication.

Another frequent misconception is misunderstanding SPF numbers. Many believe SPF 50 provides twice the protection of SPF 25, but the reality is more nuanced. SPF 25 blocks about 96% of UVB rays, while SPF 50 blocks about 98%, so the difference is not as significant as it might seem. The problem arises when people using a higher SPF feel “invincible” and spend more time in the sun, unaware that UVA rays still cause damage. In Korea, not just the SPF number is emphasized, but also additional protective factors such as broad-spectrum filters, antioxidants, and physical protection like hats or parasols.

How to Properly Choose and Use SPF the Korean Way

One reason Korean SPF products are so popular is their lightweight, fast-absorbing formulas. In Western markets, many sunscreens are still oily, slow to absorb, leave a white cast, or feel unpleasant on the skin. Korea’s cosmetics industry invests in innovative textures—gel-based, water-based, or even spray-on SPF products that are invisible and convenient for daily use. This eliminates the excuse that SPF is “unpleasant” or “unsuitable under makeup.” If the product feels weightless on the skin, using it becomes a routine action rather than a burdensome task.

In addition to proper texture, SPF should be paired with other skincare components. Antioxidants like vitamin C or niacinamide are commonly used in Korean routines to enhance protection against free radicals. However, the most crucial aspect is reapplication. A single morning application of SPF does not protect the skin all day—its effect diminishes due to sweating, oil production, or mechanical wear. Korea has popularized convenient ways to reapply SPF throughout the day: SPF cushions, spray filters, or light, non-sticky lotions. These solutions remove the inconvenience and allow effective protection even when there’s no time for a full reapplication amid daily activities.

In the West, SPF is still often seen as a summer product meant only for sunny days or vacations. The Korean approach demonstrates that protection from UV rays is an investment in long-term skin health, not just a temporary fix. Consistent SPF use helps prevent not only pigmentation and wrinkles but also deeper skin damage that may only become visible decades later. The Western view on SPF is gradually evolving, but it has yet to become as ingrained as it is in Korea. The question remains: will Western consumers embrace the preventive model, or continue battling existing skin issues rather than preventing them in the first place?