Sunscreen protects against UV rays.

The sun's ultraviolet rays are neither visible nor felt. They are important for the body's production of vitamin D, but they can also cause serious damage to the skin and eyes. The more intense and frequent the body's exposure to UV radiation, the higher the risk of skin cancer.

Yes, sun protection is important even on the first sunny days of the year. Just because it might still be cool doesn't mean the radiation can't be dangerous. The Federal Office for Radiation Protection (BfS) therefore advises keeping an eye on the UV index .

Many weather apps point to the index, which indicates values ​​on a scale of 1 to 11+. From a value of 3, which can be reached early in the year in certain regions around midday, eyes and skin should be protected. Long clothing, hats, sunglasses, and sunscreen will block intense radiation. Also helpful: seek shade.

These products contain substances that filter UV radiation. Most creams combine organic chemical and mineral filters. The former convert the incoming sunlight into heat, while the latter reflect the rays. Purely mineral sunscreens, which use physical filters such as titanium dioxide or zinc oxide, do not penetrate the skin but leave a protective layer on the surface.

People with sensitive skin or allergic reactions to chemical ingredients often turn to this option. However, various studies by product testers have shown that it is difficult, if not impossible, to guarantee reliable UV protection with zinc oxide alone.

The claim that sunscreen itself promotes skin cancer repeatedly appears on social media. The German Federal Institute for Risk Assessment (BfR) strongly refutes this claim: "Health impairments are not to be expected with sunscreens available in the European Union," it stated in the summer of 2024. There are no scientific studies suggesting health impairments from UV filters in the sunscreens.

The plasticizer DnHexP (di-n-hexyl phthalate) has been discovered in some products in the past. It has reproductive toxicity properties. The substance is prohibited as an ingredient in cosmetic products, but can enter the products as a contaminant. However, due to the small amounts involved, no health effects are expected, according to the BfR assessment.

So, no one should skip sunscreen out of concern. The risk of unprotected exposure to radiation is significantly higher. And you shouldn't skimp on the amount either, so that the specified sun protection factor can be fully effective. It's recommended that a 200-milliliter bottle be empty after an adult has applied the cream to the entire body about five times.

There is evidence that substances in sunscreens may be harmful to aquatic organisms such as corals and may exacerbate coral extinction, which is mainly caused by climate change.

According to the US National Oceanic and Atmospheric Administration (NOAA), the chemicals could also impair the growth of green algae, cause defects in juvenile mussels, and damage the immune and reproductive systems of sea urchins. In dolphins, the substances could accumulate in cell tissue and be transmitted to the juveniles, while in fish, they could reduce fertility and trigger genetic changes.

Nanoparticles in mineral creams, which are intended to prevent the white film on the skin after application, also have disadvantages. According to Spanish researchers, they could harm microorganisms in the sea.

Those who fail to protect their eyes from short-wave UVB radiation risk permanent damage to the cornea and retina. This can lead to corneal or conjunctivitis in the immediate future, and in the long term to clouding of the lens (cataracts) or even eye cancer. The World Health Organization recommends wearing sunglasses when the UV index is above 3.

This should be large enough to prevent light from reaching the eye from the sides. The tint of the lenses does not indicate the level of protection. Good glasses carry the label "UV-400," "100 percent UV," or the "CE" mark. The danger with dark lenses without UV protection: The pupils dilate behind them, allowing even more harmful radiation to reach the retina.

UV radiation from the sun is a significant risk factor for skin cancer. The Robert Koch Institute (RKI ) registered 23,560 new cases of malignant melanoma in Germany in 2020. Melanoma can quickly spread to deeper tissue layers. If not detected early, there is a high risk of spread to other organs. The RKI also reported around 209,000 new cases of non-melanoma skin cancer in 2020. A total of 4,106 people died from one of these two diseases in 2021. The statutory cancer screening program requires a skin examination every two years for men and women aged 35 and older.

Severe sunburns in childhood and adolescence, in particular, lead to skin damage in old age. The baby boomer generation is currently particularly affected. A report by the Barmer health insurance company attributes this to the fact that they paid less attention to protection during their childhood and that sunscreens were not as effective as they are today. The hope is that children born after 1980 were and are more careful in dealing with the blazing summer heat.

Based on the results of a 2024 study from Germany and Belgium , the answer is yes. According to the study, UV radiation has increased unexpectedly sharply in parts of Central Europe. Between 1997 and 2022, it rose by significantly more than 10 percent in the Dortmund region and by almost 20 percent in the Brussels area, according to the Federal Office for Radiation Protection, which conducted the study with two other institutions.

A 2023 paper by the Robert Koch Institute also states that UV exposure in Germany has increased significantly over the past decade (2010 to 2019) compared to the long-term average (1983 to 2019) - mainly due to less cloud cover in spring and summer.

Scientists predict that climatic conditions will exacerbate the situation, and that people could be exposed to even more sunlight in the future. Climate change is expected to result in less cloud cover and longer hours of sunshine on Earth. According to the German Meteorological Service (DWD), the number of hours of sunshine per year increased by almost 162 hours (about 10 percent) between 1951 and 2022.

Global warming may also play a role: At slightly higher temperatures, people might spend more time outdoors and dress lighter, exposing more of their skin to the sun's rays. In very hot weather, on the other hand, there's a tendency to avoid spending time outdoors or in the sun, which would help prevent skin cancer.