UV Index: What should we know about the UV index and our skin?

What is the UV index?

The UV index (or ultraviolet index) is an international scale that measures the intensity of the sun’s ultraviolet radiation at the Earth’s surface. It indicates the extent to which this radiation can damage our skin and eyes. The scale starts at 0 and can exceed 11, with values above 6 already indicating a serious risk of sunburn, especially for more sensitive skin types.

Ultraviolet radiation is divided into three main spectra – UVA, UVB and UVC, with the latter not reaching the Earth. UVA penetrates deeper into the skin and causes aging and loss of elasticity, while UVB is responsible for tanning and sunburn. It is the UVB component that has the strongest influence on the UV index.

How is the UV index determined?

The global UV index is calculated based on several factors – the position of the sun, altitude, the thickness of the ozone layer, reflections from surfaces such as water, snow or sand, and even cloud cover. The World Health Organization and the World Meteorological Organization provide a standardized method for determining the values, which are updated daily.

For example, at the seaside around noon under clear skies, the UV index can reach 9 or higher. In the mountains, where altitude is greater, UV radiation is also stronger – something that is often underestimated by tourists and hikers.

For safe sun exposure, it is important to take timely protective measures, such as using two-phase sunscreen lotions that provide effective protection and deeply nourish the skin.

What are the levels and what do they mean?

The UV index is divided into five main levels:

• 0–2: low
  
  
• 3–5: moderate
  
  
• 6–7: high
  
  
• 8–10: very high
  
  
• 11+: extreme
  
  

If the value is below 3, sun exposure is considered relatively safe. At values between 6 and 10, however, protective measures are essential – using sunscreen, limiting time outdoors between 11 a.m. and 4 p.m., and wearing a hat. Levels above 11 are extremely dangerous and can lead to sunburn in just 10–15 minutes.

How does the UV index affect our skin?

Our skin is the first barrier against external influences, but that does not mean it is invulnerable. At high UV index values, the risk of acute and chronic damage increases. In the short term, this means sunburn, redness, pain and dehydration. In the long term – accelerated aging, hyperpigmentation and more serious skin conditions.

The lighter the skin, the higher the risk. Sensitive skin requires sun protection even at lower UV index values. The same applies to children and older adults. There is evidence that excessive sun exposure during childhood increases the risk of skin problems later in life.

How long is it safe to stay in the sun?

Safe time in the sun depends on skin type, the current UV index and the time of day. At a UV index of around 3–5, a person with fair skin may remain outdoors for 30–40 minutes, but with protection. At a UV index above 7, this threshold may drop to under 15 minutes.

It is important to distinguish between direct and indirect sun exposure – for example, even when you are under a beach umbrella, around 30–40% of UV rays still reach you through reflections from sand and water.

How can we protect ourselves effectively?

Sun protection is not simply about choosing yet another sunscreen. It is a complete approach. Using hydrating sunscreen lotions, for example, provides not only SPF protection but also skincare for skin exposed to the drying effects of the sun and salt water. A formula with nourishing ingredients helps restore the skin’s balance and makes it more resilient to external factors.

UV index and vitamin D: is there a golden balance?

Sun exposure also has its positive sides – the best known of which is vitamin D synthesis. Just 10–15 minutes in the sun daily are enough to produce the necessary amounts without taking on a risk of sunburn. This applies especially when the UV index is around 3–5. But here is the catch – at high values, the risk outweighs the benefit.

That is why specialists say that how much sun is beneficial depends on skin type, geographical location and season. The best advice? Choose times with a lower index – early in the morning or later in the afternoon, when the sun is weaker but still effective for vitamin D synthesis.

UV index in real time – how can we monitor it?

There are many mobile apps and websites that provide accurate and up-to-date information about UV levels in every area. They show not only the number, but also recommendations for protective measures – whether sunscreen should be used, how long it is safe to stay outdoors and even which parts of the body are most at risk.