What are UV levels and how can you protect yourself?

Image source, AFP via Getty Images By Jennifer Clarke Published 28 June 2024 Updated 22 June 2026 As a period of extreme heat is forecast across the UK this week, UV levels are expected to be high in many areas. Some exposure to UV is essential for our wellbeing, but too much is damaging and can cause skin cancer. What is UV and why can it be dangerous? UV radiation is emitted by the Sun and penetrates the Earth's atmosphere. It enables our skin to produce essential vitamin D, which is important for the function of bones, blood cells and our immune system. But too much UV can be harmful. It can lead to skin cancer by damaging DNA in skin cells. UV also plays a substantial role in skin ageing, contributing to wrinkles and loosened folds. It has also been linked to eye problems , external , including cataracts. "Every exposure to UV, especially every sunburn, increases our risk of skin cancer," says Prof Dorothy Bennett, from St George's, University of London. "Melanoma, the most dangerous skin cancer, is now the fifth commonest cancer in the UK." UK's hottest May day record broken for second day in a row Published 26 May How long will the heatwave last? Published 27 May Why temperature records are being not only broken but smashed Published 27 May How is UV measured and what is the UV index? Levels of UV radiation vary throughout the day. The highest readings are in the four-hour period around "solar noon", when the sun is at its highest - usually from late morning to early afternoon. The UV Index (or UVI) is a measure of ultraviolet radiation used around the world. Values start at zero and can rise above 10. The higher the number, the greater the potential for damage to the skin and eyes, and the less time it takes for harm to occur. What do the different UV levels mean? In the UK, the UV index would typically be around 5-6 during the summer, with a maximum of 8 only in exceptional circumstances. Countries close to the equator can experience very high UV levels in the middle of the day, throughout the year. Nairobi in Kenya, for example, can have UV levels above 10 all year, according to the World Health Organization (WHO). Majorca in Spain normally hits nine in June and July. How can you protect yourself from UV radiation? Appropriate sunscreen is essential. Some sun protection is required when UK levels are medium (3-5) or high (6-7), the WHO says. Extra sun protection is required when UV levels are very high (8-10) or extremely high (11+). Children are more sensitive to UV radiation than adults, and therefore require additional protection at lower levels than adults. The NHS advises , external using sunscreen with an SPF factor of 30 or above and which offers at least 4-star UVA protection. It should be applied to all exposed skin, including the face, neck and ears - and head if you have thinning or no hair - ideally 30 minutes before you go out into the sun. As a guide, adults should aim to apply about six to eight teaspoons of sunscreen if c