Warm weather can often bring high levels of ultraviolet (UV) radiation. UV radiation is emitted by the Sun and penetrates the Earth’s atmosphere. Some exposure is essential for our wellbeing, but too much can cause skin damage.
UV is beneficial because it enables our skin to produce essential vitamin D. This is important for the function of bones, blood cells and our immune system. But we need to be careful about how much time we spend in the sunshine, warns Prof Dorothy Bennett, from St George’s, University of London.
Every exposure to UV, especially every sunburn, increases our risk of skin cancer. Melanoma, the most dangerous skin cancer, is now the fifth commonest cancer in the UK, the ongoing rise being attributed to sunbathing. UV radiation promotes skin cancer by damaging DNA in skin cells. It also plays a substantial role in skin ageing, contributing to wrinkles and loosened folds.
UV exposure has also been linked to eye problems, including cataracts. Levels of UV radiation vary throughout the day. The highest readings occur 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 standard, international measure of ultraviolet radiation. 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.
Countries close to the equator can experience very high UV levels in the middle of the day, throughout the year. Nairobi in Kenya 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. But the Falkland Islands in the South Atlantic never usually get above five, even in summer.
According to the WHO, no sun protection is required when levels are low. Some sun protection is required when levels are moderate. Extra sun protection is required when UV levels are high or very high. Children are more sensitive to UV radiation than adults, and therefore require additional protection at lower levels.
The NHS advises spending time in the shade when the sun is strongest, covering up with suitable clothing and wearing sunglasses, using sunscreen which is factor 30 or above and offers at least 4-star UVA protection, reapplying sunscreen regularly, and making sure babies and children are protected.
Global research shows people often miss parts of their bodies when putting on sunscreen. People often forget the side of their nose, the temples, and the upper chest. As a guide, adults should aim to apply about six to eight teaspoons of sunscreen if covering the entire body.
There is no safe or healthy way to get a tan, according to the NHS. Dr Shergill recommends using self-tan products instead. When you tan, ultraviolet light stimulates your skin cells to produce pigment to try and protect the DNA of skin cells – but that protection is minimal.
The amount of UV reaching your skin is not driven by the daily temperature. UV levels on a bright and breezy late April day in the UK will be about the same as a warm sunny day in August. Your skin can burn just as quickly whether it’s 30C or 20C. Don’t be caught out on cloudy days, UV will still penetrate thin clouds – so even if you don’t think it’s that sunny, you can still burn.
Yes, people with brown skin need to worry about UV radiation. The skin may look darker, but it doesn’t always behave that way from a protection point of view. The broader risks of eye damage and harmful effects on the immune system from too much UV radiation affect people of all skin colour.
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