UV radiation is emitted by the Sun and penetrates the Earth’s atmosphere. Some UV radiation is essential for our wellbeing, and the sun’s rays provide warmth and light. But balance is key as UV exposure can also cause dangerous skin damage. 

Is UV dangerous?

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. However, UV is also dangerous because 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 has been linked to Ocular Cancer which is a form of melanoma and other eye conditions such as cataracts. UV may also reduce the body’s defence mechanisms against some diseases.

What is the UV index? 

Levels of UV radiation vary throughout the day. The highest readings occur in the four-hour period around “solar noon”, which is when the sun is at its highest spot in the sky – 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. Most mobile phones have weather apps that will show the UV level during the day so it’s always worth checking your phone to see what the local UV level is.

This image shows the UV index on the iPhone weather App at 13.00 hrs local time (to me).

What are the different UV levels?

 

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, will normally hit nine in June and July. But the Falkland Islands in the South Atlantic never usually gets above five in December and January (when it is summer in the southern hemisphere).

UV is always highest during the middle part of the day between 11am and 3pm . To ensure your skin is protected from UV, use all five forms of sun protection:-

• slip on a t-shirt.
• slop on sun cream with a protection factor of 30 or more.
• slap on a wide brimmed hat.
• slide on some quality sunglasses.
• shade from the sun wherever possible.

 

The Shadow Rule

Another handy tip to help you work out when the sun is strongest is the ‘Shadow Rule’. It’s simple and it works anywhere in the world. It’s also a fun way to talk to children about enjoying the sun safely.

Look at your shadow. If it is shorter than you, this means that the sun’s UV rays are at their strongest – in the UK, this is usually the middle of the day  when the sun is at it’s zenith (between 11am and 3pm). This is when you’re most likely to burn and need to think about taking extra care to protect your skin, especially if you get sunburnt easily.

You should take more care in the sun if you have one or more of the following:

• skin that burns easily
• a lighter skin tone
• light coloured hair or eyes
• lots of moles or freckles
• a history of sunburn
• a personal or family history of skin cancer

You’re the best person to know how your skin reacts to the sun. The more easily you get sunburnt, the more careful you need to be.

Sunburn doesn’t have to be raw, peeling or blistering. For people with darker skin tones, your skin may feel irritated, tender or itchy. For people with lighter skin tones, it may also go pink or red in the sun.

 

When do you need extra protection?

According to the WHO, extra sun protection is required when UV levels are: 

• 11+ (extremely high) 
• 8-10 (very high) 

Protection is required when levels are: 

• 6-7 (high) 
• 3-5 (medium)

No protection is required when levels are: 

• 1-2 (low)