Wimbledon fortnight is here again. We always hope for a sunny two weeks to watch our tennis heroes, but cloudless skies can cause problems for both players and spectators. Although not always the hottest part of the year, late June and early July is the time when the Ultraviolet light (UVL) part of sunlight is at its strongest.
Although our bodies need UVL to form vitamin D in the skin, it's now a known fact that UVL is the main cause of skin cancer. Ageing of the skin is also primarily caused by chronic exposure to UVL, particularly the longer wavelengths, Ultraviolet A (UVA) which penetrate more deeply into the skin than the shorter wavelengths, Ultraviolet B (UVB) ,which causes sunburn and skin cancer. Look at your inner forearm and compare it with the appearance of the outer forearm and you'll clearly see what UVL is doing to your skin.
For those spending a day watching tennis at Wimbledon, your main aim should be to avoid sunburn. If your skin is very sensitive to UVL, the best protection is clothing. Hats with wide brims are great as they protect much of the face and neck, whereas baseball caps only protect the forehead and mid face. Darker coloured clothing and materials with a tight weave, such as denim, are the best sun blockers but not very practical in hot weather! UVL can penetrate easily through light, white cotton clothing which means that covered skin can also get burned. Sitting in the shade (if there is any) is helpful but remember that 60% of the UVL comes from blue sky and not the sun directly. So if you can see the sky, you are being exposed to large amounts of UVL.
Of course you can also use sunblock lotion, spray or cream. The sun protection factor (SPF) number is a rough guide as to how long you can stay in the sun before burning, compared to how long before you burn without the block. For example, SPF 30 means that, theoretically, if you burn after 30 minutes of exposure you could stay in the sun for 15 hours which is not actually very realistic. Sweating and time will gradually erode the effectiveness of the block. Most people don't apply a thick enough layer; so again, SPF 30 will not give this theoretical protection. Unfortunately, higher SPF numbers such as 50 won't give much more protection than an SPF 30 sunblock.
Some sunblocks also have UVA protection as well. The SPF number does not apply to UVA but UVA doesn't cause burning, only deeper damage that causes wrinkles. UVA may also have a role in causing cancer so it's best to use a combined UVA/UVB block.
So to enjoy a day at Wimbledon without burning, make sure you dress appropriately, sit in the shade if available, use a moderate SPF sunblock and re-apply after two to three hours. Remember that UVL penetrates haze and clouds, so you will only be safe from UVL if it's raining or if the sky is completely cloudy. Finally, wear sunglasses as UVL damages the eye and may cause cataracts.