Sun safety - how much is too much?

Some exposure to sunlight is essential for your health, but too much can be dangerous.
 
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  • Updated:10 Oct 2005
 

01.Sun safety

Woman applying sunscreen

What is UV radiation?

Sunlight is made up of various types of radiation. Across the full radiation spectrum, it’s mostly visible light and infrared heat that reach the earth’s surface. But it’s ultraviolet radiation, or UVR, that’s the most dangerous for your skin.

There are three types of UVR:  

  • UVA penetrates the skin, causes wrinkles and discolouration, and has been implicated in skin cancer
  • UVB is the most dangerous type, even though it’s mostly blocked by the earth’s ozone layer. Exposure to UVB causes sunburn, which can lead to permanent skin damage and cancer
  • UVC is less dangerous to skin and is in any case almost completely absorbed by the ozone layer, so it’s not a major cause for concern.

Please note: this information was current as of October 2005 but is still a useful guide today.


How to protect yourself from the sun

It's not hard to protect yourself from sunburn. Sunscreen, the right clothing, a hat and sunglasses and a bit of common sense are all you need.

Time of day

  • Keep out of the sun between 10 am and 2 pm (or 11 am and 3 pm during daylight saving)
  • Stay in the shade. But watch out for reflected UVR: indoor or grassy areas generally have less reflected UVR and therefore give better protection than areas with bright reflective surfaces like concrete, sand, snow or water
  • Clouds absorb or scatter some UVR, but not all of it. You can still get sunburnt on cool or cloudy days
  • Watch the UV index on weather reports as a guide to how much sun protection you'll need each day.

Sunscreens

If you're not using this much (as shown in the image to the right) - about six teaspoons - every time you put sunscreen on your whole body, you're probably not getting enough protection from UV. Sunscreen covering palm

  • SPF 30+ is best; it blocks about 97% of the sun's rays
  • Broad-spectrum sunscreens protect you against both UVA and UVB, ordinary sunscreens against UVB only
  • Water-resistant sunscreens are important if you're swimming, because UVR penetrates water for up to a metre. Reapply the sunscreen every two hours and after each swim (you're likely to towel some of it off anyway)
  • Use enough. There's reasonable evidence that a lot of people don't. About six teaspoons (30 mL) are needed for your whole body so if your head, neck, arms and legs (and maybe midriff) are all bared to the sun on a normal day you'll need a good proportion of that amount. It's a good idea to apply it once on the bits that aren't under clothing 20 minutes before you plan to go out and once again just before you go. You'll get better coverage, probably be using more like the right amount and be giving time for the sunscreen to interact and bond with your skin. Don't rub it into your skin; it should glide on like a coat of paint
  • Store your sunscreen in a cool place, as it can lose effectiveness if left somewhere hot like a car's glovebox for long periods. Throw away sunscreens that are past their expiry date, or that have gone gluggy or separated. The active ingredient may still be OK, but it may not spread evenly on your skin, which could result in patchy sunburn
  • Don't forget your lips: sunscreen can wear off them quickly. Alternatives are a lip balm with a high SPF or a thick zinc or titanium oxide sunblock
  • Manufacturers of sunscreens of SPF 4 or over have to be licensed by the Therapeutic Goods Administration and demonstrate that their products meet the claimed SPF, so you can be pretty confident that any SPF 30+ broad-spectrum sunscreen will do the job. Choose according to price and your personal preference
  • Sunscreens are quite safe, but young kids and people with sensitive skin may benefit from a low-irritant version.

Clothing

  • Medium-weight clothing will protect the areas it covers. Clothes that are too lightweight or have worn thin won't give good protection. Light colours let more light through than dark colours unless the material is thick enough to ensure the light is mostly reflected. So dark-coloured fabric usually provides better UV protection. But don't worry about this too much; a good medium or heavyweight white T-shirt, for example, will still protect your back
  • To protect yourself in the water, wear a shirt while swimming, but if it goes transparent when wet it'll be less protective. Consider special high-UPF swimwear, designed to be sunproof even in the water. (UPF is the clothing equivalent of SPF: for more see UPF.)
  • A broad-brimmed hat or legionnaire-style cap with a neck-drape, or even a scarf around your head and neck, will help protect your face and neck.

Sunglasses

  • Your eyes can also be damaged by long-term exposure to UVR, so put on a good pair of sunglasses along with your shirt, hat and sunscreen
  • Look for sunglasses labelled general-purpose or specific-purpose with traditional brown or grey lenses (rather than fashion or unlabelled sunglasses), as these offer the best UV protection
  • Ideally choose larger lenses: at least as big as a 20 cent coin with a wraparound style to cover the top and sides of your eyes
  • Normal prescription glasses (especially those with polycarbonate plastic lenses) give some UV protection, but for maximum protection consider getting prescription sunglasses as well. Alternatively, have your usual glasses treated with a clear UV-protective coating

Nutrition

  • There's evidence to suggest that a low-fat, high-fibre diet with plenty of vegetables and fruit and not too much red meat reduces the risk of certain types of cancer, and of course it'll help keep you healthy generally. However, connections between nutrition and skin cancer in particular aren't well understood, though one study has suggested that vitamin A may help reduce melanoma risk in some people.
 
 

 

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