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Learn the lingo: What do UVA, UVB and SPF really mean?

We all know it’s important to slip, slop, slap — slip on a shirt, slop on sunscreen and slap on a hat — when you’re in the great outdoors. The hat and shirt part are easy, but with fancy sunscreen jargon like UVA, UVB and SPF, how do you know which one to choose? And what do all those letters mean anyway? Learn the lingo and get sun smart this summer with SheKnows.

woman soaking up the sun

What is UV light?

Sunlight contains lots of different rays. UV light is the electromagnetic radiation part of sunlight and it is invisible to the human eye. The effects of UV light are evident in the form of eye damage, suntans, premature ageing, sunburn, sun spots and, in some unfortunate cases, life-threatening skin cancers.

There are three types of UV light: UVA, UVB and UVC. UVC has the shortest wavelengths and most of the UVC rays, the super duper dangerous ones, don’t make it as far as the earth and are absorbed by the ozone layer. UVA and UVB do infiltrate the earth’s atmosphere and are responsible for contributing to the skin damage and subduing your immune system.

Levels of UV radiation are higher between 10 a.m. and 2 p.m. each day (during daylight savings time this is 11 a.m. to 3 p.m). During these hours it takes less time for the UV rays to harm your skin.

What’s the difference between UVA and UVB?

UVA rays

Almost 95 per cent of UV radiation penetrating the earth’s atmosphere is made up of UVA rays. Most people are subjected to big doses throughout their lifetime. UVA has a lower intensity than UVB, but the rays are more predominant and, even outside on a cloudy day or through glass, they are capable of doing damage year round.

UVA is the main ray which causes the skin to tan, which is essentially damage to the skin’s DNA. To reduce further injury to DNA the skin darkens. It also causes ageing wrinkles and unsightly sunspots.

UVB rays

These are the nasty rays sunscreenresponsible for sunburn and contribute to skin cancer. The rays are more intense than UVA but the intensity varies depending on the time of day, location and even the season. UVB can cause damage all year, even more so in higher altitudes as it reflects off snow and ice to burn twice.

What does SPF mean?

SPF stands for Sun Protection Factor which is a universal standard used to measure the effectiveness of sunscreen when applied evenly. The number alongside the letters SPF gives an approximate time you can stay in the sun wearing sunscreen without burning. For example, if you tend to start burning within 10 minutes of being in the sun, using an SPF30 sunscreen should enable you to stay in the sun up to 30 times longer. This is only a general indication as you will need to take into account your skin type, how much sunscreen you have applied and weather conditions. It also pays to reapply sunscreen at regular intervals and after being in the water, after drying off with a towel and excess sweating.

Now you understand the lingo, you should be ready to purchase a sunscreen that’s right for you.

More sun smart information

What do levels of sunscreen mean?
Tips on sunscreen application
Dangerous side effects of sun exposure

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