Is there a difference between a tan and a burn on your skin? Is it just a colour difference or are you doing harm to the cells of your skin? What layers of the skin are affected?
Summer is on its way for us Northern hemispherians, which means it’s nearly time to whip on the tiniest item of swimwear you can find and bask in the sun’s warming rays. What could possibly go wrong?
It doesn’t sound comforting, but those warming rays are actually space-radiation generated by a huge nuclear fusion reactor millions of miles away. The sun bombards our planet with all sorts of radiation. Some of it is pretty useful – like the visible light that illuminates our days – but some of it is not so good for us.
One particularly dangerous type of radiation for our skin is ultraviolet light. This radiation (particularly a high-energy type called UV-B) wreaks havoc in our cells. We can’t actually see it, but it penetrates into the cells of our skin, where it damages our DNA. A bit of sun exposure will kill the odd cell – not something you’d notice – but too much will result in ‘sunburn’. When this happens, the body responds with inflammation: pain, swelling, heat and redness. Extra blood flows to the injured area to supply it with all the white blood cells and materials it needs to repair itself. This extra blood is what makes sunburnt skin so red.
So what is a suntan? It is simply the body’s natural defence against the damaging effects of UV. The skin produces melanin – a dark pigment – in response to UV radiation. Melanin absorbs UV radiation, preventing it from reaching the delicate DNA inside our skin cells. The more melanin, the darker your skin, and the better the UV protection. This is why darker-skinned people don’t get sunburnt as easily as light-skinned folk.
Nature’s sun protection offers no guarantee, however. Even with a dark tan, UV light can still damage DNA and cause sunburn – or worse. Occasionally faulty DNA can cause a skin cell to start growing uncontrolledly – resulting in skin cancer. The more often you get sunburnt, the more likely this is.
So the moral of the story is that both sunburn and suntan are signs that your skin is being damaged by UV-B radiation.
Getting sun exposure is important to ensure you get enough vitamin D, so don’t hide away completely. But keep in mind that it’s nuclear space radiation you’re bathing in, and take appropriate precautions!
Here are some top tips for staying safe in the sun.
Answer by Nick Waszkowycz