The Science Of A Sunburn

The Science Of A Sunburn

Sunburns: they’re the bummer of the summer. The time of year when temperatures are peaking – when you want to wear as little clothing as possible – also happens to be the time of year when it’s most dangerous to leave your skin exposed. It’s one of nature’s many cruel ironies.

Cruel, but also fascinating (as many dangerous things are – much to your parents’ chagrin!). For example, consider this: did you know a sunburn isn’t actually a “burn” per se? And by that I mean it’s not like the kind of burn your toast gets when you leave it in the toaster too long: a burn caused by heat, a reaction that occurs when thermal energy is applied to matter. No, a sunburn is something else completely; it can happen regardless of heat, which is why you can get a sunburn even in the middle of the winter.

This is because a sunburn is not a thermal burn but a radiation burn, which makes it totally different. Basically what’s happening with a sunburn is that your DNA is absorbing ultraviolet radiation and consequently getting damaged. Our DNA is what tells our cells how to replicate so when it gets damaged, the replications can go wrong. That’s how skin cancers like melanoma can develop. They’re essentially incorrectly replicated cells, which is pretty scary stuff! This is why you always want to be sun aware, especially during the summer: protect yourself by wearing sunglasses, applying lots of sunscreen and covering your skin whenever you can with a hat that shades your face.

But just why is it that sunburns are such a risk? Sunlight is so nice…and in the summer it’s everywhere! Yet it’s dangerous? Isn’t this a terrible way for our planet to be structured?

The answer, unfortunately, is that this is kind of our fault. You see, the earth actually has a built-in defense against ultraviolet (UV) radiation: the ozone layer, which is basically a band of protective gas that surrounds our planet and blocks out the sun’s harmful UV radiation.

That’s great, right? BUT…did you know that every day humans are destroying the ozone? Pollution – from things like cars, air conditioners, aerosol cans and landfills – contains gases that destroy the ozone. In fact, since the late 1970s,there’s been a steady decline of about four per cent per decade in the total volume of ozone in the earth’s stratosphere.


How does this happen?

Well, speaking in scientific terms, it’s the result of man-made halocarbon refrigerants, solvents, propellants and foam-blowing agents (substances more technically referred to as CFCs, HCFCs, freons and halons) being emitted here on earth and eventually floating up into the stratosphere. There they interact with UV radiation – the same stuff that gives us a sunburn – in a process known as photodecomposition. That’s a big word used to describe a chemical reaction in which a compound is broken down by particles of light (photons). This turns those man-man emissions into what are known as atomic halogens, a substance that reacts with ozone to deplete it. In other words, UV radiation reacts with man-made emissions to deplete the shield (i.e., the ozone) that would protect us from UV radiation, thereby letting more UV radiation reach us, which increases our risk of sunburn or skin cancer. I guess we can chalk this up to another of nature’s cruel ironies.

So what can we do about it? Well, for one thing, as mentioned above we can protect ourselves by wearing lots of sunscreen, a hat and sunglasses. We can also protect ourselves by planting more trees, which will provide shade from the sun’s harmful UV radiation.

These are simple solutions though and don’t really address the root of the problem. To do that, we need to start making serious changes in terms of how we live and what products we consume. For example, one of the major risks of increased surface-level UV is an associated increase in tropospheric ozone – that’s ozone gas in the lowest part of our atmosphere, the part closest to earth. Ground-level ozone is generally recognized to be a health risk and is toxic due to its strong oxidant properties. These risks are particular dangerous for young children, the elderly, and those with asthma or other respiratory difficulties. Therefore, since this ground level ozone is mainly produced by the reaction of UV radiation with exhaust from cars and trucks, this means one of the things we can do to reduce it is to drive less, walk or cycle more, or take public transit whenever we can. Similarly, we can choose to purchase products that are locally grown or made and don’t have to be shipped to us on exhaust-spewing trucks from far, far away.

These are just two of many possible solutions. What other solutions can you think of? Imagine all the good we could do if we all started to live differently now.