Here comes the Sun, AHHHHHHHH!
Finally the mercury is rising and as far as the eye can see, people are taking off their kathmandu puffer jackets and beanies in exchange for sunnies and shorts. I’m sure the warm rays of sunlight feel great on your skin right now but should you be suspicious?
As summer approaches, the daylight hours are getting longer and the sunlight we’re exposed to is more intense. That light might look yellow but it is actually made up of all the colours we can see and all the invisible ones too! The colours we can see are just a range of wavelengths of light (380-740 nm) that the brain concludes is a colour. The light the sun emits outside this wavelength range includes Ultraviolet (UV) light which is made up of UVA and UVB rays, invisible to the human eye but still very real and dangerous.
The other kind of waves at the beach
UVA waves aren’t absorbed by the ozone layer that protects the earth, so are present in any weather while there’s daylight. They can penetrate through glass, clothes and past the deeper dermis layer of skin, causing premature ageing (wrinkles, sunspots and leathery skin) and skin cancer. UVA light can mutate DNA which changes the genetic code resulting in uncontrolled growth of cells that form cancers.
Left: Child enjoying the sun a little too much in the summer of 1985 Erin Stevenson O’Connor via Flickr. Right: Squamous cell carcinoma, known as skin cancer cells NIH image gallery via Flicker
UVB waves are partially absorbed by the ozone layer so are much more intense in summer. They don’t penetrate as deeply, generally stopped by clothing and glass before penetrating the surface layer of the skin, the epidermis. Here, they can change the genetic code in these cells, and if severe enough will cause the cell to literally kill itself. Yep, the cell recognises that it’s dangerous to its human and could become cancerous so it takes one for the team. This is scientifically called necrosis but you might know it as sunburn. This causes inflammation: the redness, pain and swelling you might be familiar with and if you’re particularly unfortunate the entire layer of dead skin cells will peel right off.
So water we going to do?
Today, a huge number of different Sunscreens are available: matte, sport, sprays, sheer, tinted, body, zinc, broad spectrum, sensitive, gels, scented, tanning, hydrating, reef-safe, lotions, roll-on, natural. But the most important label to look for is SPF which is the Sun Protection Factor
It’s a multiplication factor that shows how much longer you are protected from UV radiation that you would be without the sunscreen. It represents the percentage of UVB photons that it blocks which is 93% for SPF15, 97% for SPF 30 and 98% for SPF50. This really proves that any sunscreen you use is a lot better than none at all, so don’t worry too much about the lingo. Another important label to look for is ‘Broad spectrum’ which means the sunscreen contains ingredients that block light in the UVA and UVB range, which you know is pretty important.
Some Australian sunscreen favourites Joe shlabotnik via Flickr
But how does it even work?
Sunscreen can protect you through chemical or physical filters, neither of which are as scary as they sound.
Chemical filters form a film on the skin that absorbs UV radiation. The photons in the light break the chemical bonds in the active ingredient (usually Avobenzone or oxybenzone), which stops them from penetrating your skin. However once the sunscreen completely breaks down, they can generate free radicals and cause damage.
Physical filters scatter UV rays by deflecting them. Titanium or Zinc oxide blocks the photons and reflects them effectively blocking them from penetrating the skin, which is the reason you might get a white cast with a physical sunscreen. However for some people with sensitive skin titanium dioxide can cause skin discomfort and rash that might cause you to itch and rub off the sunscreen destroying its effectiveness.
The Australian Cancer Council recommends that sunscreen is applied every two hours, 15 minutes before sun exposure when the UV level is above 3. A full application is a 5ml teaspoon for each area (arm, leg, body front, back and face) for a total of 35ml for full body. But don’t fret too much, any application is better than none at all.
So Slop on some sunscreen, Seek shade, Slip on a rashy, Slide on some sunnies, Slap on a hat and enjoy the summer safely!