By Sophia Eiley

Imagine it is a bright, sunny summer’s day. Before you venture outside, you remember that you haven’t put on any sunscreen. But you don’t give it any more thought than that, as, after all, you just want to get going. 


So was it a mistake? Well, yes – long story short, you got a nasty burn. And this causes you to reflect: “How does sunscreen protect me anyway? And besides the uncomfortable nature of a sunburn, what’s the harm?” Well, these conundrums are about to be explained. 


The sun creates both visible and invisible light. Invisible light can be both good and bad. Firstly, there is infrared radiation, which makes up around half of the sun’s energy that hits the earth and keeps us nice and warm and cozy. Sunburns are caused by ultraviolet (UV) light, which represents approximately 8% of the sun’s radiation and has shorter wavelengths than visible light. Most of the radiation is filtered by our atmosphere and the ozone layer. The amount of UV that we are exposed to depends heavily upon your location, the time of day, the weather and your surroundings.




The ultraviolet light photons from the sun’s light are mutagens that can damage our skin’s structural proteins and DNA. In turn, this causes cells to mutate and results in diseases like cancers of the skin. UV light from the sun can be placed in two categories: UVA and UVB. UVA light penetrates deeper into the skin than UVB light and is responsible for many of the visible signs of aging as well as tanning. It damages collagen, a structural protein, contributing, among other things, to our skin’s elasticity, causing wrinkles. UVB rays are the primary cause of sunburns. 


If you don’t think that is bad enough, both UVA and UVB rays can be absorbed by our DNA. This causes mutations that, if left unchecked, can result in various types of skin cancer including basal cell carcinoma and squamous cell carcinoma (both non-melanoma cancers) as well as melanoma cancers (the most severe).


Now you know all this I’m sure you are wondering: “What can I do to prevent this from happening to me?” And plainly the answer is to wear sunscreen.




Sunscreen contains a combination of inorganic and organic (carbon-based) chemicals which work together to reflect and absorb the UV rays from sunlight. It is important to pick a reliable and effective sunscreen because UV radiation can cause sunburns, premature aging of the skin and skin cancer. 


SPF (Sun Protective Factor) measures the ability of a sunscreen to protect your skin from UVB rays. Higher SPF numbers correspond to higher levels of sunburn protection. The FDA defines SPF around the amount of solar exposure, which differs from the commonly held belief that SPF is the time one’s skin is protected from the sun. This is because the amount of solar exposure we endure varies throughout the day depending on time and location. So, SPF should serve as more of a guideline rather than a rule of thumb. It is also worth noting that no sunscreen – no matter how high the SPF – is effective for more than two hours unless re-applied.


Sunscreens can be classified as both organic and inorganic. These classifications describe how different sunscreens and their contents protect you. Organic compounds, such as oxybenzone and octinoxate, absorb UV rays like sponges. On the other hand, inorganic compounds, which contain zinc oxide and/or titanium dioxide, protect the skin by reflecting and scattering UV light. A broad-spectrum sunscreen both absorbs and reflects UVB and UVA rays. This is achieved by blending the organic and inorganic compounds.


So there you have it, our dear readers. If you want to limit sunburns, prevent signs of aging, and reduce your risk of inflammation or skin cancers this summer, wear sunscreen!


[author] [author_info]Sophia is a grade 10 student at St. Michaels University School in British Columbia. She spends her time playing soccer and tinkering as a part of her school’s robotics team. In her future, Sophia plans to pursue mechanical engineering in post secondary education.[/author_info] [/author]




  1. Arlene Ruiz de Luzuriaga MD. Feel the burn? explaining the science of Sunscreen [Internet]. UChicago Medicine. UChicago Medicine; 2022 [cited 2022Aug2]. Available from: 
  2. Magazine S. How sunscreen protects your skin’s DNA [Internet]. Smithsonian Institution; 2017 [cited 2022Aug2]. Available from: 
Published On: August 7th, 2022 / Categories: STEMpowerment / Tags: , , /