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Aug 9, 20204 min read

You, UV and Sunscreen

Ah summer- talk about being in the sun. We’ve all heard about this magical lotion known as “sunscreen” which supposedly prevents us from becoming burnt crisps under the sun, but what exactly does sunscreen do for us? In the next few blog posts, we’ll be explaining the science behind sunscreen, practical applications, as well as social issues- yes you heard that correctly- social issues such as whitecasting and environmental considerations.

But what exactly is sunscreen? Sunscreen, also known as sunblock, can take various forms such as lotions, sprays, gels, powders, or even sticks (we know—strange)! While the composition and texture of these fascinating products can largely differ, all sunscreens have one thing in common—they protect your skin from the harmful ultraviolet (UV) rays of the sun.


Picture this: you’re lounging next to the pool under the bright summer sun with an ice cold drink in hand. Life is good, except one tiny detail... Unbeknownst to you, the sun is cooking you ever so slowly. Over time, exposure to UV rays causes skin damage. This can range from small features like sun spots or wrinkly skin to the deadliest form of skin cancer— melanoma.


UV rays are a form of radiation that can be emitted from both natural sources and artificial sources. The sun is the most common natural source of UV rays, while artificial sources include certain lamps, lasers or tanning beds.


There are 3 types of UV Rays: UVA, UVB, UVC. Of the three, UVA and UVB pose the greatest risk to health, as UVC is completely absorbed by the ozone layer and atmosphere. UVA is not as strong as UVB, but it is more constant throughout the year and penetrates into the dermis (middle layer of skin), causing indirect damage to DNA. UVB on the other hand, penetrates the epidermis (the outer layer of skin) and can cause direct damage to DNA; it has the potential to scramble your DNA like eggs. Because of this, UV rays are carcinogenic, meaning they can cause cancer. UVB rays are also the main cause of sunburns.


Sunscreen uses a variety of methods to prevent these rays from reaching your skin, which is a topic we’ll look into in our next post. But for now, let’s say we’ve convinced you to invest in some quality sunscreen. So what’s next? You must be imagining yourself standing in your local pharmacy store, eyeing the hundreds of sunscreen options occupying rows upon rows of shelf space. You may notice terms like SPF, broad spectrum, mineral, chemical…the list goes on. But what do all these things mean?


Sun Protection Factor (SPF) is an indicator of the level of protection a sunscreen provides against UVB rays. The United States Food Drug Administration (FDA) defines SPF as “the numerical ratio between the minimal erythema dose (MED- the UV dose required to cause a sunburn) of skin protected by 2 mg/cm2 of the tested [substrate] and the MED of unprotected skin after exposure to standard doses of a standardized solar simulated radiation”.



Breaking down the fancy lingo, SPF essentially tells you how much longer the sunscreen allows you to stay in the sun without getting sunburnt, as opposed to when you are not wearing sunscreen. This is a calculation for a given amount of sunscreen and intensity of UV radiation. For instance, if you normally burn in 20 minutes, using a sunscreen with an SPF 30 would mean it would take 10 hours of sun exposure before you burn. Although in practice, sunscreen tends to wear off quickly, which is a topic we will explore in our next post!



One common sunscreen myth is that the higher the sunscreen SPF, the more you are protected from the sun. For instance, using an SPF of 15 will help filter out roughly 93% of the sun's UVB rays, while an SPF of 30 will filter out 97% of the sun's UVB rays. Beyond SPF 30, increasing SPF values offer a minimal amount of extra protection.


Broad spectrum sunscreen refers to sunscreens that protect your skin from both UVA and UVB. Sunscreens don’t protect against UVC, since it is absorbed by the ozone layer.


In our next blog post, we’ll be covering practical applications of sunscreen as well as the different types.

 

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