Sunscreen Basics

In honor of summer, my next few posts will be part of a series on sunscreen.

In honor of summer, my next few posts will be part of a series on sunscreen. They’ll be broken up into five posts:

Sunscreen Basics
Sunscreen Facts and Myths
In photos: Sunscreen
Top 5 Recommended Sunscreens
On The Horizon: What’s New For Sunscreens
So the obvious place to start is with the basics. Let’s discuss SPF first.

What is SPF?

SPF is an acronym for Sun Protection Factor. In technical terms, it’s a numerical scale in which we can gauge our skin’s burning potential. Scientists measured this by exposing skin to artificial light and recording the results with and without sunscreen application.

But what does that really mean? Well, let’s say someone went out into the sun without any sunscreen, and they started to get pink (meaning, their skin was beginning to burn) after 5 minutes. If they had put on a sunscreen with SPF 15, they would have avoided getting burned 15 times longer. In this case, the skin would have been protected from burning for 75 minutes (5 x 15 = 75).

No Sunscreen


Sunscreen with SPF 15

Now there are obviously other factors involved such as time of day and UV index, but the SPF gives a good approximation of how much protection you are getting. It measures our rate of getting burned by UVB rays. Which brings us to our next question…

What are UV rays?

UV stands for ultra violet. They are invisible rays emitted as energy from the sun and reach the earth at different depths. UV radiation comes in three forms: UVA, UVB, and UVC. All are harmful to the skin, and we need protection against them.

UV rays

UVC rays are the shortest and most harmful rays. Thankfully, they are absorbed by the ozone layer and therefore do not reach the earth’s surface. UVA and UVB rays, however, do pass through the ozone and can cause substantial injury to the skin if left unprotected.

UVB rays are what generally cause sunburns and cancer. They primarily affect the uppermost layer of skin called the epidermis. This is where all the different types of skin cells are. By breaking down or altering the DNA of these cells, these harmful UVB rays can cause significant skin damage.

UVA rays are the more destructive of the two rays in terms of skin youthfulness. They can cause the skin to age at a rapid rate by creating brown spots and wrinkles, and decreasing elasticity. UVA rays penetrate down to the dermis (or lower layer of the skin) where it can break down collagen and initiate photoaging.

Physical vs Chemical

SunscreenThere has been an ongoing debate on which type of sunscreen is better: physical or chemical. In my opinion, the better sunscreen is the one that you will wear. Physical sunscreens are made up of minerals that sit on top of the skin, creating a barrier between your skin and the UV rays. They literally block or reflect the rays off of the skin. The most well-known ingredients in physical sunscreens are titanium dioxide and zinc oxide. Chemical sunscreens, however, have ingredients that absorb the UV rays and convert them to energy before the rays have a chance to reach your skin. Oxybenzone and mexoryl are the most common FDA-approved ingredients found in chemical sunscreens.

Physical sunscreens used to have a bad reputation of leaving that chalky, white paste on the skin. But the newer physical sunscreens blend in much better and some even have a tint so women can use it as foundation as well. Chemical sunscreens are typically odorless and colorless when applied to the skin. They also tend to cover a broader range of UVA and UVB rays for better protection, but the ingredients may cause skin irritation.

So my advice is to try both a physical and chemical sunscreen to determine which one is more suitable for your skin type. From my personal experience, oily and acneic skin do better with a chemical sunscreen while people with sensitive skin like physical sunscreens. Which one do you prefer?

Coming up: Sunscreen Myths and Facts. Find out why all sunscreens are not created equal.

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