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  • Writer's pictureCarissa Abraham

The Sunscreen Bible: Sunscreen 101

Updated: Nov 14, 2021

SPF: My favorite skincare product. It protects your body’s largest organ from getting cancer. Like most other skincare products, there’s a little bit of a science behind it and how it works to protect your skin. I’m here to break it down. Let’s call this The Sunscreen Bible.


SPF: Sun Protection Factor. The SPF number is a measurement of how much protection your skin has from UVA and UVB rays. The higher the number, the more protection, but no sunscreen will protect you 100%.

  • SPF 15 protects you from about 93% of UVB rays

  • SPF 30 protects you from about 97% of UVB rays

  • SPF 50 protects you from about 98% of UVB rays

  • SPF 100 protects you from about 99% of UVB rays

UVA: Ultraviolet A-Rays. These rays have a longer wavelength that directly impact how our skin ages when exposed to them. They do not cause sunburn, but they do cause the skin to brown. These are more dangerous because, while they do not cause the burn, they penetrate deeper into the skin.

UVB: Ultraviolet B-Rays. These rays have a shorter wavelength that are responsible for our skin burning.

Broad Spectrum: Broad spectrum means it helps protect against both UVB and UVA. UVA rays penetrate deep into your skin’s thickest layer (the dermis) and promote aging and wrinkles. UVB rays burn the two outermost layers of your skin and play a key role in developing skin cancer.

PA: PA followed by one or more plus signs refers to the protection grade of UVA. The “grading system,” which was created by the Japanese, is as follows:

  • PA+: Some UVA protection.

  • PA++: Moderate UVA protection.

  • PA+++: High UVA protection.

  • PA++++: Extremely High UVA protection.

Physical Sunscreen: Ingredients include titanium dioxide or zinc oxide (these are the ingredients that tend to leave a white film on the skin). Physical sunscreen works by sitting on top of the skin (like a barrier) in order to deflect UV rays away from the skin.

  • Offers protection immediately, no need to apply 20 minutes prior to exposure

  • Less likely to cause irritation, safer for sensitive skin

  • Less likely to clog pores, better for acne-prone skin

  • Needs to be reapplied more frequently, especially if sweating or in water

  • Thicker consistency

Chemical Sunscreen: Ingredients include oxybenzone, octinoxate, octisalate, avobenzone and more (more information on these ingredients below). Chemical sunscreen absorbs the UV rays as they hit the skin.

  • Thinner consistency, spreads easily

  • Requires application 20 minutes prior to sun exposure

  • May clog pores for oily skin types

  • Depending upon the ingredients, may irritate sensitive skin

Ingredients to Avoid:

I’ve done thorough research on sunscreen ingredients to avoid so that you don’t have to. These ingredients are toxic to us and the environment. Ever see sunscreen referred to as “reef safe?” That’s because it does not contain the ingredients below. Sunscreen is rapidly killing our reef system, which is a living thing! If it’s bad for our reef, imagine how bad it is for our skin?

Here are some ingredients to consider avoiding:

1: Chemical filters

These ingredients go by oxybenzone, avobenzone, octisalate, octocrylene, homosalate and octinoxate. I admit that I’ve used sunscreen containing one or two of these ingredients, but the NUMBER ONE ingredient I will forever avoid is OXYBENZONE. If you notice after a day in the sun any little bumps or pimples on your skin, you can thank oxybenzone because it burdens our liver and disrupts our hormones, which greatly affects our endocrine system.

2: Retinyl palmitate / retinol

These are forms of Vitamin A. Vitamin A maintains our skin tissue by helping the production of new skin cells. While retinol is great for anti-aging, when combined with the sun and UV rays it causes the antioxidants to break down and produce free radicals that damage our DNA. This is why any skincare specialist will tell you to stop retinol use at least one week before sun exposure. If you do hang in the sun after using retinol, you’ll find yourself quickly burned and red, even with sunscreen.

3: Parabens

Parabens act as preservatives to maintain a sunscreen’s shelf-life. They have the tendency to disrupt hormones and are associated with breast cancer. They’re also known to mess up your reproductive and developmental health. They have many different names, but luckily you can look for a PARABEN-FREE label on the bottle. Here are some paraben names to look out for (if you can remember them. Even I forget!): Butylparaben, Ethylparaben, Methylparaben, Propylparaben, Benzyl-parahydroxybenzoate (p-hydroxybenzoate), Methyl-parahydroxybenzoate (p-hydroxybenzate), Ethyl-parahydroxybenzoate (p-hydroxybenzoate), Propyl-parahydroxybenzoate (p-hydroxybenzoate), Butyl-parahydroxybenzoate (p-hydroxybenzoate), Parahydroxybenzoate (p-hydroxybenzoate)

4: Titanium Dioxide with nanoparticles and spray sunscreens

Titanium dioxide isn’t necessarily bad, but it’s the nanoparticles that are problematic. Nanoparticles absorb the sun’s radiation and have carcinogenic properties if inhaled. If you’re using a SPRAY sunscreen, avoid them with titanium dioxide because of how easily they’re inhaled. With that said, titanium dioxide is SAFER when used in a cream or when formulated without nanoparticles (non-nano).

I'll never stop emphasizing the importance of wearing sunscreen. Don’t forget your scalp is part of your skin, too, so wear a hat. Reapply sunscreen often regardless of the weather, and make sure you're drinking plenty of water, too!


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