What is SPF?

We all know that wearing sunscreen daily is critical for healthy skin. But there are still plenty of common sunscreen misconceptions - like what does SPF even stand for? If you are confused about how sun protection really works, we have you covered. Welcome to your guide to all things SPF. 

What is SPF?

SPF stands for Sun Protection Factor and is a measure of the sunscreen's ability to protect your skin from UVB rays.  As the SPF value increases, sunburn protection increases. Essentially, if it takes 1 minute for your unprotected skin with no sunscreen to start turning red [in the sun], using an SPF 30 sunscreen theoretically prevents reddening for 30 minutes or 30 times longer.

There is also a common myth that SPF is correlates to the time of sun exposure. For example, many people believe that an SPF 15 sunscreen allows them to stay in the sun 15 hours without getting sunburn. This is not true. SPF is not directly related to the time of exposure but to the amount of exposure. For example, the intensity of the solar energy impacts the amount of exposure. You could receive the same amount of solar energy for 10 minutes at midday that you would receive for one hour in the morning.  SPF is a relative measure of the amount of sunburn protection provided for eg; SPF 30 sunscreens provide more sunburn protection than SPF 8 sunscreens.

Solar intensity is also dependent on where you are geographically, with greater solar intensity occurring at lower latitudes. Your skin type, the amount of sunscreen you apply and how frequently you reapply also impacts the amount of sun that you're exposed to. 

Individuals with fairer skin are also likely to absorb more solar energy than those with darker skin under the same conditions. Whether you tan easily or not, sunscreen is critical for everyone. Skin damage from sun exposure happens over your lifetime even if you don't always burn. 

How much SPF do I need? 

With so many different SPF options, it can be hard to know which one is best for you. This is a general break down of the different protection provided from different SPF levels. 

• SPF 15 - this is the lowest SPF you can find and it blocks about 93% of UVB rays
• SPF 30 - this is the standard, recommended amount and it blocks about 97% of UVB rays
• SPF 50 - this level provides stronger protection and blocks up to 98% of UVB rays
• SPF 100 - this is the highest level of protection available, which blocks up to 99% of UVB rays

The general recommendation from dermatologists is that you should use SPF 30 or higher but it also depends on your specific skin type - whether or not you have fair skin, highly sensitive skin or a family history of skin cancer. Discover our options of dermatologist-recommended sunscreens with SPF 30 and up here. 

It’s important to note that SPF does not guard against UVA rays which contributes to premature aging and general skin damage. So when looking for a daily sunscreen, it's important to look for a broad-spectrum sunscreen in addition to SPF.  Broad-spectrum sunscreens (also known as full-spectrum sunscreen) protects against both UVA and UVB rays. Colorescience is a dermatologist-recommended skincare brand that offers a variety of broad-spectrum sunscreens. 

What does PA++++ mean?

PA stands for Protection Grade of UVA, so PA+ ratings measure the product's ability to block UVA rays. A PA rating indicates that you'll have some protection from UVA rays, with more plus signs indicating a higher level of protection. 

There’s currently no standardized system for evaluating PPD score, but like SPF, a sunscreen with a PPD rating of 10 should allow an individual to handle 10 times as much UVA exposure. However, since not all sunscreen brands use the PA rating system, you may see SPF and broad spectrum sunscreen instead, meaning that you're protected from both UVA and UVB rays.

What is the difference between physical & chemical sunscreen?

Physical sunscreen, also known as mineral sunscreen, forms a physical shield to reflect the harmful UVA and UVB rays with the active ingredients in mineral sunscreen being zinc oxide and titanium dioxide. Many mineral sunscreens today are formulated to leave no white cast and many mineral sunscreens are also available in tinted options now like the Colorescience Face Shield Flex or the Vivier Sheer SPF 30 Tinted Mineral Sunscreen. Learn more about tinted sunscreens here. 

On the other hand, chemical sunscreens absorb the UVA and UVB rays and uses a chemical reaction to convert them into non-damaging heat that is then released from the skin. The active ingredients in chemical sunscreen include oxybenzone, avobenzone, octisalate, octocrylene, homosalate, and octinoxate. A popular chemical sunscreen that's also available in a self-adjusting tint is the ZO Skin Smart Tone Broad Spectrum SPF 50 Tinted Sunscreen. 

Neither mineral sunscreen or chemical sunscreen is considered better than the other and the choice depends on your personal skin type and lifestyle needs. It's more important to use a sunscreen that provides broad-spectrum protection and you can apply daily and reapply frequently. 

How much sunscreen do I need?

Most people actually don't wear enough sunscreen. The amount needed for full protection is about a quarter size for your face and a shot glass worth for your body and remember that applying sunscreen isn't just necessary on sunny days but every day of the year. 

Do I need to reapply sunscreen?

Yes. Sunscreen wears off and becomes less effective with time. All sunscreen needs to be reapplied to limit the absorption of solar radiation. How frequently you need to reapply sunscreen depends on your activity, such as swimming, physical activity or heavy sweating but the general recommendation is to reapply every 2 hours if you're outside and every 4-6 hours if you're indoors. If you're using a water-resistant sunscreen, you can reapply every 40-80 minutes depending on the sunscreen label.  Reapplying sunscreen is easier than ever with sunscreen sprays and sunscreen powders, like this Colorescience mineral sunscreen powder duo. 

Now that you're equipped with more knowledge about sun safety, you can practice due diligence when shopping for a sunscreen. Remember, there is no sunscreen that will protect you from 100% from UV rays so it is important to combine sunscreen protection with other sun safety measures, like wearing protective clothing and seeking shade when exposed in the sun. 

Sources:
https://www.colorescience.com/blogs/learn/what-is-spf?srsltid=AfmBOoog1dPORl_z7Kau9UnU719GjgIwCErxvFlA9n2Nz1J5kbAEb848 
https://www.skincancer.org/skin-cancer-prevention/sun-protection/sunscreen/
https://www.fda.gov/about-fda/center-drug-evaluation-and-research-cder/sun-protection-factor-spf