Understand SPF Levels and Make The Best Choice
Sunscreens have different SPF levels, and you need discernment to make the best decision for your skin.
This article will answer the most common questions about SPF levels and disperse a few myths. Let’s get started.
What is SPF?
SPF stands for sun protection factor.
The number beside it indicates how effectively sunscreen protects the skin against UVB rays responsible for sunburns and skin cancer.
Sunscreens are tested the same way worldwide to discover the SPF number.
Skin without sunscreen is exposed to UV light to see how long it takes to cause a minimal sunburn.
Sunscreen is then applied on the skin that is exposed again to UV rays to determine the time skin can be exposed to sunrays without being burned.
A simple formula is used to get the SPF number. The number of seconds it takes for the skin to slightly burn when protected by a sunscreen is divided by the number of seconds it takes to slightly burn when there is no sunscreen applied.
Say it took 500 seconds for the skin to burn with sunscreen, and 10 seconds to burn without it. 500 is divided by 10, which is 50. The SPF is 50.
The product is then labelled with the appropriate SPF value.
The myth that an SPF of 30 means you can be in the sun for 30 minutes or an SPF of 50 means 50 minutes is not correct.
SPF is not a specific amount of time. It refers to how much longer you can be in the sun in comparison to the days you don’t wear sunscreen.
How to find your SPF?
How does this apply to you? Find out how long you can be in the sun before your skin slightly burns.
Depending on your skin type, skin sensitivity and sun intensity you may burn in 5, 10 minutes or longer. It is different for different people.
Once you know how long you can be exposed unprotected multiply that number by the SPF factor of the sunscreen you are currently using, and you have the duration of your time in the sun protected.
Let’s say your skin burns after 10 minutes without sunscreen. If you’re using SPF 30, you can safely stay in the sun for 5 hours (30 x 10 minutes = 300 minutes).
But this is not a guarantee that you are protected during the entire time.
Most sunscreens wear off long before this calculated time, due to exposure to the elements as well as insufficient product application.
So, it is recommended that you reapply every two hours.
Also, note that SPF relates to a sunscreen’s ability to shield only against UVB rays.
The SPF on the label doesn’t say anything about a sunscreen’s ability to block UVA rays.
Sunscreen needs to be labelled as broad spectrum to protect against both UVB and UVA rays. And the UVA protection needs to account for at least 1/3 of the UVB protection.
You need to look for a broad-spectrum value.
Does higher SPF levels means higher protection?
Sunscreens are made in a wide range of SPFs. Higher SPF numbers mean greater protection from UVB rays.
But the SPF scale is not linear, meaning that an SPF of 30 does not provide double the protection of an SPF of 15 and an SPF of 50+ is not a lot more effective than a sunscreen of SPF 30.
Also, no sunscreen can protect against 100% of UV rays. Even a broad spectrum SPF 50+ won’t block all the damaging radiation.
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- No sunscreen allows for 100% photons to enter the skin and cause damage.
- SPF 15 blocks 93% of UVB rays. Only 7 photons enter the skin.
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- SPF 30 blocks 97% of UVB rays. Only 3 photons enter the skin.
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- SPF 50 blocks 98% of UVB rays. Only 2 photons enter the skin.
While you may not be doubling your level of protection, an SPF 30 will block more radiation that an SPF 15. So, most dermatologists recommend using an SPF 30 or higher.
To maximize safety in the sun, other measures need to be used together with sunscreen. Apply a lip balm that contains SPF, avoid the sun in peak hours and wear UV protection sunglasses.
Disclaimer: This article is informational only. This article does not provide medical advice, diagnosis, or treatment. Any information published on this website or by this brand is not intended as a substitute for medical advice, and you should not take any action before consulting with a healthcare professional. If you have questions or concerns about caring for your skin, you should make an appointment to see a board-certified dermatologist.
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