What is SPF? Understand what it means for your sun protection.

SPF 30 or 60? SPF, the numerical value assigned to a sunscreen, is one of its main identifying features. It stands for Sun Protection Factor and indicates the amount of UV radiation it would take to produce sunburn when wearing a sunscreen compared to that without sunscreen. This post tells you how SPF works and how much SPF you need. Let's dive in.

What Does the SPF Number Mean in a Sunscreen? SPF Number Explained.

SPF indicates the level of protection against UVB rays. It relates to the amount of solar exposure. Contrary to popular belief, SPF is not related to the time of exposure to UV radiation. Wearing an SPF 15 sunscreen does not mean you can stay in the sun 15 hours without getting sunburn.

Although the amount of sun exposure is related to the time you're out in the sun, how much you're exposed to depends on other factors. Solar intensity is one. For example, you may be exposed to the same amount of solar energy when you're out for an hour at 9 a.m. and for 15 minutes at 1 p.m. Other factors that impact the amount of solar energy include skin type, the amount of sunscreen applied, and reapplication frequency.

So, what is SPF for sunscreen? The number tells you the percentage of UV rays the sunscreen can block. A sunscreen with a higher SPF rating blocks a greater percentage of UV light.

SPF 2 blocks 50% of UV rays

SPF 4 blocks 75% of UV rays

SPF 10 blocks 90% of UV rays

SPF 15 blocks 93% of UV rays

SPF 30 blocks 97% of UV rays

SPF 50 blocks 98% of UV rays

SPF 100 blocks 99% of UV rays

The minimum recommended for daily use is 15. Generally, the higher the SPF number, the better your protection against sunburn. SPF measures exposure to UVB rays, not UVA rays, which are capable of penetrating your skin and causing tans, damaging elastin and collagen, and generating DNA-damaging free radicals. Broad spectrum or full spectrum sunscreens provide protection against both UVA and UVB rays.

How SPF Works?

SPF is a precisely measured number, determined through a lab test. It is a reliable indicator of the level of sun protection.

What does SPF mean for different numbers?

An SPF below 15 is considered low sun protection. SPF 15 to 29 is medium protection. SPF between 30 and 49 offers high protection and anything above this number is very high protection. A sunscreen of SPF 50 or higher should block out 98-99% of UV rays when applied correctly.

Adequate application is important to mention when discussing what is SPF in sunscreen. Most of us do not apply enough of the product to reach the SPF mentioned on the bottle. This further emphasizes the advantage of using a higher SPF sunscreen. If you wear an SPF 15 and don't apply it correctly, you stand to receive less sun protection than what you might have by applying a higher SPF sunscreen in adequate amounts.

Everything Related to UV Rays

What is SPF when it comes to UVA and UVB rays? You already know SPF measures protection against UVB rays and a broad-spectrum product is best to avoid the harmful effects of both types of UV radiation. Here's more information on the impact of both on your skin.

UVA Rays

UVA rays can penetrate glass. So it isn't surprising that they can go through your skin and have damaging effects. Specifically, UVA rays can lead to premature aging over time. Avoidance measures such as wearing a higher SPF sunscreen daily and protective clothing and accessories when out in the sun, can help prevent fine lines and wrinkles. You could use a broad-spectrum sunscreen along with a moisturizer to limit UVA action and maintain the youthfulness of your skin.

UVB Rays

UVB rays do not penetrate as deeply as UVA rays; their action is limited to the top layer of the skin. They are notorious for causing sunburn. UVB rays cause more damage at higher altitudes, where the atmosphere is less dense and cannot filter as many rays. Applying sunscreen on a skiing or mountaineering trip is as important as wearing it to the beach. As prolonged exposure to UV radiation and frequent sunburns can increase the risk of skin cancer, wearing a high SPF sunscreen is highly advised.

Conclusion

Make sure to check a sunscreen's SPF to know the amount of UV protection you can count on. Make sure to wear an adequate amount of the product and reapply it during your day out when sweat can cause the sunscreen to run and drip. People who have fair skin or a history of skin cancer are also recommended to use a higher SPF sunscreen. With the right sun protection measures, you can maintain your skin's health for a lifetime.