The primary difference between Sun Bum SPF 50 and SPF 70 lies in the slight increase in the percentage of ultraviolet B (UVB) rays they block and the theoretical duration of protection. While SPF 50 blocks approximately 98% of UVB rays, SPF 70 offers a marginally higher protection, blocking about 98.5% of UVB rays.
Understanding SPF: Protection Levels
SPF stands for Sun Protection Factor, and it's a measure of how well a sunscreen will protect your skin from UVB rays, which are the main cause of sunburn. It indicates how much longer it takes for sun-exposed skin to redden when using sunscreen compared to bare skin.
- SPF 50: Provides approximately 50 times the protection you'd have versus using no sunscreen at all, blocking about 98% of UVB rays.
- SPF 70: Provides approximately 70 times the protection you'd have versus using no sunscreen at all, blocking about 98.5% of UVB rays.
As you can see, the difference in the percentage of UVB rays blocked between SPF 50 and SPF 70 is only 0.5%. This marginal increase often leads experts to suggest that higher SPFs above 50 offer very little additional practical benefit.
Sun Bum SPF 50 vs. SPF 70: A Comparison
Here's a breakdown of the key differences and similarities:
| Feature | Sun Bum SPF 50 | Sun Bum SPF 70 |
|---|---|---|
| UVB Rays Blocked | Approximately 98% | Approximately 98.5% |
| "Times Protection" | Roughly 50 times vs. no sunscreen | Roughly 70 times vs. no sunscreen |
| Practical Benefit | Very high, excellent protection | Marginally higher than SPF 50 |
| Broad-Spectrum | Yes (protects against UVA and UVB) | Yes (protects against UVA and UVB) |
| Water Resistance | Typically 80 minutes (check label) | Typically 80 minutes (check label) |
| Reapplication | Essential every 2 hours or after swimming/sweating | Essential every 2 hours or after swimming/sweating |
What the Numbers Mean in Practice
While SPF 70 theoretically offers more protection, the real-world difference between 98% and 98.5% blockage is minimal. Sunscreens with an SPF higher than 50 tend to offer diminishing returns in terms of UVB protection.
- SPF 15: Blocks 93% of UVB rays.
- SPF 30: Blocks 97% of UVB rays.
- SPF 50: Blocks 98% of UVB rays.
- SPF 70: Blocks 98.5% of UVB rays.
This means that while SPF 70 offers a fraction more protection, it doesn't offer double the protection of SPF 30, for example. The most significant jump in protection occurs between low SPFs (like 15) and medium SPFs (like 30 or 50).
Key Considerations for Sun Protection
Choosing between SPF 50 and SPF 70 involves more than just the number on the bottle. Effective sun protection relies on several factors:
- Broad-Spectrum Protection: Always choose a sunscreen that states "broad-spectrum" on the label. This means it protects against both UVB rays (which cause sunburn) and UVA rays (which contribute to skin aging and increase skin cancer risk). Both Sun Bum SPF 50 and 70 are typically broad-spectrum.
- Water Resistance: If you're swimming or sweating, opt for water-resistant sunscreen. Sun Bum products usually offer up to 80 minutes of water resistance, but always check the label.
- Proper Application: This is perhaps the most crucial factor. Most people do not apply enough sunscreen. You should use about a shot glass full (one ounce) for your entire body, and a nickel-sized dollop for your face.
- Frequent Reapplication: Regardless of the SPF, sunscreen needs to be reapplied every two hours, or immediately after swimming, sweating, or towel drying. Higher SPF numbers can sometimes give a false sense of security, leading people to reapply less frequently, which negates any potential benefit.
- Other Sun Protection Methods: Sunscreen is just one part of a comprehensive sun protection strategy. Seek shade, wear protective clothing (long sleeves, hats, sunglasses), and avoid peak sun hours (typically 10 a.m. to 4 p.m.). For more information on sun safety, consult reputable sources like the American Academy of Dermatology.
Making Your Choice
For most individuals, Sun Bum SPF 50 offers excellent and sufficient protection against the sun's harmful rays when applied correctly and frequently. The incremental benefit of SPF 70 is minimal in real-world scenarios.
Consider SPF 70 if:
- You have extremely fair skin and burn very easily.
- You have a history of skin cancer or precancerous lesions.
- You will be exposed to intense sun for prolonged periods (e.g., at high altitudes, tropical climates) and are diligent about reapplication.
Ultimately, the best sunscreen is the one you will use consistently and correctly. Both Sun Bum SPF 50 and SPF 70 are effective options when used as directed. The U.S. Food and Drug Administration (FDA) generally recommends an SPF of 30 or higher for adequate protection.
