Sunblock and SPF are both related to sun protection, but they represent different aspects. SPF, or Sun Protection Factor, is a rating system that measures a sunscreen's ability to protect against UVB rays, a type of ultraviolet radiation that causes sunburn. Sunblock, on the other hand, refers to a type of sunscreen that works by creating a physical barrier on the skin to block UV rays.
Understanding SPF
SPF indicates the level of UVB protection a sunscreen provides. For example, an SPF 30 sunscreen allows approximately 3% of UVB rays to penetrate the skin, while an SPF 50 allows approximately 2%. While higher SPFs offer slightly more protection, the difference after SPF 30 is minimal. Many dermatologists recommend using a broad-spectrum sunscreen with an SPF of 30 or higher for daily sun protection. (Source: Should you use very high SPF sunscreen? MD Anderson Cancer Center) It is important to note that SPF only measures protection against UVB rays and does not directly reflect the level of protection against UVA rays, which contribute to aging and skin damage.
Understanding Sunblock
Sunblock is a type of sunscreen that uses physical ingredients, such as zinc oxide or titanium dioxide, to create a barrier on the skin. This barrier reflects and scatters UV rays, preventing them from penetrating the skin. (Source: Sunblock: The Basics) In contrast, some sunscreens use chemical filters that absorb UV rays. The term "sunblock" often gets used interchangeably with "physical sunscreen," highlighting the physical blocking mechanism.
Key Differences Summarized
| Feature | Sunblock | SPF |
|---|---|---|
| Mechanism | Physical barrier; reflects and scatters UV rays | Numerical rating of UVB protection |
| Ingredients | Zinc oxide, titanium dioxide | Various chemical and/or physical filters |
| Protection | Blocks both UVA and UVB rays (if broad-spectrum) | Primarily measures UVB protection; broad-spectrum sunscreens offer UVA protection as well. |
It's important to choose a broad-spectrum sunscreen (whether it is a sunblock or chemical sunscreen) with at least SPF 30 to protect your skin from both UVA and UVB rays.
