SPFväärtust

SPFväärtust, also known as Sun Protection Factor, is a measure of the effectiveness of a sunscreen in protecting the skin from harmful ultraviolet (UV) radiation. It is a numerical value that indicates how much longer the sunscreen can protect the skin compared to unprotected skin. For example, an SPF 30 sunscreen means that the skin will be protected from UVB rays for 30 times longer than it would be without sunscreen.

The SPF value is determined by the amount of UVB radiation that the sunscreen can block. It does not measure the amount of UVA radiation blocked, which is why some sunscreens with high SPF values may still allow significant UVA penetration. Therefore, it is important to choose a broad-spectrum sunscreen that provides protection against both UVA and UVB rays.

The SPF value is not a percentage of UVB protection. For instance, SPF 30 does not mean that 30% of UVB rays are blocked, but rather that the skin will be protected for 30 times longer than unprotected skin. This can be misleading, as it suggests a higher level of protection than is actually provided.

It is recommended to reapply sunscreen every two hours, or more frequently if swimming or sweating, as the protection provided by sunscreen can degrade over time. Additionally, sunscreen should be applied generously and evenly to all exposed skin, and it is important to choose a sunscreen that is suitable for the skin type and the activity being undertaken.