What is SPF, and how does SPF work?

Sun Protection Factor is referred to as SPF. It measures how well a sunscreen shields skin from ultraviolet (UV) rays from the sun. More protection is offered by sunscreen with a higher SPF.

UV rays are absorbed or reflected by SPF before they can harm the skin. UVA and UVB are the two types of UV rays that can harm skin. Sunburn is caused by UVB rays, while premature aging of the skin is brought on by UVA rays.

Approximately 97% of UVB rays will be blocked by sunscreen with an SPF of 30. In other words, if it takes you 10 minutes to get a sunburn without sunscreen, it will take you 300 minutes with SPF 30 sunscreen.

It is significant to remember that SPF does not completely block UV rays. Even with sunscreen, it’s still important to keep your exposure to the sun to a minimum and wear sun protection accessories like hats and sunglasses.

Here are some tips for choosing and using sunscreen:

  • Use sunscreen with an SPF of at least 30.
  • Look for a sunscreen that says “broad spectrum.” This means that it offers UVA and UVB protection.
  • 20 minutes before going outside, liberally apply sunscreen to all exposed skin.
  • Reapply sunscreen every two hours, or more frequently if you sweat or swim.
  • Avoid using sunscreen containing oxybenzone or octinoxate, which have been linked to health issues.

By following these tips, you can help protect your skin from the sun’s harmful UV rays.

Here is some additional information about SPF:

  • SPF does not indicate how long you can stay out in the sun without getting burned. It is a measurement of how much longer it takes to get burned with sunscreen than without.
  • SPF does not provide complete UV protection. It only protects against UVB rays, which cause sunburn; UVA rays cause skin damage but not sunburn. UVA rays accelerate skin aging, causing wrinkles and age spots.
  • A “broad spectrum” sunscreen protects against both UVA and UVB rays.
  • Reapply sunscreen every two hours, or more frequently if you are sweating or swimming, and limit your time in the sun even if you are wearing sunscreen.

Cheat sheet for sunscreens.

  • SPF 15 shields skin from 93% of UVB rays
  • SPF 30 blocks nearly 97%
  • SPF 50 blocks 98%
  • SPF 100 blocks 99%