What is true about SPF ratings, the highest rating is 100% effective, the rating number means it will protect you that many times longer without sunscreen, and SPF ratings don't matter after 1 pm.

Answer 1

Let's break down the statements about SPF (Sun Protection Factor) ratings:

1. The highest rating is 100% effective: This is misleading. SPF does not equate to a percentage of effectiveness. An SPF of 30 blocks approximately 97% of UVB rays, while SPF 50 blocks about 98%. No sunscreen can provide 100% protection, as there are variables such as application thickness and user behavior that play a role.

2. The rating number means it will protect you that many times longer without sunscreen: This statement is partially true but can be misleading. For example, if you usually burn in 10 minutes, an SPF of 30 theoretically allows you to stay in the sun for 30 times longer without burning (10 minutes x 30 = 300 minutes). However, this assumes ideal conditions such as proper application and reapplication, which may not occur in real-world scenarios.

3. SPF ratings don't matter after 1 pm: This statement is not correct. SPF ratings always matter, regardless of the time of day. The sun's UV radiation can be strong at different times, and factors like location and season also influence UV exposure. Therefore, it’s important to use sunscreen consistently throughout the day when exposed to sunlight.

In summary, while there are some truths in the statements, they all have nuances that require further context to fully understand SPF ratings and their significance for sun protection.