Summer is here, and with it comes the never-ending battle against sunburns and skin cancer. Sunscreen is a crucial tool in protecting your skin from harmful UV rays, but there is often confusion and misinformation about how to properly use it.

In this article, we will provide a dozen answers to some of the most common sunscreen questions.

1. What is SPF, and what does it mean?

SPF stands for sun protection factor, and it is a measure of the amount of ultraviolet B (UVB) radiation blocked by sunscreen. For example, an SPF 30 sunscreen will block approximately 97% of UVB rays.

It is important to note that SPF only measures UVB protection, not protection from ultraviolet A (UVA) rays, which are also harmful to the skin.

2. How much sunscreen should I use?

Most people do not use enough sunscreen. A general rule of thumb is to apply one ounce (about a shot glass full) of sunscreen to cover your entire body. For just the face and neck, a quarter-sized amount is sufficient.

Reapplication every two hours is also necessary to maintain protection.

3. Can I use last year’s sunscreen?

Sunscreen does not last forever. The FDA requires sunscreens to remain effective for at least three years, but after that time, the active ingredients may break down and lose their effectiveness.

If your sunscreen is expired or has been exposed to high temperatures, buy a new one.

4. Is a higher SPF better?

A higher SPF does not necessarily mean better protection. While an SPF 30 sunscreen will block 97% of UVB rays, an SPF 50 sunscreen will block 98% of UVB rays. There is no sunscreen that can offer 100% protection.

5. How often should I reapply sunscreen?

Sunscreen should be reapplied every two hours, or more often if you are swimming or sweating. Even if your sunscreen is labeled as “water-resistant,” it is still necessary to reapply after being in the water for 40 minutes.

6. Can I get enough vitamin D if I wear sunscreen?

Sunscreen does reduce the amount of vitamin D your skin produces, but it is still possible to get enough vitamin D from other sources such as food and supplements. It is important to balance sun protection with vitamin D intake.

7. Can I use sunscreen on my baby?

Yes, it is safe to use sunscreen on babies six months and older. Use a moisturizing sunscreen with an SPF of at least 30, and avoid using sunscreen on babies under six months old.

8. Can sunscreen be harmful to the environment?

Some ingredients in sunscreen can be harmful to coral reefs and marine life, so it is important to choose a “reef-safe” sunscreen.

Look for sunscreens that are free of oxybenzone and octinoxate, two common ingredients that have been shown to damage coral reefs.

9. Can I use sunscreen on my hair?

Sunscreen can help protect your hair and scalp from the damaging effects of UV rays. Look for a spray or cream that is specifically designed for use on hair and avoid getting it in your eyes.

10. Can I use sunscreen if I have sensitive skin?

Yes, but it is important to choose a sunscreen that is labeled as “gentle” or “for sensitive skin.” Look for sunscreens that are free of fragrances, preservatives, and other potential irritants.

11. Can I use sunscreen if I have acne-prone skin?

Yes, but it is important to choose a sunscreen that is labeled as “non-comedogenic,” which means it will not clog pores. Look for a lightweight, oil-free sunscreen that won’t contribute to breakouts.

12. Is it ever too late to start using sunscreen?

It is never too late to start using sunscreen. While it is best to start protecting your skin from a young age, sunscreen can still offer benefits to older adults.

Sunscreen can help prevent skin cancer and premature aging, so it is never too late to start using it.