evidence: Sunscreens help prevent skin cancer, but some can harm the environment. Three recent behavioral science papers describe ways to boost visitors’ use of eco-friendly sun protection. That way, national park visitors can protect themselves and the places they care about too. [...] Apply sun protection when you know you'll be out in the sun. Be thorough when you apply it (no gaps). This will help avoid painful sunburns or even sun poisoning. It can reduce your risk of melanoma and other skin cancers. Don't forget places like ears, eyelids, lips and feet! [...] Chemical sunscreen has chemicals that absorb the sun’s rays, keeping them from reaching your skin. It has active ingredients like these: