UV radiation is invisible, and that’s exactly why it’s so often misjudged. Heat, brightness, and cloud cover all feel like useful clues — none of them reliably tell you how much UV exposure you’re actually getting. This is the science behind sun protection: what UV radiation is, how the UV Index works, and why the things you’d expect to keep you safe — shade, clouds, cool air — don’t tell the whole story.

Start Here

• What Is UV Radiation? — UVA, UVB, and why the UV Index matters more than temperature.
• How to Use the UV Index — what each UV level means, and how to build a protection routine around it.

Sun Damage, Explained Calmly

• Sun Damage You Can See — rough patches, brown spots, and the questions people ask when years of UV exposure start to show.
• What Is Actinic Keratosis? — a careful, evidence-based guide to AK: what it is, and why diagnosis matters.

Common Assumptions That Don’t Hold Up

Public health guidance keeps coming back to the same theme: comfort is not the same as safety. These short guides each tackle one common assumption:

• Clouds Don’t Block UV
• Cool Air Doesn’t Mean Low UV
• Shade Doesn’t Stop All UV

Once you understand how UV actually behaves, the next step is building your protection routine — see Sun Protection for sunscreen, clothing, and eyewear guidance, or jump straight to Start Here for the practical three-step plan.