Cosmic radiation comes from space. Only a small amount reaches the Earth's surface, but exposure is greater for people flying at high altitudes.

Changes in guidance and science seem to have little impact on millions of devastated lives. It’s a social crisis playing out behind closed doors, says Guardian columnist George Monbiot

What can a rare disorder tell us about human behavior?

One in 60 adults Fiji lives with HIV but a recent emergency declaration may help address key issues such as syringe sharing

John Green, the #1 bestselling author of The Anthropocene Reviewed and a passionate advocate for global healthcare reform, tells a deeply human story illuminating the fight against the world’s deadliest disease.