<p>Se-Jin Lee and Emily Germain-Lee explain a way to preserve bone and muscle mass during spaceflight.</p>

Hazards of ozone polution to birds

Welcome to Science Sessions, the PNAS podcast program. Listen to brief conversations with cutting-edge researchers, Academy members, and policymakers as they discuss topics relevant to today's scientific community. Learn the behind-the-scenes story of work published in PNAS, plus a broad range of scientific news about discoveries that affect the world around us.