<p>Gaige Kerr discusses racial disparities in atmospheric levels of nitrogen dioxide in the United States.</p>

Soil microbes and hybrid vigor

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.