Nanotechnology involves the manufacture and manipulation of tiny particles. Products that contain nanoparticles are now ubiquitous. Ian Illuminato discusses what this means for human health and the environment. Also, Mark Schapiro contrasts the EU's regulation of toxic chemicals in everyday products with the US approach.

It's a grand thought experiment rooted in one man's passion for the environment. In The World Without Us, Alan Weisman asks, What would happen if humans suddenly disappeared? Which human creations would last, and which would not? And would nature ever fully recover?