Pollution is killing tens of thousands of people every day around the world. Cities across Asia and Europe have had to shut down and stop traffic to manage “Airpocalypse” pollution events when the air is unsafe for the people who live there. But air pollution is a major killer everywhere, even places we think of as safe. Pollution causes a range of respiratory diseases, and even short exposure can change how our DNA functions. New science is finding that microscopic bits of air pollution may be able to move from your nose directly into your brain, and could be causing dementia in humans. How unsafe is the pollution we can’t even see? Something in the Air explores these and other questions about the most precious resource we have—air.