Smog is in today’s headlines regularly, with vivid photographs of hoards of people wearing masks as they commute. There aren’t many things that acutely threaten the human ecosystem like smog, as the death tolls of the London, Donora, Shanghai, and Meuse Valley disasters show. This is an unfortunately topical book, chronicling several historic episodes—some lasting days, some years—through both focused text and powerful sidebars showing real statistics. Each spread has a fact box discussing what legal changes were made—and not made—following these events. The final chapter cites specific ways readers can help.