BURNING UP THE ROAD

AS SOON AS THEY SAW THE PLUME OF gas, the Mexican truck drivers leaped out of their cabs and ran for the American side of the border. Acrylic acid, a toxic chemical, had leaked from a tanker waiting in line for U.S. Customs inspection, and the liquid was vaporizing as it gathered in a noxious pool. It was "chewing holes in the pavement," says Lee Thompson, who saw it all happen in early November at the border station outside Laredo, Texas. His hazardous-materials response team, fortuitously on the scene for a training exercise, rushed to prevent the highly flammable acid from...