Smart sewers for public health

Newsha Ghaeli reached down an open manhole one morning in April and grabbed a hose dangling in the rushing streams of the sewer below. As she pulled up the hose, she spotted a wad of toilet paper clinging to its end and recoiled in disgust, accidentally splashing a few drops of dirty water on strands of exposed hair sticking out from her face mask. A Cambridge, Mass., sanitation worker offered comfort: "A little caca won't hurt you," he said.