In 2016, as ISIS retreated from areas it had occupied two years earlier, it left behind desolation and carnage. In Qayyarah, an oil town less than a hundred kilometers south of Mosul, the group set fire to more than a dozen oil fields. The subsequent infernos burned for months, filling the air with toxic smoke and covering the town in a coating of black soot. Health experts warned that the effects of the pollution would last years, exposing locals, children in particular, to cancer-causing chemicals.