QAYYARAH, Iraq — From the Makhmour military base, the route to Qayyarah crosses the Tigris River via a pontoon bridge that stops service at 6 p.m. and doesn't open again until late morning, after the road has been checked for improvised explosive devices planted overnight.

The town of Qayyarah, located 30 kilometers (18 miles) south of Mosul, and its still-burning oil wells were retaken from the Islamic State by Iraqi troops Aug. 25, after government forces managed to claw back the nearby Qayyarah West Airfield on July 9.

The regaining of the air base about 40 kilometers to the west of town was seen as a key victory in ongoing efforts to take back Mosul. It also enabled control of the road linking Mosul to the IS-held territories of Hawijah and Shirqat.

Months later, after troops entering from the north arrived to the eastern parts of IS-held Mosul on Nov. 1, the sky in Qayyarah continues to be blocked out most days by the billowing, choking black smoke and ubiquitous soot from over a dozen burning oil wells. They were set on fire by the militants as they were pushed back, leaving an environmental disaster and serious health threats to the town's inhabitants.