Qayyara – U.S. soldiers deployed at Qayyara military base near the northern Iraqi city of Mosul put on protective masks on Saturday after the wind started to carry toxic smoke from nearby sulphur plant which ISIS set on fire.

The precautionary measure was taken when the wind started to blow toxic smoke to the Qayyara airbase, south of Mosul, said two military U.S. officials.

Qayyara airbase is the main center where U.S. forces provide support to Iraqi troops conducting Mosul liberation operations. There are about 5,000 American forces in Iraq, but the U.S. military hasn’t revealed the actual number of troops at the airbase.

The sulphur plant near al-Meshraq, south of Mosul, was reportedly set ablaze by ISIS terrorists two days ago. Iraqi security official said that it could take about two or three days to set out the fire.

“The winds have actually shifted south, so, as a precautionary measure, the troops at Qayyara West have donned their personal protective equipment—continuing their operations at this point in time,” an official told Reuters.

The priority is to avoid any respiratory diseases because of the fumes. Reuters reported another official saying the air samples were sent to the U.S. Defense Threat Reductions Agency for testing.

An Iraqi commander, Qusay Hamid Kadhem, told AFP news agency two civilians had died from the fumes and “many others” had been injured.

Sources at Qayyara Hospital reported 1,000 people were being treated for breathing problems due to the fumes from Meshraq factory. Sources added that no death incidents have been reported.