As the children are singing road songs, the bus passes through the toxic cloud.

Kirk found himself closest to Natira, and he pulled her aside, away from the toxic cloud.

The reason for this is due to a large toxic cloud approaching the Earth, threatening to wipe out all life.

"A toxic cloud would have formed and spread through the tunnels under the center of Rome," the paper reported today.

But the compound, solid at room temperature, gives off a toxic cloud when it contacts water.

In addition, a toxic cloud covered the city resulting in the town being evacuated.

Book 10: The school is abandon due to a toxic clouds passing by.

More than 200 gallons vaporized into a toxic cloud.

Otherwise, it's the story of a toxic cloud.