Mustard gas often remains on the ground for several days.

We know he's dropping mustard gas on his own people.

And I find it very hard to forget about that mustard gas.

The 24th Battalion, he said, was under attack from mustard gas.

The effects of invisible mustard gas are not felt for at least 30 minutes.

He lost a leg in the war and was exposed to mustard gas.

Tests on a 55-gallon drum came up positive for mustard gas.

He doesn't mind the smell of mustard gas and roses.

Guthrie was the first to report on the effects of mustard gas.

Exposure to mustard gas was lethal in about one percent of cases.