Thousands of mines on the island are still full of chemical gas and can be set off by passersby.

Vinyl products are pervasiveincluding toys, car interiors, shower curtains, and flooringand initially release chemical gases into the air.

This was a secretive unit where all sorts of chemical gases and munitions were tested.

His disease has apparently resulted from chemical gases used in the war.

The plot was said to involve the use of a relatively crude device for releasing the chemical gases.