And when it is not piling up, it is often burned in the open, releasing noxious smoke.

Burning of fossil fuels (coal, oil and gas) and wood may release dark smoke into the air.

The shape was hemispherical with a ring base and a hole for venting the fire and releasing smoke.

As it vapourises it releases white smoke - beryllium oxide.

The tube broke on impact, releasing coloured smoke to mark the impact point.

A boiler or furnace burning fuel normally releases smoke through a chimney.

There was grass, sun-dried, still containing sap but releasing heat as well as smoke.

Grenades have also been made to release smoke, tear gas and other gases, as well as illumination.

They stay on the ground and do not emit sparks, flares, any form of projectiles, or any sound, but may release smoke.

The fire sticks started to crackle and hiss as they released their moisture and smoke.