1. A mixture of fog and smoke or other airborne pollutants such as exhaust fumes.
2. A blend of smoke and fog.

• Smoke: The visible vapor and gases given off by a burning or smoldering substance; especially, the gray, brown, or blackish mixture of gases and suspended carbon particles resulting from the combustion of wood, peat, coal, or other organic matter.
• Fog: Condensed water vapor in the air at or near ground level.