Chromium-carrying ash captured by these devices is usually sent to ash ponds or land disposal sites. Chromium is released by volcanoes when they erupt, and by soils as they erode in wind and rain. These natural releases are larger than those from all human activities. Chromium released by human activities comes mainly from steel mills, metal production facilities, oil refineries, and cement plants. Ash particles carrying chromium settle to the ground after they are released into the air from power plants.
Most chromium reaches the ground through gravity and air turbulence.
Only small amounts of chromium dissolve in water and it does not seem to build up in the flesh of fish. Ash pond wastewater discharged into public waterways may contain small amounts of chromium, but these amounts are regulated by local permits. People are commonly exposed to chromium by breathing it in the air. They may drink water or eat food that contains small amounts of chromium. Industrial workers may breathe airborne chromium on the job or touch substances that contain chromium.