Garbage normally includes wet food scraps and plastic, which are not allowed to be burned. Therefore, you may burn only the materials that are allowed to be open burned-namely, leaves, plant clippings, personal papers and clean, untreated wood. Burn barrels operate at low temperatures (400 to 500 degrees Fahrenheit), resulting in incomplete combustion of the wastes being burned.
Burning prohibited materials such as plastics, asphalt, rubber and other man-made materials generates additional hazardous air pollutants. A 1994 study done for the U.S. Environmental Protection Agency showed that each pound of garbage burned in a burn barrel emits twice as much furans, 20 times more dioxin and 40 times more particulates than if that same pound of garbage were burned in an incinerator with air pollution controls.
Burn barrels often emit acid vapors, carcinogenic tars, and "heavy metals" such as lead, cadmium and chromium, as well as unhealthful levels of carbon monoxide. The closer you stand to the burn barrel, the more of these harmful chemicals you inhale.
Residual ash is another result of incomplete combustion. Frequently, a significant portion of material in the barrel-especially at the bottom-is not burned up. Ash disposal outside of a sanitary landfill can cause problems sooner (for those immediately exposed) or later (for example, if water contacting the ash becomes contaminated and gets into groundwater and/or surface water).
Materials that may not be burned in a burn barrel-such as tires, plastics and rubber-also should not be burned in a furnace, wood stove or similar home heating system.