Earlier this yeat, TreeHugger posted a story on a fire pit made of 100% copper. Though not often stated, ordinary steel is commonly in 95 to 98% recycled range.
Wonder if these things bypass the indoor fireplace or woodstove emission standards?
=== Addendum to Original Post Follows ===
Wood burning impact on air quality is measured by EPA using the surrogate indicators of particulate matter, carbon monoxide, and sulfur dioxide. As the following links indicate, a relatively small fraction of the total land area of the US is at risk for exceedance of air quality standards for these. It is in such areas that limitations are put upon use and design of wood burning devices.
For a US map depicting counties which do not attain air quality standards for PM-10 Particulate Matter click here. The PM-10 non-attainment map indicates places where added smoke from fire places, grilles, wood stoves, and fire pits would be considered a health risk. For counties not meeting carbon monoxide standards, a hazard strongly influenced by transportation fuel combustion as well as by wood burning, click here. Finally, for counties with sulfur dioxide non-attainment problems click here.