A unique type of waste - air pollution control (APC) residues - has received increasing attention in China since the first large-scale incinerator, Shanghai Yuqiao municipal solid waste (MSW) incineration plant, was installed in the country in 2002. The APC residues of this particular plant are similar to other residues that will be produced in other incineration plants under construction in China. This work examines for the first time the benchmark contaminants of APC residues from the Yuqiao Plant. with reference to soluble sails. heavy metals and dioxins. Experimental findings reveal that the residues contained a marked amount of soluble salts. of up to 17.4-21.9%, (mostly chlorides), 0.98-1.5 ng TEQ/g ash of dioxins and various heavy metals. Lead is of particular concern, and requires stabilization before disposal. Heavy metal speciation schemes were implemented herein to determine the leaching characteristics. The correlation between the amounts of soluble salts or chemical speciation of the heavy metals and the leaching toxicity of these heavy metals in the residues is considered. (C) 2004 Elsevier B.V. All rights reserved.