ABSTRACT A study of the composition of the aerosol in the New York City atmosphere has been undertaken with the objectives of using the physical and chemical properties of suspended and settled dusts to characterize their sources@ and ascertaining the extent to which trace elements present in suspended dust are absorbed by New York City residents. In order to achieve these objectives we have: a) Determined the concentration@ trace element composition and particle size@ and solubility of aerosols and settled dust in New York City. b) Studied the temporal patterns of the variation of trace metal and ion concentration in total suspended particulate (TSP) and settled dust. c) Established the effects of meteorological parameters on the TSP and trace element concentrations. d) Defined the sources of the trace metals or ions. e) Related the aerosol trace element compositions to human tissue burdens.