Siloxanes are organo-silicon compounds found in many industrial and consumer products like cosmetics, deodorants, and water repellants. More than one million tons of individual siloxanes, including those targeted in this proposal, are produced or imported in the US each year. As a result of their widespread use, they are found in wastewater and solid waste. They make their way into the environment through volatilization, wastewater discharge, and emission of landfill gases. This one-year pilot project focuses on the development of analytical methods for three cyclic siloxane compounds in air samples: octamethylcyclotetrasiloxane (D4); decamethylcyclopentasiloxane (D5); and dodecamethylcyclohexasiloxane (D6). The results will be used to develop a full-scale proposal for research on the emissions and transport of airborne siloxanes in Chicago and the surrounding Great Lakes.