Large Emissions of Low-Volatility Siloxanes during Residential Oven Use

Cooking is a source of airborne particles indoors and outdoors. A field study at a residential test house (HOMEChem) included two Thanksgiving-style cooking experiments involving prolonged use of an oven with a light use history. Large enhancements of airborne low-volatility siloxanes were observed by three in situ particle-phase instruments: a high-resolution aerosol mass spectrometer, a semivolatile thermal desorption aerosol gas chromatograph, and an extractive electrospray ionization mass spectrometer. The combination of these instruments permits the quantitative analysis of time-dependent processes and fates over a wide volatility range with high chemical specificity. Cumulatively, 17 and 8.5 mg of bulk siloxane material were emitted indoors and observed in airborne particles during the first and second Thanksgiving experiments, respectively; a peak 5 min average siloxane concentration of 58 mu g/m(3) was measured. Cyclic siloxanes D10-D18 were quantified, and D17 and D16 were the most abundant. We infer that heating of silicone materials inside the oven caused volatilization of cyclic siloxanes and cooler temperatures away from the oven resulted in condensation. Low-volatility siloxanes comprised a surprisingly large fraction of the total emitted submicrometer particle mass: 18% and 9% during the first and second Thanksgiving experiments, respectively. We estimate similar to 75% of the low-volatility siloxane mass was ventilated outdoors.