LAUSR

Abstract. Decamethylcyclopentasiloxane (D5, C10H30O5Si5) is measured at ppt levels outdoors and ppb levels indoors. Primarily used in personal care products, its outdoor concentration is correlated to population density. Since understanding the aerosol formation potential of volatile chemical products is critical to understanding particulate matter in urban areas, the secondary organic aerosol yield of D5 was studied under a range of OH concentrations, OH exposures, NOx concentrations, and temperatures. The secondary organic aerosol (SOA) yield from the oxidation of D5 is extremely dependent on the OH concentration, and differing measurements of the SOA yield from the literature are resolved in this study. Here, we compare experimental results from environmental chambers and flow tube reactors. Generally, there are high SOA yields (> 68 %) at OH mixing ratios of 5 × 109 molec cm−3. At atmospherically relevant OH concentrations, the SOA yield is largely < 5 % and usually ~1 %. This is significantly lower than SOA yields used in emission and particulate matter inventories and demonstrates the necessity of OH concentrations similar to the ambient environment when extrapolating SOA yield data to the outdoor atmosphere.