10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Using Oxidation Flow Reactors for Studying the Effect of SOA Aging on Optical Properties and Health Effects
YINON RUDICH, Weizmann Institute of Science
Abstract Number: 343 Working Group: Oxidation Flow Reactor: Development, Characterization, and Application to Aerosols
Abstract Oxidation flow reactors enable studying the effects of aging on various aerosol properties. Here we will present a study on how aging affects the refractive index of non-absorbing SOA under NOx-free conditions. The optical properties of β−pinene and p−xylene SOA produced in an oxidation flow reactor (OFR), were studied using a novel white light-broadband cavity enhanced spectroscopy that measures aerosol extinction as a function of wavelength from 400 to 650 nm. It was found that these SOA are not absorbing in the visible range. The real part of the refractive index (RI), n, for these two types of SOA showed slight spectral dependence. With increased OH exposure, the real part of the refractive index first increased and then decreased, possibly due to an increase in aerosol density and chemical mean polarizability of SOA produced at low OH exposures, and a decrease in mean polarizability of SOA produced at high OH exposures, respectively.
In another study, we investigated the effect of SOA atmospheric aging on cell viability. SOA were formed in an OFR that simulates atmospheric SOA formation and aging dominated by OH radical oxidation under NOx-free conditions. Representative anthropogenic and biogenic volatile organic compounds (naphthalene and α-pinene, respectively) were used. SOA mass and chemical composition were characterized online using a scanning mobility particle sizer (SMPS) and high-resolution time of flight aerosol mass spectrometer (HiRes-Tof-AMS). The SOA were directed to an air liquid interface (ALI) cell exposure system, thus mimicking the deposition of fine particles in the lung. Slightly aged naphthalene-derived SOA (about 2 days) was slightly more toxic than SOA produced from α-pinene. We observed a significant increase in the SOA toxicity following chemical aging for both SOA types, and both aged (10 days) SOA had similar toxicity.