Bilde, Margerete

Bohgard, Mats

Lindskog, Magnus

Nilsson, Erik

Pagels, Joakim

Swietlicki, Erik

English

Lund University Publications

LUND UNIVERSITYPO Box 117221 00 Lund+46 46-222 00 00Ozone Initiated SOA Formation of Combustion AerrosolsPagels, Joakim; Lindskog, Magnus; Nilsson, Erik; Swietlicki, Erik; Bilde, Margerete; Bohgard,MatsPublished in:European Aerosol Conference 20092009Link to publicationCitation for published version (APA):Pagels, J., Lindskog, M., Nilsson, E., Swietlicki, E., Bilde, M., & Bohgard, M. (2009). Ozone Initiated SOAFormation of Combustion Aerrosols. European Aerosol Conference 2009, T108A18.Total number of authors:6General rightsUnless other specific re-use rights are stated the following general rights apply:Copyright and moral rights for the publications made accessible in the public portal are retained by the authorsand/or other copyright owners and it is a condition of accessing publications that users recognise and abide by thelegal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private studyor research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portalRead more about Creative commons licenses: https://creativecommons.org/licenses/Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will removeaccess to the work immediately and investigate your claim.  OZONE INITIATED SOA FORMATION OF COMBUSTION AEROSOLS   J. PAGELS1, M. LINDSKOG1, E. NILSSON1, E. SWIETLICKI2, M. BILDE3 and M. BOHGARD1 1Ergonomics and Aerosol Technology, Lund University, Box 118, 221 00, Lund, Sweden 2Department of Physics, Lund University, PO Box 118, SE-221 00, Lund, Sweden 3Department of Chemistry, Univ. of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark   Keywords:   INDOOR AIR, OZONE, AEROSOL MASS SPECTROMETRY, SOA FORMATION     Recently it has been shown that organic aerosols from incomplete combustion such as emissions from diesel engines are significantly transformed upon atmospheric ageing (Robinson et al. 2007). The particle mass emission factors increases due to gas-to-particle conversion upon exposure to UV-light. We hypothesize that these effects are generic also for other types of combustion aerosols and oxidants. The aim of this work is to test this hypothesis by investigating processing of indoor combustion aerosols upon exposure to elevated ozone concentrations.      Incenses and sidestream cigarette smoke of market leading brands were generated in a controlled manner in the Lund aerosol chamber (22 m3, stainless steel chamber). After a desired particle concentration (30, 60 or 100 g/m3) was established, the chamber was sealed. Two types of experiments (each 2-5 hours long) were performed, reference experiments with no added ozone and experiments where 100 or 400 ppb ozone was added after 20 min using an ozone generator (Ozone Technology). The ozone level was monitored using a UV spectrophotometric ozone monitor (model 49, Thermo Andersen). The particle size distribution and number concentration was determined using a scanning mobility particle sizer (model 3934, TSI Inc.). The chemical composition of fresh and aged aerosol particles was studied using a High-Resolution Time-of-Fight Aerosol Mass Spectrometer (HR-TOF-AMS; Aerodyne Research Inc.). The total mass concentration (PM1) was determined from the SMPS number size distribution using particle effective densities, which were empirically determined by comparing mobility (SMPS) and vacuum aerodynamic diameters (AMS).   Decrease in mass concentration over time in reference experiments were due to wall losses and some evaporation during the initial part of the experiment. As ozone was introduced into the chamber a rapid increase in mass concentration took place. For sidestream cigarette smoke the mass increase relative to the reference measurement is about 70% at 400 ppb ozone, and about 40% at 100 ppb ozone. Similar effects were found for incenses. It was found that concentrations of oxidised fragments detected with the AMS increased rapidly as ozone was added (fig 1). This shows that the condensed material is highly oxidised, compared to the hydrocarbon dominated primary particles. The elemental composition showed increased oxygen to carbon ratio and increased nitrogen concentration after ozone addition.       Figure 1. Time dependence of the ratio of two major fragments detected with AMS. m/z 44 (mainly CO2+) is a marker for oxidised organics, m/z 57 (mainly C4H9+) is a marker for hydrocarbon like organics.    These effects are rapid enough to be relevant for indoor air (10-15 min). Health effects of aged particles are almost certainly different from those of fresh particles. Future experiments are planned to involve other combustion aerosols, such as wood smoke and traffic emissions and other oxidants, for example UV-light.  This study was financed by the Swedish Research Council FORMAS  Robinson AL, Donahue NM, Shrivastava MK, et al. (2007) SCIENCE  315, 1259-1262 Cite abstract as Author(s) (2009), Title, European Aerosol Conference 2009, Karlsruhe, Abstract T108A18

Ozone Initiated SOA Formation of Combustion Aerrosols

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Ozone Initiated SOA Formation of Combustion Aerrosols

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