Development and Testing of Methods for the Continuous Measurement of the Concentration and Composition of PM0.1

Georgia Argyropoulou, Kalliopi Florou, Andreas Aktypis, Angeliki Matrali, Damianos Pavlidis, SPYROS Ν. PANDIS, University of Patras

     Abstract Number: 153
     Working Group: Instrumentation and Methods

Abstract
Ultrafine particles (diameter less than 100 nm) can translocate to sensitive organs of the human body (e.g., brain) and are thus primary suspects for enhanced negative health effects on humans. Measuring the chemical composition and physical properties of ultrafine particles continuously and accurately is particularly challenging because of their typically low mass concentration (PM_0.1) and susceptibility to interference from larger particles during the measurement processes. The few past PM_0.1 chemical composition studies have used cascade impactors. However, this method for PM_0.1 mass concentration measurement offers low temporal resolution, demands substantial labor, and its results might be affected by larger particles which have significantly more mass.

The Aerodynamic Aerosol Classifier (AAC, Cambustion) has the capability to function as a low-pass separator with selectable cut-off. We used the AAC, to separate PM0.1 from larger particles, followed by instruments that provide continuous composition measurements. An SP²XR (Droplet Measurement Technologies), for continuous black carbon measurements, a Xact 625i (SailBri Cooper, Inc)., for semi-continuous multi-metals measurements and a High-Resolution Time of Flight Aerosol Mass Spectrometer (HToF-AMS, Aerodyne Research Inc.), for PM_0.1 organic aerosol, particle density and source-apportionment analysis. The AAC was also combined with a Scanning Mobility Particle Sizer (SMPS) to provide information about the PM_0.1 density and shape factor.

Ambient PM_0.1 characterization measurements were conducted in different seasons in a suburban area in Greece. Most of the PM_0.1 (around 70%) was organic, with sulfates also representing a significant fraction. Black carbon contributed 5-10% on average, while the most prominent elements were Ca, K, Cl, Br, Fe, Zn and Ti. The temporal variation of concentrations, composition, and sources have been analyzed and will be discussed.