Field evaluation of a personal cascade impactor sampler (PCIS)

This paper presents the field evaluation of a personal cascade impactor sampler (PCIS). PCIS is a miniaturized cascade impactor, consisting of four impaction stages, followed by an after-filter. Particles are separated in the following aerodynamic particle diameter ranges: <0.25, 0.25-0.5, 0.5-1.0, 1.0-2.5 and 2.5-10 mu m. The PCIS operates at a flow rate of 9 liters per minute (l/min) using a very high efficiency, battery-operated light pump at a pressure drop of 11 in H2O (2.7 kPa). For field evaluation, the PCIS was collocated with other samplers including the micro-orifice uniform deposit impactor (MOUDI), scanning mobility particle sizer (SMPS) and aerodynamic particle sizer (APS) in Los Angeles and Claremont, CA. PCIS and MOUDI agree very well for coarse particulate matter (PM) (PM2.5-10) mass concentrations. The fine PM (PM2.5) mass as measured by PCIS is in excellent agreement with SMPS-APS measurement (similar to 1.02 times) and slightly higher (similar to 1.1 times) than the MOUDI measurements. Time-integrated (size fractionated) PM2.5 mass, inorganic ions (nitrate and sulfate), elemental carbon (EC) and organic carbon (OC) concentrations obtained with PCIS and MOUDI were found to be in very good agreement with few differences in the <0.25 mum size fraction, especially for OC and nitrate measurements. Near-continuous and size fractionated PM2.5 nitrate and total carbon measurements by PCIS and MOUDI using the ADI and Sunset labs monitors are in close agreement for all size fractions, indicating that any differences between MOUDI and PCIS measurements for time-integrated data might be due to artifacts associated with long-term sampling and not to differences in individual cut-points. The performance of the PCIS was also evaluated in wind tunnel tests at wind speeds up to 8 km/h. These tests showed that particle sampling efficiency and separation characteristics of the PCIS are unaffected by the wind speeds for particles up to 10 mum in aerodynamic diameter. (C) 2003 Elsevier Ltd. All rights reserved.