Air Force Institute of Technology AFIT Scholar Theses and Dissertations Student Graduate Works 3-11-2011 Evaluation of XMX/2L-MIL Virtual Impactor Performance and Capture and Retention of Aerosol Particles in Two Different Collection Media Jon E. Black Follow this and additional works at: https://scholar.afit.edu/etd Part of the Occupational Health and Industrial Hygiene Commons Recommended Citation Black, Jon E., "Evaluation of XMX/2L-MIL Virtual Impactor Performance and Capture and Retention of Aerosol Particles in Two Different Collection Media" (2011). Theses and Dissertations. 1518. https://scholar.afit.edu/etd/1518 This Thesis is brought to you for free and open access by the Student Graduate Works at AFIT Scholar. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of AFIT Scholar. For more information, please contact [email protected]. EVALUATION OF XMX/2L-MIL VIRTUAL IMPACTOR PERFORMANCE AND CAPTURE AND RETENTION OF AEROSOL PARTICLES IN TWO DIFFERENT COLLECTION MEDIA THESIS Jon E. Black, Major, USAF, BSC AFIT/GIH/ENV/11-M01 DEPARTMENT OF THE AIR FORCE AIR UNIVERSITY AIR FORCE INSTITUTE OF TECHNOLOGY Wright-Patterson Air Force Base, Ohio APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED The views expressed in this thesis are those of the author and do not reflect the official policy or position of the United States Air Force, Department of Defense, or the United States Government. This material is declared a work of the United States Government and is not subject to copyright protection in the United States. AFIT/GIH/ENV/11-M01 EVALUATION OF XMX/2L-MIL VIRTUAL IMPACTOR PERFORMANCE AND CAPTURE AND RETENTION OF AEROSOL PARTICLES IN TWO DIFFERENT COLLECTION MEDIA THESIS Presented to the Faculty Department of Systems and Engineering Management Graduate School of Engineering and Management Air Force Institute of Technology Air University Air Education and Training Command In Partial Fulfillment of the Requirements for the Degree of Master of Science in Industrial Hygiene Jon E. Black, MS Major, USAF, BSC March 2011 APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED AFIT/GIH/ENV/11-M01 EVALUATION OF XMX/2L-MIL VIRTUAL IMPACTOR PERFORMANCE AND CAPTURE AND RETENTION OF AEROSOL PARTICLES IN TWO DIFFERENT COLLECTION MEDIA Jon E. Black, MS Major, USAF, BSC Approved: __________//Signed//_________________ __07 Mar 2011__ Lt Col Dirk P. Yamamoto, PhD (Chairman) Date __________//Signed//________________ __04 Mar 2011__ Lt Col Jeremy M. Slagley, PhD (Member) Date USAF School of Aerospace Medicine Technical Services Branch __________//Signed//________________ __07 Mar 2011__ Charles A. Bleckmann, PhD (Member) Date __________//Signed//___________________ __04 Mar 2011__ Capt Casey W. Cooper, MS, MBA (Member) Date USAF School of Aerospace Medicine Risk Analysis Division AFIT/GIH/ENV/11-M01 Abstract The United States Air Force uses the XMX/2L-MIL (XMX) high volume air sampler to collect samples for biological analysis. The XMX uses a virtual impactor to concentrate particles 1.0 to 10 µm in size into a secondary flow prior to sample collection using a liquid impinger in a collection tube. There are no known published studies regarding virtual impactor inter-instrument variability, effect of reducing the secondary flow on particle concentration, or capture and retention efficiency (CRE) of particles in the collection media performance characteristics when using the XMX. These performance characteristics were evaluated by lofting test aerosols of Arizona Road Dust or fluorescent polystyrene latex (FPSL) spheres into a 14 m3 test chamber, measuring the chamber and post-virtual impactor particle concentrations using aerodynamic particle sizers, and measuring the concentration of FPSL spheres captured and retained in the collection media using a fluorometer. Notable findings include detection of significant inter-instrument virtual impactor variability, significant difference in particle concentration at reduced secondary flow, and significant differences in CRE due to particle size and secondary flow. This research demonstrates that when using an XMX limit of detection precision is suspect and the importance of collecting and analyzing multiple samples for improved risk assessment. iv Acknowledgements I would like to thank my advisors, Lt Col Jeremy Slagley and Lt Col Dirk Yamamoto, for their guidance and support throughout the course of this thesis effort. I would, also, like to thank my research sponsor, Lt Col Darrin Ott, from the School of Aerospace Medicine for the support provided to me in completing this research. I am also indebted to Dr. Jacky Rosati and the many professionals working with her at the Environmental Protection Agency whose knowledge and expertise were essential to completing the experimental work associated with this project. Special thanks go to Dr. Daniel Felker, Dr. Edward White, and TSgt Carrissa Acosta for their assistance in performing microscopy, conducting statistical analysis, and in developing fluorometric calibration curves, respectively. I am particularly indebted to Capt Casey Cooper and grateful for his outstanding dedication, expertise, and assistance in this endeavor from its beginning to its end. Lastly, I am ever so blessed, thankful, and grateful for the unending support, willful sacrifice, and unconditional love of my wife and son throughout this odyssey, without which this work could not have been completed. Jon E. Black v Table of Contents Page Abstract .............................................................................................................................. iv Acknowledgements ..............................................................................................................v Table of Contents ............................................................................................................... vi List of Figures .................................................................................................................. viii List of Tables ................................................................................................................... viii I. Introduction ......................................................................................................................1 Motivating Factors for Biological Agent Sampling .....................................................1 Basic Model of Airborne Biological Agent Exposure and Impact...............................3 Collection of Airborne Biological Agents ....................................................................4 Primary Air Force Airborne Biological Agent Sampling Equipment ..........................8 Thesis Objectives and Limitations .............................................................................11 II. Literature Review ..........................................................................................................15 Overview ....................................................................................................................15 Selected Cases of Air Sampling for Biological Agents..............................................15 Aerosol Characteristics and Sampling Methods .........................................................19 Virtual Impaction........................................................................................................27 Air Force Fielded High Volume Samplers .................................................................30 Collection Media ........................................................................................................33 Fluorometry ................................................................................................................35 Problem Statement and Summary ..............................................................................36 III. Methodology ...............................................................................................................39 Objective.....................................................................................................................39 Study Design Overview ..............................................................................................40 Aerosol Test Chamber Setup and Layout ...................................................................40 Test Aerosol Generation .............................................................................................41 Equipment Preparation ...............................................................................................44 Particle Concentration Ratio Experimental Data Collection ......................................47 Collection Media Particle Capture and Retention Experimental Data Collection .....52 Fluorometric Calibration Curves ................................................................................56 Microscopic Analysis .................................................................................................57 Data Analysis..............................................................................................................59 IV. Results and Analysis ...................................................................................................61 vi Page XMX Volumetric Flow Rates ....................................................................................61 Virtual Impactor Concentration Ratio as a Function of Particle Size and Secondary Flow Rate....................................................................................................................64