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ABSTRACT
The Wide Area Demonstration (WAD) was a field exercise conducted under the U.S. EPA’s Analysis of Coastal Operational Resiliency program, in conjunction with the U.S. Department of Homeland Security and the U.S. Coast Guard. The purpose of the WAD was to operationalize at field scale aspects of remediation activities that would occur following an outdoor release of Bacillus anthracis spores, including sampling and analysis, decontamination, data management, and waste management. The WAD was conducted in May 2022 at Fort Walker (formerly known as Fort A.P. Hill) and utilized Bacillus atrophaeus as a benign simulant for B. anthracis. B. atrophaeus spores were inoculated onto the study area at the beginning of the study, and air samples were collected daily during each of the different phases of the WAD using Dry Filter Units (DFUs). Ten DFU air samplers were placed at the perimeter of the study area to collect bioaerosols onto two parallel 47-mm diameter polyester felt filters, which were then subsequently analyzed in a microbiological laboratory for the quantification of B. atrophaeus. The study demonstrated the use of DFUs as a rugged and robust bioaerosol collection device. The results indicated that the highest B. atrophaeus spore air concentrations (up to ~ 5 colony forming units/m3) occurred at the beginning of the demonstration (e.g. during inoculation and characterization sampling phases) and generally downwind from the test site, suggesting transport of the spores was occurring from the study area. Very few B. atrophaeus spores were detected in the air after several weeks and following decontamination of exterior surfaces, thus providing an indication of the site decontamination procedures’ effectiveness. No B. atrophaeus spores were detected in any of the blank or background samples.
Implications: Following an incident involving a release of Bacillus anthracis spores or other biological threat agent into the outdoor environment, understanding the factors that may affect the bioagent’s fate and transport can help predict viable contaminant spread via the ambient air. This paper provides scientific data for the first time on ambient air concentrations of bacterial spores over time and location during different phases of a field test in which Bacillus atrophaeus (surrogate for B. anthracis) spores were released outdoors as part of a full-scale study on sampling and decontamination in an urban environment. This study advances the knowledge related to the fate and transport of bacterial spores (such as those causing anthrax disease) as an aerosol in the outdoor environment over the course of three weeks in a mock urban environment and has exposure and health risk implications. The highest spore air concentrations occurred at the beginning of the study (e.g. during inoculation of surfaces and characterization sampling), and in the downwind direction, but diminished over time; few B. atrophaeus spores were detected in the air after several weeks and following decontamination. Therefore, in an actual incident, potential reaerosolization of the microorganism and subsequent transport in the air during surface sampling and remediation efforts should be considered for determining exclusion zone locations and estimating potential risk to neighboring communities. The data also provide evidence suggesting that the large-scale decontamination of outdoor surfaces may reduce air concentrations of the bioagent, which is important since exposure of B. anthracis via inhalation is a primary concern.
Acknowledgment
The authors would like to thank the following people for their support and assistance throughout the project:
JTI: Tim Chamberlain and Jonathan Sawyer helped with sample kit preparation and Brian Ford, Lesley Mendez-Sandoval, and Rachael Baartmans processed the samples and recorded the data.
EPA Office of Research and Development: Lukas Oudejans, John Archer, and Paul Lemieux.
U.S. EPA personnel DFU sampling teams: Duane Newell, Ray Ledbetter, Jeff Szabo, Elise Jakabhazy.
Consolidated Safety Services: Neil Daniel and Anne Busher.
DHS: Don Bansleben and Andrea Wiggins; Jane Tang (DHS contractor).
USCG: Emile Benard.
Weston Solutions: Lawrence Campagna.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Data availability statement
In general U.S. EPA datasets may be found here: https://catalog.data.gov/organization/epa-gov. And specifically for this project, underlying raw data (e.g., microbiological plate counts) may be found here once the journal article is published: https://doi.org/10.23719/1529833.
Supplementary material
Supplemental data for this article can be accessed online at https://doi.org/10.1080/10962247.2024.2359122
Additional information
Funding
Notes on contributors
Joseph P. Wood
Joseph P. Wood is a Senior Research Engineer with U.S. EPA’s Office of Research and Development, in the Homeland Security Research Program. His research primarily involves the testing, evaluation, and development of technologies that can be used to decontaminate or sterilize surfaces and environmental matrices contaminated with biological agents such as Bacillus anthracis spores and biotoxins such as ricin. He also investigates related areas such as the fate/transport and sampling of bioagents and biotoxins; treatment and disposal of waste materials; and engineering aspects of decontamination processes.
Erin Silvestri
Erin Silvestri is the Branch Supervisor for the Materials Management and Oil Spill Branch, within the U.S. Environmental Protection Agency’s (EPA), Center for Environmental Solutions and Emergency Response, Homeland Security and Materials Management Division (HSMMD). Prior to joining MMOSB, she has 16 years previous experience supporting EPA’s Homeland Security Research Program as both an environmental health scientist and biologist, with recent research focusing on development of sampling protocols for pathogens. She holds a Master’s in Public Health in Occupational and Environmental Epidemiology from the University of Michigan School of Public Health.
Michael Pirhalla
Michael Pirhalla is a Physical Scientist in EPA’s Office of Research and Development, Center for Environmental Solutions and Emergency Response. He holds a PhD in atmospheric sciences from North Carolina State University. His research activities focus on the flow and dispersion of airborne contaminants as well as improving sampling and analysis methods for surfaces potentially contaminated with biological agents.
Shannon D. Serre
Shannon D. Serre is a Chemical Engineer with the EPA’s Office of Emergency Management working in the CBRN Consequence Management Advisory Division. He is focused on the response and recovery from a chemical, biological or radiological incident. He has led several field scale projects including the AnCOR Wide Area Demonstration.
M. Worth Calfee
M. Worth Calfee is Senior Research Microbiologist with U.S. EPA’s Homeland Security and Materials Management Division within the Center for Environmental Solutions and Emergency Response. He has over 25 years of research experience with 15 years at the U.S. EPA in researching decontamination and consequence management of Chemical, Biological, and Radiological (CBR) agents. Dr. Calfee earned his Ph.D. in 2007 from East Carolina University, where he studied the impacts of anthropogenic disturbance on estuarine microbial communities.
Katrina McConkey
Katrina McConkey is a Physical Scientist with EPA’s Chemical, Biological, Radiological, Nuclear Consequence Management Advisory Division (CBRN CMAD). She has 20 years of experience in emergency response support and research. With expertise spanning from CBRN tactical and operational guidance to laboratory testing, field studies, and exercises, Katrina has provided subject matter expertise to several U.S. federal agencies, including the EPA, DoD, DHS, and law enforcement. Ms. McConkey has supported several interagency research initiatives relating to the characterization and cleanup of contaminated sites.
Timothy Boe
Timothy Boe is a Geographer with the U.S. EPA’s ORD. Timothy’s work primarily focuses on response and cleanup issues following chemical, biological, radiological and nuclear (CBRN) incidents. He has also been developing computer-based decision support tools to aid decision makers in responding to wide-area contamination incidents. Before joining the EPA, Timothy worked as an Oak Ridge Institute for Science and Education Fellow where he conducted research on wide area CBRN remediation. Timothy has an M.S. and a B.S. in Applied Science from Arkansas Tech University.
Mariela Monge
Mariela Monge is a Microbiologist with over ten years of EPA research, commercial environmental testing, and university research laboratories; with five years of EPA research related to microbiological research and development for decontamination, remediation, and optimization of sampling methods for bacteriophages, eukaryotic viruses, and bacteria. She received her Bachelor’s in Science at the University of South Carolina.
Denise Aslett
Denise Aslett, Ph.D., is a Senior Research Microbiologist with Jacobs Technology. She has over thirteen years of microbiological research experience with eight years supporting the U.S. EPA’s research regarding decontamination and clean-up following a wide area biological contamination incident. Her work has focused on surface and environmental sampling and analysis methodologies, fate and transport studies, detection of target organisms in complex matrices using molecular methods, and surface disinfection of emerging pathogens, including viruses and bacteria.
Ahmed Abdel-Hady
Ahmed Abdel-Hady is a Senior Microbiologist at Jacobs Technology, Inc. Mr. Abdel-Hady has been a research scientist at JTI for 8 years. His research interests have included remediation strategies in various environments and the fate and transport of organisms following a potential bioterrorism incident, disinfection strategies for emerging pathogens, optimization of sample analysis, and novel sample collection methodologies.