&EPA
technical BR
Systematic Evaluation of Aggressive Air Sampling for Bacillus anthracis
Spores
Introduction
The ability to accurately measure contamination in the
environment is crucial to reliably assess risk and determine
when reoccupation of spaces may occur. Existing surface
sampling methods (i.e., wipe, swab, sponge stick) may not be
optimum for all situations. The efficacy of existing surface
sampling methods varies widely and contaminant recovery can
be low. These methods may not be effective for all surfaces,
nor can surface sample results be used to infer air
contamination levels. Additional sampling methods, capable of
yielding consistent and reliable data linked to inhalation, are
needed.
AAS involves the use of forced-air equipment such as leaf
blowers to dislodge and reaerosolize particulates, and slow-speed fans to keep the particles
suspended while air samples are collected. Since 1985, AAS has been recommended by EPA for use
in sampling following asbestos remediation; surface sampling is not recommended.1 Aggressive air
sampling has also been used following building decontamination in response to the Amerithrax
incidents of 2001 when it was discovered that reaeresolization of Bacillus anthracis spores from desks,
floors, etc was occurring.2 However, this AAS method has been used as a supplemental method to
surface sampling.
EPA's Homeland Security Research Program
(HSRP) develops products based on scientific
research and technology evaluations. Our
products and expertise are widely used in
preventing, preparing for, and recovering from
public health and environmental emergencies
that arise from terrorist attacks. Our research
and products address biological, radiological,
or chemical contaminants that could affect
indoor areas, outdoor areas, or water
infrastructure. HSRP provides these products,
technical assistance, and expertise to support
EPA's roles and responsibilities under the
National Response Framework, statutory
requirements, and Homeland Security
Presidential Directives.
Aggressive Air Sampling (AAS) Project
Although AAS has been used for supplemental
spore sampling, it has not been rigorously and
systematically tested to support use as a primary
method. As such, EPA is initiating a study to
assess the applicability of AAS to B. anthracis
spore sampling for clearance and
characterization. If AAS is found to be effective
for spore sampling when compared to surface
sampling, it may enable clearance and
characterization with fewer samples than the
current surface sampling methods. Also,
contractors skilled at asbestos sampling using
AAS could be employed during an anthrax
response to increase sampling capability3. Unlike
surface sampling, samples may be directly associated with inhalation risk.
The asbestos aggressive air sampling procedure will be applied to B. anthracis surrogate spores
deposited on to coupons of selected indoor and outdoor surface materials. Varied concentrations of
surrogate spores will be deposited onto target surface materials via aerosolization. The tests will be
-------
conducted in EPA's relative humidity and temperature controlled testing chamber. The efficacy of AAS
compared to surface sampling for spores will be measured as a function of three surface spore
concentrations, deposited on at least three surface types using two dissemination methods3.
OEM and Regions (OSC, On-Scene Coordinator) have requested this evaluation to support potential
use of this method for anthracis spore sampling during remediation. Both OEM and OSCs are
represented on this research team3. A report on this study is expected early 2013.
For additional information, contact Dr. Sang Don Lee, (lee.sangdon@epa.gov)
References:
1. U.S.EPA, 1985 Guidance for the Control of Asbestos-Containing Materials in Buildings. EPA
560/5-85-024.
2. Kelly, Jack. 2004. Anthrax/Ricin Case Histories -Air Sampling (+) for WMD. Presentation, OSC
Readiness. November.
3. Lee, S.D., Mickelsen, L, Mattorano, D. 2011. White Paper for 2012 WARRP S&T Program
Systematic Evaluation of Aggressive Air Sampling for Bacillus anthracis Spores.
January, 2012
EPA/600/S-12/003
------- |