1 22 May 2012
Voluntary Consensus Standards for Chemical Detectors
Pamela M. Chu
a
and Charles E. Laljer
b
a
National Institute of Standards and Technology, Gaithersburg, MD 20899
b
MITRE Corp., San Antonio, TX 78227
1.0 Introduction
In the event of a toxic chemical release, either through an act of terrorism, industrial accident, or natural
disaster, effective incident management requires accurate real-time chemical analysis of the materials in
question. To help ensure that proper evacuation and decontamination procedures can be initiated, it is
critical for first responders and soldiers to have chemical detection equipment which enables the
identification of the chemical hazard, the threat level, and the boundaries of the contaminated area.
Furthermore, the detection equipment must operate reliably and accurately, and the users must have
confidence in the equipment. Correctly identifying and quantifying hazardous chemical vapors in the
field is challenging; there are hundreds of industrial chemicals that are toxic at low concentrations from
parts-per-million to sub parts-per-billion concentrations.
1,2
Environmental conditions and commonly
occurring benign chemicals can impact the measurement of vapors of interest by either masking the
presence of a toxic material (false negative) or, conversely, by triggering an alarm when toxic materials
are not present (false positive). These false negative alarms expose people to significant health risks
while false positive alarms cause user loss of confidence in the equipment and unnecessary and costly
evacuations.
With 207 chemical detectors listed in the Guide for the Selection of Chemical Detection Equipment for
Emergency First Responders,
3
there are many options for detection equipment purchasers. For
example, there are up to 10 different types of chemical measurement technologies used in point
detectors for chemical warfare agents (CWA), toxic industrial chemicals (TIC), and toxic industrial
materials (TIM). While the diversity of equipment is advantageous, it also presents a significant
challenge; it is difficult to directly compare the instrument capabilities and to assess which detector best
suits an organization’s specific priorities. It is important to emphasize that the product summaries and
evaluations in the Guide are based solely on vendor-supplied information and there is no process to
verify that the equipment will perform as advertised. Several recent studies suggest that the goals of
clear, concise purchasing information to first responders are not currently met.
4-6
Additionally, a 2011
MITRE Corporation study for the Department of Homeland Security Science and Technology Directorate
(DHS S&T), Chemical and Biological Division (CBD) identified 339 different sensors. The study found that
commensurable comparisons of chemical detectors were difficult due to the lack of independent data
that could be correlated (false alarm rates, sensitivity, reliability, etc.) from the various vendors. To help
guarantee the safety of the public, incident response personnel, and warfighters, it is critical that
chemical detectors function as advertised, meet key performance requirements, and that users have
complete confidence that the equipment provides accurate and reliable information.
There are three primary groups to consider during the development of chemical detection performance
standards, specifically: 1) Responders must have confidence in chemical detectors that meet the
standard and are able to compare generated data; 2) Industry requires an equitable means to
demonstrate that products meet responders’ needs; and 3) Vendors require a means to test new
technologies and compare capabilities. In similar situations, where underperforming products are
potentially dangerous or place people at risk, a standards-based conformity assessment process can
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