While some response and recovery decisions can be made without knowing the released chemical’s identity, others rely heavily on this information. Chemicals can differ widely regarding physical and chemical properties such as volatility, viscosity, and reactivity. Differences in these properties significantly affect response and recovery processes as unique properties influence impacts such as the penetration of the substance into building materials (some chemicals penetrate some materials more deeply than others) and the persistence of the substance in the environment (some chemicals persist in the environment for much longer time periods than others). The media into which the chemical is released can affect chemical transport, depending on its volatility and persistence. Knowing this information will help guide estimates of dispersal, sampling and analysis strategies, and decontamination techniques. Even properties such as the state of matter of the chemical can play a role in determining appropriate response and recovery activities; for example, gas releases generally have the potential to reach and expose a larger population. Finally, decontamination mechanisms and procedures for different substances vary and translate into vastly different approaches for remediation, which in turn may affect the time required to achieve recovery outcomes. (Available chemical information resources are provided in the Planning, Decision Support, and Modeling Resources for Chemical Incidents section as well as Appendix A.)
The real-time field detector technologies carried by HazMat teams (noted below) can quickly identify many chemicals present in sampled media, on-site. However, the ability of these devices to detect hundreds of chemicals may not be enough to permit immediate identification of the released chemical given that there are tens of thousands of different chemicals in use across the U.S. Moreover, until recently, the agent used in the attack in Salisbury, UK, was not publicly discussed; in such cases, SLTT responders might not have immediate access to the capability to detect or identify the substance used. In addition to HazMat Team on-scene capabilities, EPA’s CBRN CMAD can provide additional screening and sampling support for chemical events, including for CWA. CBRN CMAD equipment includes the Portable High-throughput Integrated Laboratory Identification System (PHILIS), a suite of mobile laboratories with CWA and ICS identification capability, and Airborne Spectral Photometric Environmental Collection Technology (ASPECT), a real-time chemical and radiological detection, infrared and photographic imagery platform. ASPECT consists of a suite of aircraft-mounted sensors and software and is available to assist FSLTT and international agencies supporting hazardous substance response and situational awareness. Further laboratory-based sample analysis can identify a wider spectrum of chemicals but is unlikely to provide substance identification as quickly as needed in an acute release scenario to prevent human health and/or environmental damage. Even when mobile laboratory capabilities are available (including PHILIS, ASPECT, and HazMat team testing equipment), substance identification may be too slow to prevent serious consequences in some scenarios.
If on-site detectors fail, standard tests can classify the chemical substance(s) released into general categories, including auto-reactive, water-reactive, inorganic acid, organic acid, heavy metal, pesticide, cyanide, inorganic oxidizer, and organic oxidizer. Different chemical sampling and characterization approaches will need to be taken depending on the substance itself, whether the release medium is air, soil, ground water, surface water, food, or sediment. EPA provides guidance on available characterization and monitoring technologies via the CLU-IN network.
Further analysis may be conducted by collaborating laboratories to more precisely identify the chemical substances associated with a specific release. Laboratory support for chemical identification testing may come through the Integrated Consortium of Laboratory Networks (ICLN) – a federal partnership between nine departments and agencies – to coordinate laboratory response capabilities during a crisis. The ICLN includes the following networks: DoD Laboratory Network, Environmental Response Laboratory Network, Food Emergency Response Network, Laboratory Response Network, National Animal Health Laboratory Network, National Plant Diagnostic Network, and the Veterinary Laboratory Investigation and Response Network. Again, when laboratory analysis is required for substance identification, the information is unlikely to be provided as quickly as needed in an acute release scenario to prevent human and/or environmental consequences.
Once the presence and concentrations of specific chemicals or classes of chemicals have been established, the hazards associated with these chemicals and their physical and chemical properties can be determined by referring to standard reference sources for data and guidelines. Understanding the chemical hazards faced can go far toward determining appropriate containment and cleanup methods. Available chemical information resources are provided in the Planning, Decision Support, and Modeling Resources for Chemical Incidents section as well as Appendix A.