In order to maintain a level of security for populated buildings and protect critical infrastructure, a continuous air monitoring system should be employed in the air handling system for that building. Many possible terrorist threats have been identified by the Department of Homeland Security, among which is the use of Chemical Warfare Agents (CWAs) or Toxic Industrial Chemicals (TICs) to either harm building occupants or cause business disruptions. Initial schemes for CWA or TIC detection used monitoring technologies which have been found to lack the sensitivity or selectivity to make them useful against multiple chemical threat sources along with interferents such as common solvents and cleaners. These interferents often result in a large number of false alarms which are costly and reduce the overall effectiveness of the monitoring system. A continuous air analyzer should detect multiple agents very quickly with no, or extremely infrequent, false alarms to enhance the utility and security protection of these ambient air monitors for homeland security applications.
Environmental Air Monitoring Challenges:
To avoid the high false alarm rate and maintain the capability of monitoring multiple types of CWA and TIC, another method must be used, one which has very high specificity while maintaining high sensitivity. The method of choice is Fourier transform infrared spectroscopy (FTIR) which is the basis for the AIRGARD® Plus air analyzer. Even though common chemical families (e.g., ketones, alcohols, amines) have similar regions of infrared absorption, the detailed spectra of each have subtle but important differences. By combining the sensitivity of FTIR with the specificity of individual infrared spectra, a system can monitor CWA and TIC levels well below the U.S. EPA Acute Exposure Guideline Level 210 (AEGL210) limits.