Colorimetric Monitoring of Trace Toxic Air Pollutants

One of the program areas of interest to the U.S. Environmental Protection Agency (EPA) is the development of rapid, non-invasive monitors to detect exposure to toxic air pollutants at trace (ppt) levels. Of the 356 chemicals listed on the Chemical Emergency Preparedness and Prevention Office¿s List of Extremely Hazardous Substances (Section 302 of the Emergency Planning and Community Right-To-Know Act), more than 40 percent are gases, volatile, liquids, or solids with appreciable vapor pressure under ambient conditions. The Agency for Toxic Substances and Diseases Registry annually releases a list of the ¿Top 20 Hazardous Substances.¿ Six of the substances on the 2001 listing are volatile organic compounds (VOCs); another seven of the hazardous substances are low volatility organic compounds or organic compounds that enter the air via combustion reactions. EPA¿s Environmental Technology Initiative has identified the monitoring of VOCs as a critical need. ChemSensing, Inc., possesses a unique chemical detection technology in which colorimetric changes in an array of dyes constitute a signal much like that generated by the mammalian olfaction system; each dye is a cross-responsive sensor. This technology has been dubbed SmellSeeing¿. This Phase I research project is designed to evaluate the sensitivity, specificity, and reproducibility of the colorimetric cross-reactive sensor when used to monitor exposure to hazardous substances. Fifteen compounds defined as hazardous in the Clean Air Act, reflecting a range of chemical classes, have been selected to pursue trace level analysis via SmellSeeing¿. Color difference maps (¿fingerprint patterns¿) will be determined for the target compounds. ChemSensing, Inc., aims to integrate the SmellSeeing¿ technology into an inexpensive, portable monitor for real-time detection, with ppt sensitivity, of hazardous substances¿the SmellCamera¿. This work will result in a device for surveillance and early recognition of these compounds in the air, thereby reducing exposure and preventing adverse environmental and human health effects as a result of early detection.