A major problem facing defensive forces exposed to chemical agents is the lack of an accurate method for detecting the active life remaining in filters. Methods available to-date are slow and involve fairly expensive equipment which require more than casual familarity with chemical instrumentation. In addition, much of the present day, instrumentation that would be useable for such measurements is fragile and thus, unsuitable for field usage. A monitor, that would measure the residual filter life, to be built-under this contract would be very small and inexpensive. These sensors would be expendable and could be built into the fiber bed. They would be very sturdy and require little power to operate.