Adjustable sensor or sensor network to selectively enhance identification of select chemical species

An environmental control system (ECS) having contaminants in supply air that flows into an environment includes an outside air contaminant component that senses contaminants in outside air, wherein the outside air contaminant component is upstream of the environment, A recirculated air contaminant component is provided and that senses contaminants in recirculated air supplied by the environment, wherein the recirculated air contaminant component is downstream of the environment. A voltage supply provides a non-linear variable voltage to at least one of the components. A controller is in communication with the components and the voltage supply; wherein, upon a measured resistance, from at least one of the components, that exceeds a threshold, the controller varies at least one of an outside air flow and a recirculated air flow in the ECS.