A HAZMAT monitoring system detects a plurality of different hazardous materials and includes first and second pluralities of RSIs. Each RSI of the first plurality forms a node in a first wireless sensor network and is associated with a mobile container and with at least one sensor that is configured to acquire data for detecting a first hazardous material. Each RSI further is configured to receive the sensor data and wirelessly transmit, over the first wireless sensor network, data relating to the received sensor data pertaining to the detection of the first hazardous material. Each RSI of the second plurality is similarly associated and configured. Communications within a respective wireless sensor network do not result in communications within the another wireless sensor network. A gateway is configured to independently communicate with each respective wireless sensor network.