A distributed sensor system comprising: a plurality of spatially distributed base units in communication with a data network, each base unit comprising a controller and one or more sensor modules, each sensor module comprising a sensor configured to measure an air quality parameter, the controller in each base unit being configured to transmit raw sensor data associated with each of the sensor modules over the data network, the raw sensor data for a sensor module being identified by a sensor identifier uniquely identifying a sensor in a sensor module in a base unit and a board identifier uniquely identifying the base unit in the system; and a central server in communication with the data network, the central server comprising a data processor and one or more databases (106; 108), the central server configured to receive raw sensor data from the plurality of base units and to store the raw sensor data in a database (106; 108), wherein the central server comprises a calibration data database and a sensor data database, the sensor data database configured for storing the raw sensor data where each entry of the raw sensor data is associated with a sensor identifier and a board identifier, the calibration data database configured for storing calibration data for sensors in the sensor modules of the base units where each entry of the calibration data is associated with a sensor in a sensor module in a base unit as identified by a sensor identifier and a board identifier, the calibration data associated with each sensor includes at least a gain correction value and an offset correction value for the respective sensor, and wherein the central server is configured to generate calibrated sensor data for a first sensor using the raw sensor data stored in the sensor data database associated with the first sensor and using the calibration data stored in the calibration data database associated with the first sensor, the raw sensor data and the calibration data associated with the first sensor being identified in the sensor data database and the calibration data database, respectively, by the same sensor identifier and the same board identifier. a plurality of spatially distributed base units in communication with a data network, each base unit comprising a controller and one or more sensor modules, each sensor module comprising a sensor configured to measure an air quality parameter, the controller in each base unit being configured to transmit raw sensor data associated with each of the sensor modules over the data network, the raw sensor data for a sensor module being identified by a sensor identifier uniquely identifying a sensor in a sensor module in a base unit and a board identifier uniquely identifying the base unit in the system; and a central server in communication with the data network, the central server comprising a data processor and one or more databases (106; 108), the central server configured to receive raw sensor data from the plurality of base units and to store the raw sensor data in a database (106; 108), wherein the central server comprises a calibration data database and a sensor data database, the sensor data database configured for storing the raw sensor data where each entry of the raw sensor data is associated with a sensor identifier and a board identifier, the calibration data database configured for storing calibration data for sensors in the sensor modules of the base units where each entry of the calibration data is associated with a sensor in a sensor module in a base unit as identified by a sensor identifier and a board identifier, the calibration data associated with each sensor includes at least a gain correction value and an offset correction value for the respective sensor, and wherein the central server is configured to generate calibrated sensor data for a first sensor using the raw sensor data stored in the sensor data database associated with the first sensor and using the calibration data stored in the calibration data database associated with the first sensor, the raw sensor data and the calibration data associated with the first sensor being identified in the sensor data database and the calibration data database, respectively, by the same sensor identifier and the same board identifier.