Abstract: A method of measuring an environmental contaminant includes the steps of dividing a target environment into a plurality of spaces, placing a monitor in each space, uploading device data from each monitor, and processing the device data to determine a level of environmental contamination within each space. Each monitor is configured to measure a level of an environmental contaminant within the space for a sample period. A radon monitor includes a radon sensor configured to detect radon decay events, an environmental sensor configured to measure an ambient condition of air surrounding the radon sensor, a processor configured to record device data including a count of a number of radon decay events and the ambient conditions, and a communication means for transmitting the device data. A system includes a plurality of monitors, a receiving device for receive device data from each monitor, and a cloud computer to process the device data.