Abstract: The present disclosure relates generally to air quality and occupancy monitoring (AQOM) system that include at least one AQOM monitoring device and a portal configured to communicate with the monitoring devices. The monitoring devices have sensors that collect and send environmental data to the portal. The portal, in turn, allows a user to access, review, analyze, and/or download the environmental data collected. In some embodiments of the AQOM monitoring device, the sensors are configured on an interchangeable component allowing for modularity of the device.