Sensor-based air quality monitoring is growing among community and government-backed densified monitoring networks around the world. Thermo Fisher Scientific has developed and released a sensor-based instrument to meet rising customer demands for “Smart City” and Fence Line monitoring. The Thermo Scientific GM-5000 uses both standard gas and co-location calibrations to provide a precise and robust measuring solution capable of all-weather operation, while building a successful, global user base. This paper presents data from one project in a municipality where 66 units of GM-5000 are deployed to identify pollution sources at grid level for regulators to curb pollution by limiting industrial emissions. The project is a great demonstration of “Smart City” conception empowered by sensor technology and cloud-based big-data analytics.