Lidar is a powerful tool for detecting fugitive dust emissions. Here a method using vertical scanning micro pulse lidar (MPL) system to rapidly detect the two-dimensional mass distribution and the temporal variation of fugitive dust plumes in situ is descriped. In this method the backscattering signal from a building in the far field is used as reference to provide a closure condition to lidar equation. The dust plume′s extinction coefficient profiles are determined from the raw MPL signals by inverting the lidar equation. The extinction coefficient profiles are then converted to mass concentration profiles using mass extinction efficiency fator, which is determined by Mie model and simultaneous size distribution measurements. This method quantifies the spatial and temporal variation of the dust′s PM10 and PM2.5 mass concentration when the dust plume passes across the laser light path. In addition, PM10 and PM2.5 emission factors for heavy-duty and light-duty vehicles traveling in the construction field are determined using this method. The mean PM10 emission factors for the heavy-duty and light-duty vehicles are 8.99×103 g/km and 1.75×103 g/km, respectively; the mean PM2.5 emission factors for the heavy-duty and light-duty vehicles are 4.57×102 g/km and 8.91×101 g/km, respectively. This novel method provides an in-situ rapid way to measure PM mass emissions from urban fugitive dust sources.