Fugitive Particulate Matter Emissions to the Atmosphere from Tracked and Wheeled Vehicles in a Desert Region by Hybrid-Optical Remote Sensing

A hybrid-optical remote sensing (hybrid-ORS) method was developed to quantify mass emission factors (EFs) for fugitive particulate matter with aerodynamic diameters ≤ 10 μm (PM 10 ) and ≤ 2.5 μm (PM 2.5 ). In-situ range-resolved extinction coefficient and concurrent point measurements of PM 10 and PM 2.5 mass concentrations are used to quantify two-dimensional (2-D) PM 10 and PM 2.5 mass concentration profiles. Integration of each 2-D mass concentration profile with wind data, event duration, and source type provides the corresponding fugitive PM 10 and PM 2.5 EFs. This method was used to quantify EFs for fugitive PM 10 and PM 2.5 emitted from tracked and wheeled vehicles travelling on unpaved roads in a desert region. The EFs for tracked vehicles ranged from 206 g/km to 1,738 g/km for PM 10 and from 78 g/km to 684 g/km for PM 2.5 , depending on vehicle speed and vehicle type. The EFs for the wheeled vehicle ranged from 223 g/km to 4,339 g/km for PM 10 and from 44 g/km to 1,627 g/km for PM 2.5. Field implementation of the hybrid-ORS method demonstrates that the method can rapidly capture multiple profiles of the PM plumes and is well suited for improved quantification of fugitive PM EFs from vehicles traveling on unpaved roads.