A study based on U.S. Census and Department of Transportation traffic data found that nearly one-fifth of the U.S. population lives near a high-volume road where pollution levels are typically elevated from vehicle exhaust. The evolution of particle size distribution is too fast at a near-road location to be measured by a typical particle size classifier. Yue has two goals in her investigation. First she will measure aerodynamic particle size distribution and examine evolution of mass concentration. Second she will measure mobility particle size distribution using TSI FMPS, which has a faster response than regular sizing instrument of SMPS, along with the aerodynamic particle size distribution measurement by MSP QCM MOUDI.