Predicting particle number concentrations near a highway based on vertical concentration profile

This paper presents vertical profiles of particle number concentration and size distribution near the Interstate 405 Freeway. Based on vertical concentration data, averaged emission factor for total particle number concentration was determined to be 8.3e14 particle−1 vehicle−1 mile−1. A simple analytical solution was obtained by solving the atmospheric diffusion equation and used to predict horizontal profiles of total particle number concentrations. Good agreement was achieved when model results were compared with previously published experimental data (J.Air Waste Manage. Assoc. 52 (2002b) 174–185). Model inputs are traffic, wind, and locations. With the particle emission factors, traffic compositions, and meteorological data, particle number concentrations near freeways can be quantitatively determined using the simple equation achieved in this study.