Ultra-fine particles are increasingly being recognized as a potential threat to health. Aerosols in workplace environments may come from a wide variety of sources, depending on the type of activity and processes taking place. To quantify the level of risks associated with engineered nanomaterials, research needs to first quantify the level of nanoparticles' exposure encountered in different construction activities. Therefore, the objective of this study is to evaluate the potential inhalation exposure risk associated with Hot-Mix Asphalt (HMA) and concrete preparation activities in the laboratory. To achieve this objective, the number concentration, size distribution, surface area, and mass concentration were measured for different activities including dry mixing, wet mixing, pouring, and compaction in an asphalt and concrete laboratory using a Scanning Mobility Particle Sizer (SMPS). In addition, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) characterized the morphology, shape, and measure the primary size distribution of the particles. The estimates obtained by TEM analysis in the workplace study were similar to the estimates obtained by calculations using SMPS for the experimental study.