1. Nanoparticle characterization

1.1 Definitions

An aerosol is defined as a suspension in a gas (usually air) of solid or liquid particles with negligible falling velocity. In air and under near-ambient conditions (20°C and 101 kPa), this corresponds to particles smaller than around 100 µm.

Some aerosols may be composed of ultrafine particles (UFP) or nanoparticles characterized by their three external dimensions of less than 100 nm. Because of their small size and high concentration, nanoparticles have a strong tendency to agglomerate, forming agglomerates or aggregates of nanometric particles, like soot particles or welding fumes.