A particle is defined as a small object that behaves as a whole
unit in terms of its transport and properties. It is further
classified according to size: in terms of diameter, fine particles
cover a range between 100 and 2500 nanometer, while ultrafine
particles, on the other hand, are sized between 1 and 100
nanometers. Similar to ultrafine particles, nanoparticles are sized
between 1 and 100 nanometers.