Some transformation to derivatives may occur in the lung and, as with transformations in the liver, the derivatives produced may be either more toxic or less toxic. Assessment of these transformations must be done on a case by case basis. Vapour Vapours are the gaseous form of substances which are normally in solid or liquid form at the existing temperature and pressure. Vapours are in equilibrium with the solids or liquids from which they originate. The equilibrium changes with changes in temperature and pressure.
Vaporization increases with increase in temperature or with decrease in pressure.
Usually the size of the particles in an aerosol is sufficiently small to allow them to remain suspended for long enough to be widely dispersed. Amongst aerosols, a distinction is made between dusts, fumes, smokes, and mists and fogs. The nature of any dust is highly dependent on the process that produced it. Thus, altering the process may alter, for better or worse, the health hazard to workers and others exposed to the dust. Fumes Fumes are solid particles formed by condensation from the gaseous or vapour phase.