Numerous cases of respiratory disorders reported in auto, machining and even some food processing plants have caused researchers to take a closer look at the potential dangers of exposure to a variety of oil mists.  Oil mist behavior is determined, in part, by its semi-volatile nature but can be controlled  by enclosing the process and ventilating the enclosure to air filtration equipment that captures and retains the mist droplets. 

Controlling mineral oil mist is difficult because its constituents are semi-volatile.  Thus, they partition back and forth between vapor and droplet phases, depending on the makeup of the liquid and on environmental parameters such as temperature.  Hydrocarbon vapors stripped from filters used to collect mineral oil mist can have concentrations in the mg/m³ range, several orders of magnitude higher than the outlet droplet concentrations.  As the air stream from the mist collector cools, the vapor can condense on cool surfaces to coat them with oil or can even condense in the air to form additional mist.  This issue is also relevant to mist measurement methods, because sampling methods that use filters are subject to sample evaporation.  Thus, effective control and measurement of mineral oil mist is particularly difficult and should consider the entire process, not just collection of the droplets alone.