Electrostatic charge leakage What are the ways electrostatic charged objects leak charge in humid conditions?
Can airborne particles pick up charge by contact, then be repelled hence removing charge? If so would it be a significant factor?
 A: There are two ways charge can leak in humid air. I'll give a basic description here, but I encourage you to Google around the area as you'll find lots of papers reporting measurements of conductivity of humid air and charge leakage in humid air.
The first leakage mechanism is that in the presence of water vapour virtually all materials have an adsorbed layer of water on their surface, and if this water is thick enough charge will conduct through it just as charge conducts through bulk water. See for example this paper, though note it's behind a paywall. Hygroscopic and polar materials adsorb water most easily, while low energy and non-polar surfaces like PTFE do not significantly adsorb water.
The second mechanism is that the conductivity of air increases with humidity. See for example this paper: there's no special significance to this paper other than it was the first Google found for me. The conductivity must be due to charged particles in the air, but I'm not sure it's understood what these particles are. My guess would be dust or pollen. It would be interesting to measure the conductivity of filtered air compared to unfiltered air, but I couldn't find any papers describing this. I'm also not sure why the conductivity increases with increasing humidity. I would guess that water molecules adsorbed onto the charged particles stabilise them in some way.
A: One expalanation is the following :

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*Polarity of water molecules in humid air :

Humid air consists of a percentage of water molecules , water molecules are polar ,and why is that ? Well a molecule consists of chemical bonds between between two atoms or more , this chemical bond is guaranteed via a share of electrons , that is to say a number of electrons is contributed by each of the atoms constituting the molecule , in the water molecule , and in many other cases, one atom tends to attract the shared electrons more to its side , in the water molecule case the oxygen molecule has much important force acting on the shared electrons then the two hydrogen atoms have on the same electrons , so these electrons spend much more time closer to the side of the oxygen , here a difference in polarity is created , the molecule becomes polar. Now comes the part where an object that has a static charge is surrounded by humid air ( could be non conductor or conductor held by a non conductor) , as we said , water molecules in air are polar so the excess of electrons that produces the static charge on the object is attracted to the positive side of the water molecules( as we said they are polar) that hover near the surface of the object , this results in electrons "jumping" to the water molecules , same thing goes for the positive charged object as electrons on the negative side of the water molecules are attracted to the positive charge on the object (lack of electrons).
