An idea that may help control exhausted dust.

[John Isgren]

John, is it a matter of electrical charge?
Might an ionizer prior to exiting the duct be helpful?

Charge might be a factor. The bigger issue is the water droplet pushes air in front of it and that air pushes the dust particle out of the way.

[Bill Jobe]

Suppose an emulsifying agent, such as Dawn dishwashing liquid were added to the water by using a fertilizer jug prior to reaching the dust?

[George Yetka]

Not to change the topic but couldn't you just use a paper filter in an open window? As the air is sucked out of the shop a vacuum will be created an open window/louver with an air filter would be an easier source of makeup then other cracks and crevices that may otherwise bring in the makeup.
It would be cheaper and easier to maintain than a wet system

[Brice Rogers]

I use a separator AND exhaust outside. The separator is a Thien baffle. I used the metal center section of a Harbor Fright DC for the circular section of the thien. The whole thing sits on top of a galvanized metal trash can. I haven't done any exhaustive tests to measure its efficiency but after emptying about 10 trash barrels of the separated dust and chips, I don't see much, if any, sawdust or shavings accumulating outside. If I stuff the intake hose into a big pile of shavings it will temporarily overload the thien baffle and I see a small amount of dust going outside. But even then, the vast majority of the sawdust still ends up in the trashcan.
.
If I used an Oneida dust deputy instead of my home-made Thien, I might get even greater collection efficiency and even less dust going outside.

I don't have any concern that the exhausted dust that gets sucked back into my workshop is of any significance. But, I do close the service door that is on the same wall as the exhaust.