Soft selection - surface test
This is probably not possible, but why not ask?  Cool
Sorry if this was asked before 

So imagine youdo some particles selection (in whatever way with property test, or surface test), and send it to next event (with wind, or whatever). 
So we have first half of particles left in the first event (static), and the second half send to next event (with some force). 
How make second particles behave like soft selection, so, on some wind is affecting more, and on some others (that are closer to the particles in first event), less? 

Maybe introducing something like sub-event where soft selected particles are sent, and being told to gradually (by distance) be affected by the wind. 

I guess, workaround would be making few selections, and sending one by one into separate event with stronger and stronger wind.
Impossible, the test is a Boolean type.
Make a box or else geo object. The particles initially have to be in the box' volume. Animate the box away from your wind source, so that your particles will leave the box' volume. Test the paricles with "surface test -> volume (outside)" and send them to the next event where your wind affects the particles.
Now your particles become smoothly affected by the wind. How smooth this transition would be depends on the speed of your box animation.

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