What is an Intervention?

I recently had an academic refer to my projects of putting poetry text in unexpected places or on unusual materials as an “intervention.” Being from New Jersey, I think of an intervention as something you do when you realize a friend or family member is an addict–confront him or her and whisk the person off to rehab.
So I don’t like the word as applied to art. In Edie Tsong’s citywide project of Snow Poems on windows throughout Santa Fe is the text an “intervention” in the urbanscape? Why not call it a snack? Or an accessory?
Of course these texts should make the passer-by pause. Maybe the intervention is with our usual frame of mind. I usually say “install.” I think of everything I’ve done–from a laundry line in pinon and juniper wilderness to the Poetry Posts at Community College campus as installation. It might be impermanent. Or changeable. Irritating. Pretty. Something on the wind.
But I don’t feel the earth needs my intervention.