Thanks to Lastmanstanding and Bhoppa. I guess my rather naive question would then be: in a dense ``environment`` like the surface of earth, does that mean that, having all been measured by trillions of particles, do all particles in objects we observe remain permanently decohered...
When a particle decoheres, or its component states get entangled with the ``environment``, surely this is not a final eigenstate. The particle is interacting ( becoming entangled etc) with other particles and systems constantly. Therefore, isn't decoherence a continuous process?