Wind direction in Japan has been northbound for days, and this pattern will continue until Sunday

A gracious trajectory for the rest of Asia

Can't embed this, you can view it here.  Select 'Japan wide streamlines'

If radiation readings have been down in your area lately, this is primarily why.  I'm sure tepco will promptly and enthusiastically inform us when dispersion volumes from the plant significantly drop off - offering a solid reason to start feeling better about potential exposures.

You can view their simplified dispersion model of radioactive emissions here.  Select 'Japan wide emission dispersion'