I am not aware of any zone around a hospital.
If the hospital is publicly owned (ie.. some county general hospital) then that probably counts as a public building.
Most hospitals I am aware of around California, are privately held (Kaiser, Sutter, CHW etc...)
you can look at http://codes.lp.findlaw.com/cacode/PEN and do a search on the terms firearm and hospital.
There is nothing that comes up that really pertains.