The soft emission of {TAIL ~ electrons} from the beta emitting gas can not penetrate the glass wall of the microspheres, thereby constituting {HEAD ~ no radiation hazard} 
The soft emission of { TAIL ~ electrons } from the beta emitting gas can not penetrate the glass wall of the microspheres , thereby constituting { HEAD ~ no radiation hazard }
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD