The Lawrence Livermore Laboratory program to evalute the trace elements in stack emissions from coal-fired power plants is
described. Stack sampling and analysis of fly ash at modern, western U. S. power plants is discussed. Scanning-electron-microscope
techniques are shown to be essential for accurate sizing of stack particles sampled with cascade impactors. Particle-size
distributions for volatile and nonvolatile trace elements are reported. Comparisons show that the trace elemet enrichment
factors of western and eastern U. S. coal-fired power plants are significantly different.