[en] The concentration pattern of rare-earth elements (REEs) in emissions from oil refineries and newer-model automobiles shows a distortion from the crustal abundance pattern. The REEs arise from the zeolite cracking catalysts used in petroleum refining and emission-control substrates used in automobile catalytic converters, respectively. Ten petroleum cracking catalysts from four countries and 12 catalytic converters from five automobile manufacturers were characterized for their REE content. The cracking catalysts are highly enriched in light REEs, whereas the automobile catalysts are enriched primarily in Ce. Incorporation of zeolite catalysts into refined oil provides new atmospheric elemental signatures for tracing emissions from refineries and oil-fired power plants on a regional scale. Though both have enhanced La/REE ratios, emissions from these two sources can be distinguished by their La/V ratios. Although REE demand by the petroleum industry has dropped considerably in recent years, automobile catalytic converters containing REEs are expected to increase dramatically as more stringent emission regulations are adopted in Europe, Japan and the US