Rare earth elements unintentionally released from global industrial activities.

Exposure to rare earth elements (REY) in the environment can lead to adverse effects on human health. Industrial activities unintentionally produce fly ash, and a small fraction of fly ash that remains uncaptured by air pollution control devices can enter the atmosphere and contribute as a primary source of airborne fine particle matter (PM). The occurrence of REY in industrial sourced fine PM affects the environment and human health. There is relatively minimal information regarding the human health hazards and biological effects of REY in fine PM produced during industrial activities, especially for non-occupational people. In addition, REY are powerful source-specific tracers for airborne PM from industries. Therefore, relevant research on REY in fine PM from industrial processes not only contributes to understanding and preventing environmental pollution but can also provide basic data for reducing human exposure. This paper provides an overview of the research status and latest advances in various industrial processes, especially their distribution characteristics, influencing factors, tracer application, and biological effects of REY in fine PM from coal-fired power plants. We also suggest future research directions in light of existing problems.