Complex sentence: Lead smelting by the Doe Run Company is no longer operating and under a shutdown process, it was a major industry in Herculaneum until it's closure due to inability to match increased EPA regulations due to environmental and health effects.
Split into simpler sentences: Lead smelting by the Doe Run Company is no longer operating and under a shutdown process. It was a major industry in Herculaneum until its closure due to inability to match increased EPA regulations due to environmental and health effects.