Warning: this episode contains descriptions of a mental health crisis and violence. This Election Day, recreational marijuana could become legal across more than half of the United States. But as more Americans consume more potent forms of the drug more often, a Times investigation has revealed that some of the heaviest users are experiencing serious and unexpected harms to their health. Megan Twohey, an investigative reporter for The Times, explains what she found. Guest: Megan Twohey, an investigative reporter for The New York Times.