Schauer GL, et al. - Via performing internet panel survey among US adults aged ≥ 18 years (n = 4,088) in June-July 2018, researchers sought to determine the attitudes about public marijuana smoking, perceptions of harm from marijuana secondhand smoke (SHS), and self-reported marijuana SHS exposure. Past-week marijuana SHS exposure, in indoor and/or outdoor public areas, was reported by 27.4% (95% CI: 25.7, 29.1) of adults; the exposure was more common among younger adults, blacks, Hispanics, those in the Northeast or West, and current marijuana and/or tobacco users. A majority of the US adults believe marijuana SHS as harmful and most of them oppose public marijuana smoking.