According to a report by the Centers for Disease Control and Prevention (CDC), 21% of US adults used what they term ‘tobacco products’ in 2019, which includes e-cigarettes (whether or not they contain nicotine) but not medicinal nicotine products. Among tobacco product users, 81% reported using combustible products (e.g. cigarettes) and almost 20% reported using two or more tobacco products concurrently. The highest rates of tobacco use were found among adult males under 65-years-old. E-cigarettes were most commonly used by adults aged between 18 and 24.