Researchers estimate that second-hand smoke exposure contributes to nearly 1.7 million deaths worldwide in 2023, according to a study published in The Lancet on Tuesday.

The findings report that more than 2.7 billion people, including about 767 million children aged 0 to 14, were exposed to second-hand smoke in 2023. The study attributes this health burden to tobacco-related disease, noting that there is no safe level of exposure. It estimates 1.66 million premature deaths from second-hand smoke exposure and describes health impacts that include ischemic heart disease and, among children, respiratory infections.

The researchers also examine how exposure occurs, explaining that people near someone smoking inhale both sidestream smoke from burning tobacco and smoke exhaled by the smoker. The sidestream component is described as dominating the air non-smokers breathe and containing higher concentrations of toxic and carcinogenic compounds. While both outlets highlight the scale of exposure and the mortality estimate, they differ mainly in emphasis: one outlet provides additional detail on methods, regional and demographic patterns, and policy calls for stronger tobacco controls in public places and homes.