A new study published on Tuesday, September 8, in The Lancet reveals that about 2.7 billion people worldwide are exposed to secondhand smoke. This exposure, the study estimates, caused 1.66 million deaths in 2023—nearly a fifth of the 8 million total deaths linked to tobacco that year. The research, which reviewed all relevant studies published on PubMed from 2010 to 2025, analyzed data from 204 countries over more than 30 years. It aimed to understand how common secondhand smoke exposure is and how much it contributes to illness and early death, broken down by age and sex. In 2023, the study found that 767 million children under the age of 15 were exposed to secondhand smoke. This exposure is linked to significant health impacts, including 5.16 million cases of respiratory tract infections among children that year. Globally, secondhand smoke exposure is associated with 44.8 million years of healthy life lost, primarily due to ischemic heart disease—a condition where blood flow to the heart is restricted. Secondhand smoke, which includes the smoke exhaled by smokers and the smoke from the burning end of a cigarette, increases the risk of several serious health conditions, including heart disease, respiratory issues, and metabolic disorders. Children are especially at risk because their bodies are still developing, and their smaller airways are more easily affected by harmful particles in smoke. While the study notes that global smoking rates have dropped by 22% since 1990, the number of people exposed to secondhand smoke has remained roughly the same. In some regions, such as sub-Saharan Africa, North Africa, and the Middle East, exposure has even increased. The researchers stress the importance of stronger tobacco control policies to protect vulnerable groups, such as women and children, in both public spaces and at home. They argue that reducing secondhand smoke exposure is critical to improving global health outcomes.