An estimated 1.7 million people died in 2023 due to exposure to secondhand smoke, or tobacco smoke produced by other people.
According to a study, more than 2.7 billion people worldwide were exposed to secondhand smoke, including around 767 million children aged zero to 14.
Among children, secondhand smoke exposure was linked to 5.2 million cases of respiratory tract infections in 2023.
Researchers said there is no safe level of exposure to secondhand smoke, as it contains toxic and carcinogenic, or cancer-causing, chemicals.
Although the global number of smokers has declined since 1990, exposure to secondhand smoke remains high due to population growth and rising smoking rates in some parts of Africa and the Middle East.
The study also found that women were more heavily affected, particularly in areas where smoking prevalence among women is low.
Researchers are calling on governments to strengthen tobacco-control policies in public spaces and homes to protect children and women from the harmful effects of secondhand smoke.