Study links 1.7 million deaths in 2023 to second‑hand smoke exposure

A research paper published in The Lancet estimates that 1.7 million deaths worldwide in 2023 were linked to second‑hand smoke. The analysis, which combined data from the US National Institutes of Health database PubMed and national population surveys, puts the number of people exposed at 2.7 billion, roughly a third of the global population, including 767 million children aged 0‑14.

Scope of the exposure

The study finds that second‑hand smoke contributed to 1.66 million premature deaths and a range of non‑fatal illnesses. In children, exposure was associated with 5.2 million respiratory‑tract infections and a surge in ischaemic heart disease, a condition caused by insufficient oxygen to the heart muscle.

"Exposure to second-hand smoke is a globally recognised health risk, with no safe level of inhalation," the authors wrote.

People nearby a smoker inhale both the smoke released from the burning cigarette, known as sidestream smoke, and the smoke exhaled by the smoker. The authors note that sidestream smoke contains higher concentrations of toxic and carcinogenic compounds than the smoke inhaled by the smoker themselves.

"The sidestream component, which dominates the air non-smokers breathe, is unfiltered... carrying higher per‑unit concentrations of the toxic and carcinogenic compounds," the paper explained.

While smoking prevalence has fallen since 1990, the absolute number of people exposed has remained steady because of population growth and rising exposure in regions such as Indonesia, Africa and the Middle East. Women, especially in areas where female smoking rates are low, bear a disproportionate share of the burden.

Policy implications

The authors call on governments to tighten tobacco control measures in public venues and private homes. Stronger smoke‑free legislation, higher taxes on tobacco products and public education campaigns could curb exposure, especially in households where women and children spend most of their time.

Health officials warn that without decisive action, the hidden toll of second‑hand smoke will continue to strain health systems and undermine broader public‑health gains achieved through smoking‑cessation programmes.

Future research will likely track how policy changes affect exposure rates, while policymakers may use these findings to justify stricter regulations and targeted interventions in high‑risk regions.