Key takeaways:

• Around 2.71 billion people worldwide were exposed to secondhand smoke in 2023.
• An expert encouraged clinicians to screen women, children and patients with cardiac issues for exposure.

Exposure to secondhand smoke contributed to more than a million and a half deaths worldwide in 2023, a new report in Lancet Public Health shows.

According to Luisa Sorio Flor, MSc, PhD, an assistant professor at the Institute for Health Metrics and Evaluation, a 2011 “landmark” analysis linked 600,000 deaths globally to exposure to secondhand smoke. However, the analysis focused on a limited number of health outcomes in adults and did not include high-burden conditions such as stroke and COPD.

Data derived from GBD 2023 Second-hand smoke Collaborators. Lancet Public Health. 2026;doi:10.1016/S2468-2667(26)00168-4.

To address these limitations, Flor and colleagues conducted what they describe as the first Global Burden of Disease publication specifically designed to evaluate secondhand smoke exposure as an independent global risk factor. The researchers assessed the prevalence of secondhand smoke exposure, along with associated deaths and disability-adjusted life-years (DALYs), across 204 countries and territories between 1990 and 2023.

To improve the estimates, Flor and colleagues incorporated 91 new data sources on workplace exposure and 87 new sources on household composition. They also used a direct exposure model to classify people as exposed or unexposed to secondhand smoke, rather than estimating exposure intensity based on a cigarette-equivalent measure.

The researchers reported that an estimated 2.71 billion (95% uncertainty intervals [UI], 2.44-3.02) people were exposed to secondhand smoking worldwide in 2023, among whom 1.49 billion (95% UI, 1.35-1.65) were women and 767 million (95% UI, 687-858) were aged 0 to 14 years.

In some countries, Flor and colleagues noted that women had 1.8 times greater exposure to secondhand smoke vs. men.

Age-standardized exposure declined by 22.2% (95% UI, 10.6-32.4) over the study period, “yet population growth kept the absolute number of individuals exposed broadly stable,” the researchers wrote.

In 2023, globally, secondhand smoke exposure was tied to 1.66 million (95% UI, 1.33-2.07) deaths, 44.8 million (95% UI, 35.8-54.3) DALYs, 39.1 million (95% UI, 31.4-48.1) years of life lost and 5.73 million (95% UI, 3.83-7.5) years lived with disability.

Ischemic heart disease was the top contributor to secondhand smoking-attributable DALYs (12 million; 95% UI, 9.31-15.2) while lower respiratory infections were the leader among youth (5.16 million; 95% UI, 3.48-7.12).

The researchers noted that the data were self-reported, resulting in potential underreporting, recall bias and misclassification.

Despite the findings, Flor and colleagues highlighted progress from tobacco-reducing policies in the Americas, as “of the 79 countries attaining the highest level of achievement in smoke-free protections globally, 24 are in the Americas, approximately 70% of the countries in that region.”

“Beyond smoke-free legislation, broader tobacco control measures are needed to reduce secondhand smoke exposure, offset population growth and lessen the resulting public health burden,” they concluded. “Although smoke-free policies directly reduce secondhand smoke exposure and indirectly support smoking cessation by shifting social norms, additional measures such as tobacco taxation, marketing bans, plain packaging, and cessation programs are needed to deter smoking initiation and lower smoking prevalence.”

Manu Jain, MD, MSc, ATSF, a professor of pulmonary and critical care medicine at Northwestern University Feinberg School of Medicine who was not involved in the analysis, told Healio that secondhand smoke exposure “is an important clinical problem that maybe we as clinicians don’t pay enough attention to, and it’s something we need to really focus on as much as we do on getting primary tobacco use history.”

Jain encouraged clinicians to screen for exposure in women and children, as “they seem to be more impacted than men, at least in most of the world,” and especially in patients “with cardiac and lung issues.”

For more information:

Manu Jain, MD, MSc, ATSF, can be reached at primarycare@healio.com.