A wide analysis published in The Lancet Public Health thus maps a highly uneven geography of passive smoking risk, striking especially women and children.
Secondhand Smoke: A Persistent Global Exposure
In 2023, about 2.71 billion people were exposed to secondhand smoke. Among them were 767 million children aged 0 to 14. Globally, the exposure prevalence reached 33.9%. It was still 43.6% in 1990, a relative decline of 22.2%, according to a large global study published on September 7, 2026 in The Lancet Public Health.
The decline is real. Yet it is not enough to substantially reduce the number of people affected. Among children, prevalence fell from 51.7% to 37.9%. In other words, regulatory progress and the decline in smoking in several parts of the world have reduced the average individual risk, but population growth absorbed a large share of that gain.
The demographic weight becomes even more evident when looking at the three countries with the most exposed people. China accounted for about 664 million in 2023. India had about 444 million that year. Indonesia followed with about 142 million exposed. Together, these three populations account for nearly half of the global total.
This snapshot does not mean that every person breathes the same amount of smoke or faces the same risk. The study distinguishes exposures at work and at home and excludes people who smoke daily to avoid mixing the effects of active smoking, which is far more intense, with secondhand smoke. This methodological separation helps to better isolate the health burden borne by non-smokers.
Africa and the Middle East: exposure rises despite declines in smoking
It is in Africa that the gap between improving rates and rising numbers of exposed individuals appears most starkly. In Sub-Saharan Africa, the absolute number of exposed individuals has risen by 98.5% since 1990, with a 62 to 144.4% uncertainty interval. In North Africa and the Middle East, the increase stands at 72.1%.
“The share of the population exposed is decreasing, but not as fast as the population is growing in these regions,” explains Luisa Sorio Flor, a researcher at the Institute for Health Metrics and Evaluation. Demographic dynamics are therefore a central part of the problem. In some regions, the reduction in prevalence simply isn’t enough to offset the arrival of new generations into environments where smoke remains common, particularly at home.
The situation differs in Latin America and the Caribbean, where prevalence has fallen 38% since 1990. High-income countries have seen a 32% decline over the same period. In Europe, contrasts remain marked. Central Europe, Eastern Europe, and Central Asia still had a prevalence of 37.7%, affecting 146 million people. By contrast, Denmark recorded a 48.8% reduction since 1990, while Norway decreased exposure by 44.3%.
However, Southeast Asia, East Asia, and Oceania remain the large region where age-standardized prevalence stays the highest: 48.4%. The gender gap there is striking. Women showed a prevalence of 59.5%, compared with 37.4% among men. Globally, exposure affected 37.3% of women and 30.6% of men.
This difference does not necessarily mean that women smoke more. In several Asian countries, it is precisely the opposite. When male smoking is widespread and female smoking is low, a large number of non-smoking women can be exposed at home because they live with a smoker, the researchers explain. Secondhand smoke thus becomes a health risk produced by household structure as much as by individual habits.
Secondhand Smoke: the Smoke Weighs on the Heart First, and Children Remain Particularly Exposed
Secondhand smoke is not only linked to lung diseases. In 2023, exposure to secondhand smoke was associated with 1.66 million deaths, with an uncertainty interval between 1.33 and 2.07 million. It also accounted for 44.8 million disability-adjusted life years, ranging from 35.8 to 54.3 million. This indicator sums years of life lost due to premature death and years lived with disease or disability.
Ischemic heart disease is the main contributor to this health loss. It accounts for 12 million disability-adjusted life years, with an interval ranging from 9.31 to 15.2 million. This disease occurs when blood flow and thus oxygenation to the heart muscle become insufficient. Secondhand smoke is also associated, in the analysis, with strokes, chronic obstructive pulmonary disease, asthma, type 2 diabetes, as well as several cancers, notably those of the trachea and the lung.
For children, the health profile is different. Lower respiratory tract infections constitute the leading source of the burden attributable to secondhand smoke, accounting for 5.16 million disability-adjusted life years. Children would account for more than 12% of the global health burden related to secondhand smoke.
The very composition of smoke also poses problems. A non-smoker near a cigarette inhales both the exhaled smoke from the smoker and the smoke coming directly from the burning product. The latter is unfiltered and contains, in roughly equal amounts, higher concentrations of several toxic and carcinogenic substances than the smoke inhaled through the cigarette.
Public smoking bans: coverage remains uneven
Public policies, however, have shown that they can reduce exposure. Bans on smoking in offices, transportation, restaurants, and other public spaces have accompanied a clear decline in many countries. But about 70% of the global population still lacks full protection against smoke in public places.
In 2024, only 79 countries had reached the highest level of protection anticipated in the WHO reference framework. Global coverage by comprehensive legislation rose from 3% of the population in 2007 to 33% in 2024. These rules protected about 2.6 billion people. The movement is therefore massive, but remains far from complete given the billions of individuals still exposed.
The authors remind that smoking bans are only one component of the response. Tobacco taxation, advertising restrictions, plain packaging, and cessation support can work upstream to reduce the number of smokers. Home protection remains a major blind spot, precisely because governments find it difficult to apply the same prohibitions there as in public spaces.
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