Second-hand smoke: 2.7 billion exposed, 767 million of them children, study finds

A third of the world’s population is exposed each year to second-hand smoke — also known as passive smoking — which continues to be a major source of illness and mortality among non-smokers. An estimated 2.71 billion people around the world were exposed to second-hand smoke— a combination of two types of smoke inhaled by non-smokers — in 2023, contributing to 1.66 million deaths. This includes 767 million children under 15, who are especially vulnerable, along with 1.49 billion women. These new findings come from the Global Burden of Disease (GBD) 2023 study, published in The Lancet Public Health, which estimated second-hand smoke exposure and health impacts across 204 countries and territories between 1990 and 2023.

Need for stronger regulation

Despite the scale of exposure, the study found that approximately 70% of the world’s population is not protected by comprehensive smoke-free laws. As of 2024, only 79 countries, approximately 70% of them in the Americas, have achieved the highest protection standards of the World Health Organization framework — with all public places completely smoke-free or at least 90% of the population covered by legislation. The proportion of the global population covered by comprehensive smoke-free legislation has increased from 3% in 2007 to 33% in 2024, now covering 2.6 billion people. However, the authors noted that while smoke-free policies directly reduce smoke exposure, there is a need for extra measures such as tobacco taxation, marketing bans, plain packaging and cessation programmes.

Regional patterns

The researchers found that the number of people impacted by second-hand smoke exposure remained broadly the same globally, but rose sharply in sub-Saharan Africa, North Africa and the Middle East, which they attributed to population growth. The exposure prevalence in the Central Europe, Eastern Europe and Central Asia region was 37.7% — higher than the global average of 33.9% — affecting 146 million people. Most of the countries in Western Europe were included in the “high-income super region,” which showed some of the most significant progress in reducing passive smoking. Denmark and Norway achieved some of the world's largest reductions since 1990, at -48,8% and -44,3%, respectively.

Broad health impacts

Beyond how many people are exposed, the report found that second-hand smoke accounted for the loss of 44.8 million years of healthy life and continues to be a major contributor to disability and premature death. While a smoker inhales "mainstream smoke" through the cigarette's filter, non-smokers primarily breathe in sidestream smoke. This is unfiltered and contains higher per-unit concentrations of toxic and carcinogenic compounds than the smoke inhaled by the smoker. The researchers estimated that second-hand smoke remains a substantial driver of global health loss, particularly through cardiovascular and paediatric respiratory diseases. Exposure to tobacco smoke was associated with several health conditions, including stroke, lower respiratory infections, chronic obstructive pulmonary disease, asthma, type 2 diabetes and cancers of the trachea, lung and breast.