Secondhand smoke is associated with approximately 1.7 million deaths globally each year, according to a major study published in The Lancet Public Health. The research, which assessed second-hand smoke as a global risk factor for the first time, estimates that 2.71 billion people were exposed to the smoke in 2023, including 767 million children.
Researchers from the University of Washington estimated exposure levels in 204 countries and combined this data with existing studies on the increased risk of nine diseases, including heart disease, stroke, and lung cancer, due to passive smoking. This methodology allowed them to estimate the number of deaths attributable to secondhand smoke.
Heart disease was identified as the leading cause of death linked to secondhand smoke, accounting for an estimated 537,000 deaths in 2023. Other major causes include chronic obstructive pulmonary disease (COPD) with 354,000 deaths, stroke with 278,000 deaths, lower respiratory infections with 185,000 deaths, and lung, bronchial, and tracheal cancers with 161,000 deaths.
The regions of South East Asia, East Asia, and Oceania reported the highest toll, with approximately 689,000 deaths linked to secondhand smoke. South Asia followed with around 428,000 deaths. The study highlights that persistent high smoking rates in many Asian countries, including China, India, and Indonesia, contribute to a high proportion of global exposure.
While the proportion of people exposed to secondhand smoke has fallen by about 22% since 1990, population growth has kept the total number of deaths roughly consistent. The study also noted that the estimated figures may not capture the full impact, as exposure in places like cars and hospitality venues, as well as the duration of exposure, were not included.
In contrast to global trends, the United Kingdom has experienced significant progress. In 2023, secondhand smoke was estimated to be responsible for 6,100 deaths in the UK, a substantial decrease from approximately 14,900 deaths in 1990. This reduction is attributed to factors such as a decline in adult smoking rates from around 30% in 1990 to about 10% today, alongside measures like standardized cigarette packaging and advertising bans.
Despite these improvements, the health burden remains considerable. In 1990, secondhand smoke was linked to around 385,000 years of healthy life lost in Britain due to illness, disability, or premature death. By 2023, this figure was still around 171,600 years.
Experts emphasize that even brief exposure to secondhand smoke can be harmful, and exposure during pregnancy is linked to adverse outcomes such as premature birth, low birthweight, and sudden infant death syndrome. The study's authors advocate for stronger global measures, including increased tobacco taxes, advertising bans, plain packaging, and enhanced access to smoking cessation programs.