In 2016, an estimated one-fifth of males and one-third of females globally were exposed to secondhand smoke. Although secondhand smoke usually come from cigarettes, smoking other tobacco products (such as waterpipe) is common in some populations and can substantially contribute to secondhand smoke exposure.
Exposure to secondhand smoke is associated with numerous adverse health effects, even among children and unborn babies, and causes substantial mortality and morbidity globally. In 2016 alone, for example, it caused an estimated 884,000 deaths. The years of life lost due to ill-health, disability, or early death because of secondhand smoke was 6.4 million years for lower respiratory infections, 2.5 million for chronic obstructive pulmonary disease, and more than 200,000 for middle ear infection.
Exposure to secondhand smoke is common in many countries, notably in Asia. In Indonesia and Pakistan, for example, more than 80% of people are exposed to secondhand smoke in restaurants.
Variations in smoke-free laws and enforcement of these laws greatly affects levels of exposure. Due to these variations, prevalence of exposure to secondhand smoke in bars and restaurants is relatively low in several European Union member states (<10%) but is far higher in some others (e.g., nearly 80% in Greece in 2017). After implementation of comprehensive laws in Turkey in 2009, exposure prevalence in workplaces and restaurants dropped substantially— from 37% and 56% respectively in 2008 to 16% and 13% in 2012.
Prevalence of secondhand smoke exposure in many countries with a low Human Development Index (e.g., in sub-Saharan Africa) is low simply due to relatively low smoking prevalence. However, even those countries must implement or enforce existing comprehensive smoke-free laws to protect their populations. With current trends, many of them are likely to see a substantial increase in smoking, and consequently, secondhand smoke prevalence.
Within countries, some groups demonstrate higher exposure levels and related burden, such as those of lower socioeconomic groups and non-smoking women. For example, secondhand smoke causes more deaths in women than in men globally (573,000 vs. 311,000 in 2016) and more lung cancer deaths among women than men in China (40,000 vs. 12,000 in 2013). Returning to the example of Turkey, the decline in prevalence of exposure at home (from 56% to 38%) was smaller than the decline in public places, reinforcing the importance of focusing on exposure inside the home. In many population, homes are the main place of exposure to secondhand smoke for women and children.