Second-hand smoke (SHS) is one of the most important and most widespread exposures in the indoor environment. The link between SHS and several health outcomes, such as respiratory infections, ischaemic heart disease, lung cancer and asthma, have long been established. Nevertheless, 93% of the world population is still living in countries not covered by 100% smoke-free public health regulations, and exposure to SHS in the home is still common.
Globally, more than a third of all people are regularly exposed to the harmful effects of smoke. This exposure is responsible for about 600,000 deaths per year, and about 1% of the global burden of disease worldwide. This risk factor is prevalent in practically every region of the world.