Air pollution and health: indoor air pollution in the developing world is the real key to reducing the burden of ill health.

We welcome the editorial by Thurston highlighting the effects of air pollution on health.1 Air pollution has been shown to have an important effect on the mortality of those with pre-existing respiratory and cardiovascular conditions.2 Outdoor sources of air pollution are important contributors to indoor air pollution concentrations, particularly in developed countries. However, global human exposure to particulate matter (PM)—in terms of the number of people, exposure intensity and time spent exposed in …