The WHO estimates that, of all diseases, lower respiratory tract infections are the second most attributable to environmental factors (WHO 2006). Such infections are frequently caused by air pollution. The 2008 EPI seeks to capture the health risks posed by air pollution with three indicators: Indoor Air Pollution, Urban Particulates, and Local Ozone. These indicators represent environmental risks faced by countries at both ends of the economic spectrum. Measuring both indoor and outdoor air pollution is important because countries are unequally affected by each type of risk. Indoor air pollution tends to pose greater health risks in developing countries, while outdoor air pollution tends to pose risks in more industrialized nations. Thus, the air pollution indicators selected for use in the 2008 EPI identify environmental risks of relevance to all countries.
