How much does the environment affect human health? Is air pollution shortening our lives and those of our children? These questions are fundamental to environmental policies. Air pollution is a major environmental health threat in OECD countries, contributing to a number of illnesses, such as asthma, cancer and premature deaths. Despite national and international interventions and decreases in major emissions, the health impacts of air pollution are not likely to decrease in the years ahead, unless appropriate action is taken. This report presents estimates of the costs and benefits of environmental policies aiming at reducing air pollution and provides policy recommendations in order to better address environmental health issues.