**1. Introduction**

This is a very relevant chapter in the context of "Lung Inflammation" because it details and discusses an important theme in this area: air pollution. The analyses of epidemiological studies, conducted in various urban centres, have provided coherent evidence that elevated levels of air pollution are associated with an increased risk of respiratory disease and mortality. The whole population is affected, but the active and athletic population is of special concern because of the amount of time they spend training and/or competing outdoors, eliciting high ventila‐ tion rates that result in higher pollutants delivery to the lungs.

This chapter addresses the systemic effects that inhaled pollutants have as well as the local pulmonary inflammatory processes and oxidative stress. The consequences that these process‐ es may impose to the health and performance of the active population will also be described. The use of antioxidants to counteract the deleterious oxidative stress of exercise when per‐ formed in a polluted environment is discussed here too.
