4. Studies on health effects of transport-related air pollution

Evidence from epidemiological and toxicological studies on the effects of transport-related air pollution on health has increased substantially, although it is only a fraction of the total evidence on the effects of urban air pollution on health. A review of this evidence indicates that transport-related air pollution affects a number of health outcomes, including mortality, non-allergic respiratory morbidity, allergic illness and symptoms (such as asthma), cardiovascular morbidity, cancer, pregnancy, birth outcomes and male fertility. Transport-related air pollution increases the risk of death, particularly from cardiopulmonary causes, and of non-allergic respiratory symptoms and disease. Experimental research indicates that the effects are linked to changes in the formation of reactive oxygen species (ROS), changes in antioxidant defence, and increased non-allergic infl ammation, thus articulating some parameters of susceptibility. While laboratory studies indicate that transport-related air pollution may increase the risk of developing an allergy and can exacerbate symptoms, particularly in susceptible subgroups, the evidence from population studies that supports this conclusion is inconsistent. Though only a few studies have been conducted, a signifi cant increase in the risk of heart attack (myocardial infarction) following exposure to transport-related air pollution has bee