Influence of urban forest on traffic air pollution and children respiratory health

This study aimed to assess the air quality, the prevalence of child respiratory morbidity, and the association between them, in urban areas where concentrations of pollutants are expected to be below national limits. The monitoring of PM_10, NO₂ and O₃ was performed in five schools, during 9 months. Information about respiratory diseases and associated symptoms were collected from each student using a questionnaire based on the International Study of Asthma and Allergies in Childhood. The PM₁₀ and NO₂ concentrations were higher at points closer to roads and avenues with intense vehicle flow and lower at the point closer to a park, with dense vegetation. All sampling points exceeded the annual limit established by WHO for PM₁₀. Some maximum PM₁₀ concentrations recorded close to the road was six times higher than the international limit. In total, 340 answered questionnaires were collected (68% response rate). Respiratory symptoms such as wheezing, sneezing, running nose, tearing, and itchy eyes had positive and strong correlation to the primary pollutants (0.70 to 0.87), but the frequency of some symptoms was lower close to the urban forest. Therefore, our results confirm the importance of creating and maintaining green areas in urban space, considering all ecosystem services provided by them, especially the improvement of air quality. In addition, a continuous program to monitor and control atmospheric pollution is required in mid-sized counties located nearby important roads, with growing fleets of vehicles.