SUSTAINABLE AND HEALTHY CITIES: RELATIONSHIP BETWEEN URBAN GREEN SPACES AND HEALTH INDICATORS IN ADOLESCENTS.

Abstract

Although some research suggests that urban green spaces (UGS) can help reduce obesity by stimulating the practice of physical activity (PA), the evidence is still inconsistent and, in addition, few studies have investigated the association between biodiversity and physical health. In view of this, more and more investigations are devoted to analyzing the relationship between UGS and species diversity with health indicators, especially in adolescent populations. The present thesis aims to analyze the associations between the characteristics of the UGS, namely the offer of spaces, amount of green and species richness, with the Body Mass Index (BMI) and PA in Portuguese adolescents, since these indicators seem to strongly associated with general health. This cross-sectional study was carried out with students between 12 and 18 years old, selected for convenience. Data were collected in public secondary schools, located in municipalities in the Porto Metropolitan Area between February 2014 and May 2019. The PA levels were assessed using accelerometers and information on height, weight, age, gender and residential addres, were obtained through a self-administered questionnaire. The BMI was categorized according to age- and sex-specific cutoffs into normal weight, overweight and obesity. The UGS number, greenness exposure and species richness were measured in buffers of 300, 500, 1000 and 1500 meters around the residence and school of each participant, by Geographic Information System, normalized difference vegetation index and species richness index, respectively. The socioeconomic deprivation of residential and school areas was assessed using the European Deprivation Index for Portuguese small-areas. The main results showed that in the residential environment, the availability of UGS, greenness exposure and species richness were not associated with PA and overweight or obesity incidence rates, and regard to the school environment, the analyzes did not support the idea that UGS, greenness exposure and species richness may be able to promoting PA and metabolic health in adolescents. The results obtained, although inconsistent, add evidence to literature, as they provide an initial perspective on the subject. As the relationships between UGS availability, greenness exposure and species richness with PA and BMI appear to be complex and may implicate other factors, future studies are particularly relevant for urban planning and green space management, and consequently for the biodiversity and health of young urban populations.