Green spaces, land cover, street trees and cardiovascular health in a megacity

Abstract

GREEN, AIR, LMIC: PECHAKUCHA COMES TO ISEE! Johan Friso Foyer, Floor 1, August 27, 2019, 10:30 AM - 12:00 PM Background: Proximity to green spaces has been shown to be beneficial to several cardiovascular outcomes in urban spaces. Few studies have analyzed the relation of green spaces and land cover uses in the megacities of the developing world, where disordered urbanization and air pollution impose several health hazards. This study used a subgroup of the dataset of The Brazilian Longitudinal Study of Adult Health ELSA-BRASIL (n= 3418) to correlate the medical diagnosis of hypertension to green spaces in the megacity of Sao Paulo. Methods: For each participant, we assessed demographic data and cardiovascular risk factors (smoking habits, body mass index, diabetes, dyslipidemia, excessive drinking, salt consumption and level of physical activity). In the ELSA-BRASIL, hypertension was defined as a systolic BP ≥ 140 mmHg or diastolic BP ≥ 90 mmHg or reported use of medication to treat high blood pressure. Land cover classification was performed using the Random Forest Algorithm (program QGIS2.18.11; Plugin Dtezaka) using an orthophoto with a spatial resolution of 2 m on the pixel side. Using the program QGIS2.18.11, three different indicators of exposure to green spaces were used: land cover, street tree numbers and number of parks within 1 km. Results: The number of street trees in the regional governments (OR = 0.937; p = 0.038; CI (95%): 0.881 to 0.996) and number of parks within 1 km (OR = 0.876; p = 0.047; CI (95%): 0.769 to 0.998) were inversely associated with the diagnosis of hypertension. Sixty-three percent of the population had no parks within 1 km of their residence.Street tress is able to decrease the hypertension diagnosis while others land covers such as grass, green spaces, treetops and roofs are not. Conclusions: Street trees improve cardiovascular health. Our data encourage large-scale tree planting in megacities to mitigate the effects of disordered urbanization.