Social status and air quality in Barcelona: A socio-ecological approach

Abstract

• There is a relationship between higher building density and higher air pollution. • There is an inverse relationship between the isolated street trees and less pollution. • The areas with higher income level are related with the worse the air quality • The GWR models show a more complete view that OLS models for the air quality studies. During the last two decades, many studies have described the effects of air pollution in urban areas. This paper analyses the spatial patterns of the main air pollutants in the city of Barcelona, i.e. nitrogen dioxide (NO 2 ), fine particulates of less than 2.5μm (PM 2.5 ) and coarse particulates of 10μm (PM10), and explores the factors associated with air quality in relation to the social and environmental characteristics of each area of the city using 1068 census tracts. The city exhibits a situation of high annual averages of pollutants regarding the World Health Organization (WHO) guidelines and the European Union regulations, with most of the census tracts with amounts of NO 2 >20 µg/m 3 , PM 2.5 >10 µg/m 3 and PM 10 >20 µg/m 3 . To analyse the spatial pattern, we use exploratory spatial data analysis (ESDA) and estimation of spatial econometric models. We test global and local spatial autocorrelation, and we identify spatial clusters of pollutants with the Local Moran cluster map. We use different geographically weighted regression (GWR) approaches to provide local insight and to consider the spatial heterogeneity of the relationships analysed, including standard GWR, multiscale and mixed techniques. Our results for Barcelona reveal a clear relationship, but with opposite signs depending on the census tract, between the pollutants commonly analysed and population density (from -2.17 to 3.69, median 1.3), income (from -7.20 to 20.55, median 6.45) and population aged 0-4 (from -1.96 to 12.38, median 0.74).