|Citation: Boletin de la Asociacion de Geografos Espanoles, 2007,44, 301- *
Last years there is a growing awareness about the fact that pollutant emissions produced by human activities, when spreading across space, do not fairly affect to different social categories. It has been often observed that most disadvantaged groups suffer more severely these negative externalities, so generating environmental injustice. This paper tackles the diagnosis of the extent the negative externalities, derived from sulphur dioxide atmospheric pollution, unequally affect to the zones populated by the distinct income groups in Madrid, in order to check the environmental equity / inequity they could cause in two years, 1995 and 2005. To this end two data sources are used: income per capita by small spatial units and the pollution registered in the ground surveillance observatories. The later data, associated to point locations, have served as input to produce, by spatial interpolation, raster layers estimating the atmospheric concentration of the pollutant, and then a cross-tabulation between the income and the sulphur dioxide raster layers has been obtained to determine the relative level of affection suffered by each income group. Analyzing the facts in two years allows to assess the output, in terms of environmental equity, of the policy promoting heaters modernization and the derived reduction in sulphur dioxide emissions. The method illustrates how GIS analysis can be effectively applied to diagnose geographical situations, and so to analyze public policies and to make spatial decisions taking into account the nowadays well established principle of environmental justice.
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