SUMMARYEcological studies in epidemiology present some limitations on assessing the exposure of environmental factors. The main objective of this study was to describe a statistical methodology that could help on more accurately assessing the relationship between air pollution and health responses at very small spatial scale.In particular, we modelled the spatial distribution of nitrogen dioxide (NO 2 ) and of particles with a diameter of less than 10 mm in two study areas, the metropolitan areas of Barcelona (MABa) and Bilbao (MABi). The areas chosen for this project can be distinguished for having similar population density and urban surface, as well as high road traffic intensity. The geographical variability of the pollutants could differ greatly due to very different orographic and climatic conditions. Three contributions of this study could be mentioned. First of all, the spatial distribution of the values of each air pollutant was spread over the entire study region on a small area basis, that is census track in our case. Secondly, a stochastic interpolation method, kriging, was used. Thirdly, instead of estimating the average value of the pollutant at the centroid of the area for the entire study period, the value was estimated for each and every day of the corresponding period.As regards the main results, in both areas it can be observed that those census tracks with a greater concentration of pollutants are those that were estimated more accurately. This suggests the existence of a persistent emission source in those tracks, very probably those roads with greater road traffic intensity.

No abstract

No abstract