Seasonal analysis of air pollution levels in Madrid

Madrid city has a high density of population and suffers from chronic conge stion problems. It means that some pollutants could produce atmospheric eme rgency situations when weather stability periods last longer. Due to the lo w level of industry in the region, mobile sources have an important contrib ution to total emissions. Madrid has a 20-year-old air pollution control ne twork which is composed of 24 permanent stations which control all pollutan ts and atmospheric variables. This paper analyses inmission values from 199 0 to 1997. The analysis covers main pollutant values and their variations w ithin the week and between seasons. The study has a twofold approach: mean- daily values and semi-hourly values. The results allow to draw some conclus ions about inmission values in different areas of the city and how traffic- flow contributes to them. (C) 1999 Elsevier Science B.V. All rights reserve d.