Seasonal analysis of air pollution levels in Madrid.

Madrid city has a high density of population and suffers from chronic congestion problems. It means that some pollutants could produce atmospheric emergency situations when weather stability periods last longer. Due to the low level of industry in the region, mobile sources have an important contribution to total emissions. Madrid has a 20-year-old air pollution control network which is composed of 24 permanent stations which control all pollutants and atmospheric variables. This paper analyses inmission values from 1990 to 1997. The analysis covers main pollutant values and their variations within the week and between seasons. The study has a twofold approach: mean-daily values and semi-hourly values. The results allow to draw some conclusions about inmission values in different areas of the city and how traffic-flow contributes to them.