DMAH ozone measurement net

The complexity of the study of tropospheric ozone lies in the fact that it is a secondary pollutant. It is not emitted by a source, instead its concentration in the air depends on other compounds (especially the nitrogen oxides emitted by motor vehicles and the volatile organic compounds emitted by the industry and the vegetation) and meteorological factors (especially solar radiation and temperature). The European legislation compells to make measurements of the tropospheric ozone due to its effects on people (fatigue, irritation of the mucous membranes, aggravation of asthma ...) and on environment (decrease of the production of cereals, synergy with plagues ...). The measuring net in Catalonia belongs to the Department of Environment and Housing (DMAH). It has a pyramidal structure and it allows a surveillance to notify in case of exceeding a certain threshold. From the registered data of last years it is shown that the number of incidences is related to meteorology. They are more frequent during afternoon and the behaviour of this pollutant is different according to the proximity of the point of measurement to the sources of its precursors.