Assessment of an air pollution event in the southwestern Iberian Peninsula

On 12 and 13 August 2006, an exceptional air pollution event occurred in the southwest of the Iberian Peninsula (western Andalusia). High concentrations of surface ozone, CO and PM10 were registered at several air quality stations, in some cases reaching record values. During the late afternoon and evening of these two dates, the information and alert thresholds of surface ozone at coastal stations were exceeded, with peaks of 270 mu g m(-3). Concentrations of CO and PM10 reached 1800 mu g m(-3) and 240 mu g m(-3). Surface meteorological observations, back trajectories computed with the HYSPLIT model and wind and specific humidity fields from the meso-meteorological WRF-ARW model have all been used to gain an understanding of the origin of this event. The results indicate that this event was caused by the long-range transport of air masses from the wildfires that had occurred in the northwest of the Iberian Peninsula (Galicia and northern Portugal) during the first two weeks of August 2006. Air masses loaded with pollutants were transported approximately 1000 km from north to south, over Portugal and the Atlantic Ocean, to reach the southwestern Iberian Peninsula, with the consequent negative high impact on the air quality of this region. (C) 2012 Elsevier Ltd. All rights reserved.