Year-Round Observations of NO, NO2, O3, SO2, and Toluene Measured with a DOAS System in the Industrial Area of Puertollano, Spain

Abstract

We report observations of primary and secondary atmospheric pollutants such as nitrogen oxides, sulfur dioxide, toluene, and ozone during the period February 2002 to August 2003 in Puertollano, an industrial area located in central–southern Spain. The measurements were performed using a commercial differential optical absorption spectroscopy instrument. From the hourly data, we have analyzed the mean seasonal levels and the daily evolution and we have examined the occurrence of elevated pollution episodes. The daily cycles of NO, NO2, SO2, and toluene were characterized by an early-morning maximum whereas O3 peaks were monitored around noon. Seasonally, the highest hourly mean concentrations of NO, NO2, SO2, and toluene, 14.2, 27.0, 34.4, and 12.1 μg m−3 respectively, were found in the winter while O3 summer levels reached 119.1 μg m−3. The dataset presented here shows episodic occurrences of elevated concentrations that exceeded the maximum levels established in the European Directives. For instance, hourly values for SO2 were repeatedly measured above 350 μg m−3. During the period of measurements, the O3 thresholds (i.e., hourly value of 240 μg m−3) defined to protect the human health have also been exceeded numerous times. Finally, we investigate daily and seasonal patterns in pollution levels within the context of local meteorology and photochemistry, vehicular traffic, and industrial emissions.