Monitoring of tropospheric ozone in the ambient air with passive samplers Daniellys Alejo a, ⁎, Mayra C. Morales b , Vladimir Nuñez c , László Bencs d, e , René Van Grieken d , Piet Van Espen d a Department of Chemistry, Universidad Central de Las Villas, Carretera a Camajuaní Km 5.5, Santa Clara, Cuba b Department of Chemistry Engineering, Universidad Central de Las Villas, Carretera a Camajuaní Km 5.5, Santa Clara, Cuba c Provincial Meteorological Center of Villa Clara, Marta Abreu No. 57 (altos) e/ J.B. Zayas y Villuendas, Santa Clara, Cuba d Department of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium e Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest, Hungary abstract article info Article history: Received 8 June 2011 Accepted 13 June 2011 Available online 7 July 2011 Keywords: Tropospheric ozone Radiello passive samplers Air quality monitoring Atmospheric gaseous pollutants Seasonal trends Two sampling campaigns in suburban places in the north zone of Santa Clara city, Cuba, have been carried out on a weekly base with the use of Radiello passive diffusion tubes in order to monitor the tropospheric ozone (O 3 ) levels in 2010. The first campaign was scheduled from February to April (cold season) and the second one in August and October (warm season), both of them at two sampling sites, i.e., Farm and School of Art Instructors. After aqueous extraction, the samples were analyzed by UV–VIS spectrophotometry. A seasonal trend was observed with the maximum O 3 concentrations in the cold season and the minimum levels in the warm season. Samples collected during the cold season showed the highest O 3 levels. Higher levels were reached at the Farm site with average values of about 58 ± 12 μg/m 3 , which exceeded the limit of the Cuban Standard 99:1999. In the warm season, the O 3 concentrations were similar for both sites, but lower than those observed in the cold season. The overall, seasonal average value was found to be 24 μg/m 3 . Despite the higher weekly average temperatures in August, the O 3 concentrations during this month showed the lowest values of the whole sampling period, which finding is in agreement with that reported by the Meteorological Institute of Cuba. Mathematical models, based on the Cochrane-Orcutt algorithm, were fitted to the acquired data set to explain the change in the tropospheric ozone concentrations under various meteorological conditions during the two campaigns. The correlation coefficients for both the cold and the warm seasons demonstrated a strong correlation, i.e., 0.779 and 0.951, respectively. The high correlation of wind speed in the model from the first sampling campaign explains the sharp decrease in O 3 concentrations at the SAI sampling site from the sixth week of sampling. © 2011 Elsevier B.V. All rights reserved. 1. Introduction The presence of ozone (O 3 ) in the troposphere is understood to arise from two basic processes: tropospheric / stratospheric exchange that causes the transport of stratospheric air, rich in ozone, into the troposphere; and production of ozone from photochemical reactions occurring within the troposphere [1–4]. Ozone is produced in the troposphere as a consequence of interaction of meteorological conditions, sunlight, nitrogen oxides (NOx), O 2 and volatile organic compounds (VOCs) [1,4–6]. The study of this pollutant is interesting from environmental point of view due to its harmful impact on the biosphere, human health, animal population, agriculture productivity and forestry [1,3,7,8]. Therefore, the monitoring of O 3 levels in the ambient air is needed and justified. Initially, this phenomenon was attributed to highly industrialized countries, but nowadays, it extends to other countries of smaller developments like Cuba. Ozone, under the influence of some meteorological phenomena, such as cold fronts, hurricanes and high pressures systems, can move over long distances. Sharing the same general pattern with several other air pollutants, at most sites, O 3 levels fluctuate seasonally. It is generally higher in winter than summer [2,9]. Meteorology plays an important role in ozone formation and transport. As a result, substantial variations in meteorological conditions can exert such a large impact on ozone concentrations [1]. Anticyclonic pressure systems and low or calm wind conditions promote the accumulation of ozone. Different contributions to the ozone levels may come from the background ozone that originates from stratospheric injection and production far away from local sources, meaning that it involves photooxidation of CH 4 and CO, and regional photochemical production and depletion of O 3 by deposition and loss reactions [10]. Microchemical Journal 99 (2011) 383–387 ⁎ Corresponding author. Tel.: + 53 42 281164, + 53 42 211825, + 53 42 211826x106. E-mail address: daniellysas@uclv.edu.cu (D. Alejo). 0026-265X/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.microc.2011.06.010 Contents lists available at ScienceDirect Microchemical Journal journal homepage: www.elsevier.com/locate/microc