Using an objective model to estimate overall ozone levels at different urban locations

Abstract

Ground-level tropospheric ozone is one of the air pollutants of most concern. Ozone levels become particularly high in regions close to high ozone precursor emissions and during summer, when high insolation and high temperatures are common. Ozone levels continue to exceed both target values and the long-term objectives established in EU legislation to protect human health and prevent damage to ecosystems, agricultural crops and materials. Researchers or decision-makers frequently need information about atmospheric pollution patterns in urbanized areas. The preparation of this type of information is a complex task, due to the influence of several factors and their variability over time. In this work, some results of urban ozone distribution patterns in the city of Badajoz, which is the largest (140,000 inhabitants) and most industrialized city in Extremadura region (southwest Spain) are shown. Twelve sampling campaigns, one per month, were carried out to measure ambient air ozone concentrations, during periods that were selected according to favourable conditions to ozone production, using an automatic portable analyzer. Later, to evaluate the overall ozone level at each sampling location during the time interval considered, the measured ozone data were analysed using a new methodology based on the formulation of the Rasch model. As a result, a classification of all locations according to the ozone level, which was the value of the Rasch measure, was obtained. Moreover, information about unexpected behaviours of ozone patterns was generated. Finally, overall ozone level at locations where no measurements were available was estimated which can be used to generate hazard assessment maps.