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Author(s): Pires, JCM
Martins, FG
Title: Surface ozone concentrations in London: Temporal and spatial patterns
Issue Date: 2012
Abstract: Surface ozone (O3) is one of the most important pollutants in the atmosphere, causing several damages on human health, climate, vegetation and materials. It is a secondary pollutant, produced by photochemical reactions that occur in atmospheres with nitrogen oxides and volatile organic compounds as main precursors. O3 is also transported vertically from stratosphere or horizontally by the wind from regions where it was produced. Thus, this pollutant presents a complex behaviour and it requires several studies aiming to improve the scientific knowledge related to this topic and at same time to help the justification of some O3 episodes. This study aims to apply statistical methods to evaluate the temporal and spatial patterns in a large european urban area -London. The specific objectives are: (i) to analyse the tendency of the annual average concentrations in several monitoring sites; (ii) to evaluate the exceedances to the legislated limits by the European Union for human health protection; (iii) to assess the ozone weekend effect; (iv) to identify city areas with similar O3 behaviour using principal component analysis; (v) to evaluate daily and annual profiles of O3 concentrations; and (vi) to correlate O3 concentrations with meteorological variables. The statistical methodologies were applied to O3 concentrations measured at 38 monitoring sites of the London Air Quality Monitoring Network (selected according their monitoring efficiency) from January 2007 to December 2009. However, the annual tendency was only evaluated at monitoring sites, which present O3 measurements for at least 10 years. For almost all the selected monitoring sites, the annual average O3 concentrations are increasing at a rate between 0.40 to 0.85 g m-3 yr-1. O3 concentrations presented few exceedances to legislated limits for human health protection. The principal component analysis grouped the 38 monitoring sites in 6 groups with similar O3 behaviour. It showed that there are now city areas with a specific O3 behaviour covered by more than one monitoring site, suggesting then an ineffective management of the air quality monitoring system. The redundant equipment should be transferred to other monitoring sites allowing enlargement of the monitored area. The O3 profiles showed the main differences of O3 behaviours at several places in London. The highest concentrations (diurnal and nocturnal) were measured in May. The analysis of the linear relationship with meteorological variables showed that O3 concentrations is positively correlated with barometric pressure, temperature and wind speed and negatively correlated with relative humidity.
Subject: Ciências do ambiente, Engenharia do ambiente
Environmental science, Environmental engineering
Scientific areas: Ciências da engenharia e tecnologias::Engenharia do ambiente
Engineering and technology::Environmental engineering
Source: Ozone and Ozone Depletion: Sources, Environmental Impact and Health
Related Information: info:eu-repo/grantAgreement/FCT - Fundação para a Ciência e Tecnologia/Programa de Financiamento Plurianual de Unidades de I&D/FCOMP-01-0124-FEDER-022677/PROJECTO ESTRATÉGICO - UI 511 - 2011-2012/PEst-C/EQB/UI0511/2011
Document Type: Capítulo ou Parte de Livro
Rights: restrictedAccess
Appears in Collections:FEUP - Capítulo ou Parte de Livro

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