title: Thirteen years of air pollution hourly monitoring in a large city: potential sources, trends, cycles and effects of car-free days.
abstract: Thirteen air pollutant concentrations were measured hourly for 13 years (2000-2013) at an urban background site of a large city in the eastern Po Valley (Italy) and results were chemometrically analysed. The pollutant list includes CO, NO, NO2, NOx, O3, SO2, benzene, toluene, ethylbenzene, o-, m- and p-xylenes and PM10, all known or suspected of having adverse effects on human health. The hourly data were statistically processed to detect the long-term trends in relation to the changes in the emission scenarios occurred in the last decade. The most probable emission sources and atmospheric photochemical processes were investigated by analyzing the seasonal, weekly, diurnal cycles of pollutants and the lagged correlations amongst pollutants. The role of micro-meteorological factors upon the air quality was assessed by analyzing the relationships with key weather parameters, while the location of the potential sources was studied by matching atmospheric circulation and pollution data through bivariate polar plots and conditional probability functions. In addition, a new statistical procedure is presented and tested to analyze the periods when common mitigation measures were adopted in the city (e.g., the total stop of traffic and car-free days) and to evaluate their real effect upon the air quality. By providing direct information on the levels and trends of key pollutants, this study finally enables some general considerations about air pollution in an important hotspot of Southern Europe, the eastern Po Valley, where the levels of some key pollutants are still far from meeting the EC limit and target values. It may help policy-makers to take successful mitigation measures.
authors.affiliation: Division of Environmental Health and Risk Management, School of Geography, Earth & Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom; Dipartimento di Scienze Ambientali, Informatica e Statistica, Università Ca' Foscari Venezia, Dorsoduro 2137, 30123 Venice, Italy. Electronic address: m.masiol@bham.ac.uk.
authors.forename: Mauro
authors.initials: M
authors.lastname: Masiol
authors.affiliation: Dipartimento di Scienze Ambientali, Informatica e Statistica, Università Ca' Foscari Venezia, Dorsoduro 2137, 30123 Venice, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Agostinelli
authors.affiliation: Dipartimento Regionale Laboratori-Sede Operativa di Padova, Agenzia Regionale per la Prevenzione e Protezione Ambientale del Veneto, Via Ospedale Civile 22, 35121 Padova, Italy.
authors.forename: Gianni
authors.initials: G
authors.lastname: Formenton
authors.affiliation: Dipartimento Provinciale di Venezia, Agenzia Regionale per la Prevenzione e Protezione Ambientale del Veneto, Via Lissa 6, 30174 Mestre, Italy.
authors.forename: Enzo
authors.initials: E
authors.lastname: Tarabotti
authors.affiliation: Dipartimento di Scienze Ambientali, Informatica e Statistica, Università Ca' Foscari Venezia, Dorsoduro 2137, 30123 Venice, Italy.
authors.forename: Bruno
authors.initials: B
authors.lastname: Pavoni
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000706:statistics & numerical data*; D001336:Automobiles / Q000706:statistics & numerical data; D002947:Cities; D004784:Environmental Monitoring; D007558:Italy
chemical_list: D000393:Air Pollutants
keywords: Air quality; BTEX; Nitrogen oxides; Ozone; PM(10); Urban pollution