Fine particle concentrations in buses and taxis in Florence, Italy M. Cristina Fondelli a, * , Elisabetta Chellini a , Tarja Yli-Tuomi b , Isabella Cenni c , Antonio Gasparrini a , Silvia Nava d , Isabel Garcia-Orellana d, e , Andrea Lupi f , Daniele Grechi f , Sandra Mallone a , Matti Jantunen b a Environmental and Occupational Epidemiology Unit, Institute for Study and Prevention of Cancer (ISPO), Street of S. Salvi, 12, 50136 Florence, Italy b National Public Health Institute (KTL), Division of Environmental Heath, Kuopio, Finland c Occupational Toxicology and Industrial Hygiene Unit, Public Health Laboratory, Prevention Department, Local Health Unit 10 (ASL 10), Florence, Italy d Istituto Nazionale di Fisica Nucleare (National Institute of Nuclear Physics, INFN), Division of Florence, Italy e National Centre for Accelerators, Sevilla, Spain f Air Quality Protection Unit, Provincial Department of Florence, Regional Environment Protection Agency of Tuscany (ARPAT), Italy article info Article history: Received 20 March 2008 Received in revised form 25 July 2008 Accepted 28 July 2008 Keywords: PM 2.5 Traffic Commuting exposure Elemental composition Black Smoke Index abstract On October 2004, a sampling survey was carried out in Florence to estimate urban fine particle exposure concentrations inside commuting vehicles during workdays character- ized by heavy traffic. Portable samplers were positioned inside four regularly scheduled diesel-powered buses and four taxis during eight weekdays. Each sampler consisted of a 2.5 mm size pre-separator cyclone, a direct-reading data logging photometer (pDR-1200), and a 4 L min 1 filter sampler for the determination of PM 2.5 mass concentration. Based on reflectance analysis measurements, a PM 2.5 Black Smoke Index was determined for each filter, and the elemental composition of the PM 2.5 was analyzed by Particle Induced X-ray Emission (PIXE). PM 2.5 mass concentrations inside the vehicles correlated well with the urban ambient air PM 2.5 concentrations measured at the fixed-site monitoring stations. The PM 2.5 excess above the urban ambient level was on average 32 mgm 3 (range: 22–52 mgm 3 ) and 20 mgm 3 (range: 11–29 mgm 3 ) in buses and taxis, respectively. The PM 2.5 -bound sulfur concentration was also higher in the buses than in the taxis. Based on daily Time-Microenvironment-Activity-Diary (TMAD) data, the Florentines spend on average 9.7% of their day in traffic, and the corresponding average exposure is approxi- mately 12% of their daily PM 2.5 personal exposure. The obtained data could be used to plan interventions to minimize the PM 2.5 citizen exposures in commuting. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction Epidemiological studies (US-EPA, 2004; WHO, 2005; Pope et al., 2002, 2004) have associated adverse and severe health outcomes with exposure to ambient air Particulate Matter less than 2.5 mm in aerodynamic diameter (PM 2.5 ), especially among susceptible sub-populations, e.g., infants, the elderly, and subjects with cardiopulmonary diseases. In urban areas, a large fraction of the PM 2.5 pollution originates from local mobile sources: mainly diesel- powered vehicles and twin stroke engine powered motor- cycles (Kinney et al., 2000), and stationary combustion processes (heating and industrial). PM 2.5 from local and micro-environmental sources is superimposed on a varying regional background PM 2.5 , which consists of primary particles, originating from combustion emissions and soil dust, and secondary aerosols (ammonium sulfate and nitrate, and organics). Florence (102.3 km 2 , and 367 000 inhabitants) is located in Central Italy. It is characterized by cold winters and hot * Corresponding author. Tel.: þ39 055 6268346; fax: þ39 055 679954. E-mail address: mc.fondelli@cspo.it (M.C. Fondelli). Contents lists available at ScienceDirect Atmospheric Environment journal homepage: www.elsevier.com/locate/atmosenv 1352-2310/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.atmosenv.2008.07.054 Atmospheric Environment 42 (2008) 8185–8193