title: Is particulate air pollution at the front door a good proxy of residential exposure?
abstract: The most advanced epidemiological studies on health effects of air pollution assign exposure to individuals based on residential outdoor concentrations of air pollutants measured or estimated at the front-door. In order to assess to what extent this approach could cause misclassification, indoor measurements were carried out in unoccupied rooms at the front and back of a building which fronted onto a major urban road. Simultaneous measurements were also carried out at adjacent outdoor locations to the front and rear of the building. Two 15-day monitoring campaigns were conducted in the period June-December 2013 in a building located in the urban area of Bologna, Italy. Particulate matter metrics including PM2.5 mass and chemical composition, particle number concentration and size distribution were measured. Both outdoor and indoor concentrations at the front of the building substantially exceeded those at the rear. The highest front/back ratio was found for ultrafine particles with outdoor concentration at the front door 3.4 times higher than at the rear. A weak influence on front/back ratios was found for wind direction. Particle size distribution showed a substantial loss of particles within the sub-50 nm size range between the front and rear of the building and a further loss of this size range in the indoor data. The chemical speciation data showed relevant reductions for most constituents between the front and the rear, especially for traffic related elements such as Elemental Carbon, Iron, Manganese and Tin. The main conclusion of the study is that gradients in concentrations between the front and rear, both outside and inside the building, are relevant and comparable to those measured between buildings located in high and low traffic areas. These findings show high potential for misclassification in the epidemiological studies that assign exposure based on particle concentrations estimated or measured at subjects' home addresses.
authors.affiliation: Regional Centre for Environment and Health, Arpae Emilia-Romagna, Via Begarelli, 13, 41121, Modena, Italy. Electronic address: szauli@arpa.emr.it.
authors.forename: Stefano
authors.initials: S
authors.lastname: Zauli Sajani
authors.affiliation: Regional Centre for Urban Areas, Arpae Emilia-Romagna, Via Rocchi, 19, 40138, Bologna, Italy.
authors.forename: Arianna
authors.initials: A
authors.lastname: Trentini
authors.affiliation: Department of Science and HighTechnology, Università degli Studi dell'Insubria, Via Valleggio 11, 22100, Como, Italy.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Rovelli
authors.affiliation: Regional Centre for Urban Areas, Arpae Emilia-Romagna, Via Rocchi, 19, 40138, Bologna, Italy.
authors.forename: Isabella
authors.initials: I
authors.lastname: Ricciardelli
authors.affiliation: Regional Centre for Environment and Health, Arpae Emilia-Romagna, Via Begarelli, 13, 41121, Modena, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Marchesi
authors.affiliation: Regional Centre for Urban Areas, Arpae Emilia-Romagna, Via Rocchi, 19, 40138, Bologna, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Maccone
authors.affiliation: Regional Centre for Urban Areas, Arpae Emilia-Romagna, Via Rocchi, 19, 40138, Bologna, Italy.
authors.forename: Dimitri
authors.initials: D
authors.lastname: Bacco
authors.affiliation: Regional Centre for Urban Areas, Arpae Emilia-Romagna, Via Rocchi, 19, 40138, Bologna, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Ferrari
authors.affiliation: Regional Centre for Urban Areas, Arpae Emilia-Romagna, Via Rocchi, 19, 40138, Bologna, Italy.
authors.forename: Fabiana
authors.initials: F
authors.lastname: Scotto
authors.affiliation: Provincial District of Ravenna, Arpae Emilia-Romagna, Via Alberoni, 17/19, 48121, Ravenna, Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Zigola
authors.affiliation: Department of Science and HighTechnology, Università degli Studi dell'Insubria, Via Valleggio 11, 22100, Como, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Cattaneo
authors.affiliation: Department of Science and HighTechnology, Università degli Studi dell'Insubria, Via Valleggio 11, 22100, Como, Italy.
authors.forename: Domenico Maria
authors.initials: DM
authors.lastname: Cavallo
authors.affiliation: Regional Centre for Environment and Health, Arpae Emilia-Romagna, Via Begarelli, 13, 41121, Modena, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Lauriola
authors.affiliation: Regional Centre for Urban Areas, Arpae Emilia-Romagna, Via Rocchi, 19, 40138, Bologna, Italy.
authors.forename: Vanes
authors.initials: V
authors.lastname: Poluzzi
authors.affiliation: Division of Environmental Health and Risk Management, School of Geography, Earth & Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom.
authors.forename: Roy M
authors.initials: RM
authors.lastname: Harrison
mesh_terms: D000397:Air Pollution / Q000032:analysis; D016902:Air Pollution, Indoor / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods*; D006798:Housing / Q000706:statistics & numerical data*; D006801:Humans; D007558:Italy; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis* / Q000737:chemistry*; D014887:Weather
chemical_list: D052638:Particulate Matter
keywords: Chemical components; Exposure; Fine particles; Indoor; Misclassification; Size distribution; Traffic