title: Determinants of aerosol lung-deposited surface area variation in an urban environment.
abstract: Ultrafine particles are characterized by a high surface area per mass. Particle surface has been reported to play a significant role in determining the toxicological activity of ultrafine particles. In light of this potential role, the time variation of lung deposited surface area (LDSA) concentrations in the alveolar region was studied at the urban background environment of Barcelona (Spain), aiming to asses which processes and sources govern this parameter. Simultaneous data on Black Carbon (BC), total particle number (N) and particle number size distribution were correlated with LDSA. Average LDSA concentrations in Barcelona were 37 ± 26 μm(2)cm(-3), levels which seem to be characteristic for urban environments under traffic influence across Europe. Results confirm the comparability between LDSA data provided by the online monitor and those calculated based on particle size distributions (by SMPS), and reveal that LDSA concentrations are mainly influenced by particles in the size range 50-200 nm. A set of representative daily cycles for LDSA concentrations was obtained by means of a k-means cluster technique. The contribution of traffic emissions to daily patterns was evidenced in all the clusters, but was quantitatively different. Traffic events under stable atmospheric conditions increased mean hourly background LDSA concentrations up to 6 times, attaining levels higher than 200 μm(2)cm(-3). However, under warm and relatively clean atmospheric conditions, the traffic rush hour contribution to the daily LDSA mean appeared to be lower and the contribution of new urban particle formation events (by photochemically induced nucleation) was detected. These nucleation events were calculated to increase average background LDSA concentrations by 15-35% (maximum LDSA levels=45-50 μm(2)cm(-3)). Thereby, it may be concluded that in the urban background of Barcelona road traffic is the main source increasing the aerosol surface area which can deposit on critical regions of the human lung, followed by nucleation episodes.
authors.affiliation: Institute of Environmental Assessment and Water Research (IDÆA-CSIC), Barcelona, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Reche
authors.affiliation: Institute of Environmental Assessment and Water Research (IDÆA-CSIC), Barcelona, Spain.
authors.forename: Mar
authors.initials: M
authors.lastname: Viana
authors.affiliation: Institute of Environmental Assessment and Water Research (IDÆA-CSIC), Barcelona, Spain.
authors.forename: Mariola
authors.initials: M
authors.lastname: Brines
authors.affiliation: Institute of Environmental Assessment and Water Research (IDÆA-CSIC), Barcelona, Spain.
authors.forename: Noemí
authors.initials: N
authors.lastname: Pérez
authors.affiliation: National Centre for Atmospheric Science Division of Environmental Health & Risk Management School of Geography, Earth & Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
authors.forename: David
authors.initials: D
authors.lastname: Beddows
authors.affiliation: Institute of Environmental Assessment and Water Research (IDÆA-CSIC), Barcelona, Spain.
authors.forename: Andrés
authors.initials: A
authors.lastname: Alastuey
authors.affiliation: Institute of Environmental Assessment and Water Research (IDÆA-CSIC), Barcelona, Spain.
authors.forename: Xavier
authors.initials: X
authors.lastname: Querol
mesh_terms: D000336:Aerosols / Q000032:analysis*; D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000706:statistics & numerical data*; D002947:Cities / Q000706:statistics & numerical data; D004784:Environmental Monitoring; D006801:Humans; D019570:Inhalation Exposure / Q000706:statistics & numerical data*; D013030:Spain; D014505:Urban Population / Q000706:statistics & numerical data
chemical_list: D000336:Aerosols; D000393:Air Pollutants
keywords: Exhaust emissions; Lung deposition; Photochemistry; Size distribution