First results of the "Carbonaceous Aerosol in Rome and Environs (CARE)" Experiment: Beyond current standards for PM10

In February 2017 the "Carbonaceous Aerosol in Rome and Environs (CARE)" experiment was carried out in downtown Rome to address the following specific questions: what is the color, size, composition, and toxicity of the carbonaceous aerosol in the Mediterranean urban background area of Rome? The motivation of this experiment is the lack of understanding of what aerosol types are responsible for the severe risks to human health posed by particulate matter (PM) pollution, and how carbonaceous aerosols influence radiative balance. Physicochemical properties of the carbonaceous aerosol were characterised, and relevant toxicological variables assessed. The aerosol characterisation includes: (i) measurements with high time resolution (min to 1-2 h) at a fixed location of black carbon (eBC), elemental carbon (EC), organic carbon (OC), particle number size distribution (0.008-10 μm), major non refractory PM1 components, elemental composition, wavelength-dependent optical properties, and atmospheric turbulence; (ii) 24-h measurements of PM10 and PM2.5 mass concentration, water soluble OC and brown carbon (BrC), and levoglucosan; (iii) mobile measurements of eBC and size distribution around the study area, with computational fluid dynamics modeling; (iv) characterisation of road dust emissions and their EC and OC content. The toxicological assessment includes: (i) preliminary evaluation of the potential impact of ultrafine particles on lung epithelia cells (cultured at the air liquid interface and directly exposed to particles); (ii) assessment of the oxidative stress induced by carbonaceous aerosols; (iii) assessment of particle size dependent number doses deposited in different regions of the human body; (iv) PAHs biomonitoring (from the participants into the mobile measurements). The first experimental results of the CARE experiment are presented in this paper. The objective here is to provide baseline levels of carbonaceous aerosols for Rome, and to address future research directions. First, we found that BC and EC mass concentration in Rome are larger than those measured in similar urban areas across Europe (the urban background mass concentration of eBC in Rome in winter being on average 2.6 ± 2.5 μg · m-3, mean eBC at the peak level hour being 5.2 (95% CI = 5.0-5.5) μg · m-3 ). Then, we discussed significant variations of carbonaceous aerosol properties occurring with time scales of minutes, and questioned on the data averaging period used in current air quality standard for PM10 (24-h). Third, we showed that the oxidative potential induced by aerosol depends on particle size and composition, the effects of toxicity being higher with lower mass concentrations and smaller particle size. Albeit this is a preliminary analysis, findings reinforce the need for an urgent update of existing air quality standards for PM10 and PM2.5 with regard to particle composition and size distribution, and data averaging period. Our results reinforce existing concerns about the toxicity of carbonaceous aerosols, support the existing evidence indicating that particle size distribution and composition may play a role in the generation of this toxicity, and remark the need to consider a shorter averaging period ( < 1 h) in these new standards. © 2017 by the authors.

1 CNR-ISAC—Italian National Research Council, Institute of Atmospheric Science and Climate, via Fosso del Cavaliere 100, 00133 Rome, Italy; [email protected] (S.A.); [email protected] (F.B.); [email protected] (R.B.); [email protected] (G.C.); [email protected] (S.C.); [email protected] (A.C.); [email protected] (A.D.I.); [email protected] (L.D.L.); [email protected] (I.P.); [email protected] (G.P.G.) Leibniz Institute for Tropospheric Research, Permoserstrasse 15, 04318 Leipzig, Germany; [email protected] (H.A.); [email protected] (K.W.); [email protected] (A.W.) Cultex Laboratories GmbH Feodor-Lynen-Straße 21, 04318 Hannover, Germany; [email protected] INAIL ex-ISPESL, via Urbana 167, 00184 Rome, Italy; [email protected] (P.A.); [email protected] (M.M.); [email protected] (G.T.) Department of Agricultural, Environmental and Food Sciences, University of Molise, 86100 Campobasso, Italy; [email protected] Institute of Environmental Assessment and Water Research (IDÆA), Spanish National Research Council (CSIC), 08034 Barcelona, Spain; [email protected] (F.A.); [email protected] (X.Q.) ENEA SSPT-MET-INAT, Via Martiri di Monte Sole 4, 40129 Bologna, Italy; [email protected] (M.B.); [email protected] (M.G.G.); [email protected] (M.G.); [email protected] (A.M.); [email protected] (E.P.); [email protected] (G.Z.) Department of Physics, Università degli Studi di Milano and INFN-Milan, 20133 Milan, Italy; [email protected] (V.B.); [email protected] (G.V.); [email protected] (S.V.); [email protected] (R.V.) INFN, National Institute of Nuclear Physics, Florence, 50019 Sesto Fiorentino, Italy; [email protected] (G.C.); [email protected] (F.L.); [email protected] (S.N.) Department of Chemistry, “Sapienza” University, Rome, P.le A. Moro 5, 00185 Rome, Italy; [email protected] (S.C.); [email protected] (D.F.); [email protected] (G.S.) ENEA SSPT-TECS-BIORISC Via Anguillarese, 00123 Rome, Italy; [email protected] DEIM—Industrial Engineering School, University of Tuscia, Largo dell’Università snc, 01100 Viterbo, Italy; [email protected] (A.F.); [email protected] (S.U.) CNR-ISAC—Italian National Research Council, Institute of Atmospheric Science and Climate, via Gobetti 101, 40129 Bologna, Italy; [email protected] (M.C.F.); [email protected] (S.G.); [email protected] (F.V.) CNR-IIA—Italian National Research Council, Institute of Atmospheric Pollution Research, Monterotondo Stazione, via Salaria km 29300, CP10, 00015 Rome, Italy; [email protected] (M.M.); [email protected] (C.P.) Dipartimento di Scienze Agrarie, Forestali e Alimentari (DISAFA), Università degli Studi di Torino, Grugliasco, 10095 Torino, Italy

Peer reviewed