First Results of the “Carbonaceous Aerosol in Rome and Environs (CARE)” Experiment: Beyond Current Standards for PM10

Abstract

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 PM 1 components, elemental composition, wavelength-dependent optical properties, and atmospheric turbulence; (ii) 24-h measurements of PM 10 and PM 2.5 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 PM 10 (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 PM 10 and PM 2.5 with regard to particle composition and size distribution, and data averaging period. Our results reinforce existing concerns about the toxicity of carbonaceous aerosols, suppo...

Review of PM Oxidative Potential Measured with Acellular Assays in Urban and Rural Sites across Italy

“…The formed DCF can be easily measured by fluorescence at the excitation and emission wavelengths of 485 and 530 nm, respectively. The ROS concentration may be then calculated in terms of H 2 O 2 equivalent [21,25,26,33].…”

“…OP of PM 2.5 samples in some Italian cities were also measured as a part of more general studies concerning different locations over Europe. Rome was included in a study that measured OP DTT in 2010 [20] and also in a work carried out in February 2017 to measure OP DCHF of particles collected using PILS system [21]. Two studies measured OP AA and OP GSH of fine PM at Turin, a big industrial city (~900,000 inhabitants) located on the Western side of the Po Plain [19,31] and one of them, concerning 20 European sites over one year, also included smaller city Pavia (~70,000 inhabitants) [31].…”

“…). The acellular version of the 2 ,7 -dichlorodfluorescein (DCFH) assay uses the enzymatic production of the fluorescent probe largely used for the evaluation of oxidative stress in living cells.The present work summarizes the PM oxidative properties up to date measured in Italy using OP acellular assays, with the aim of giving a general insight of PM OP across the Italian territory, that has not been reported yet, in spite of the increasing number of OP measurements carried out in Europe [6,[19][20][21][22]. In addition, the study reviews the association described in previous studies between OP from different assays with several inorganic ad organic components, that effect PM oxidative properties, i.e., metals, ions, and carbonaceous components.…”

Does Air Pollution Influence COVID-19 Outbreaks?

“…oxygen-free radical-generating activity, DNA oxidative damage, mutagenicity, and the stimulation of pro-inflammatory responses, are currently unclear. Indeed, particle size matters, and it is important to consider the role of ultrafine particles (particles with aerodynamic diameters smaller than 100 nm) on health outcomes [11,12]. The role of chemical composition influences ecotoxicity, cytotoxicity, and genotoxicity in different ways, so that different biological outcomes are expected even in cases of similar number and mass concentrations [13].…”

Carbonaceous Aerosols in the Atmosphere

“…Vehicle tailpipe emissions and biomass burning are seen to influence the oxidative potential of PM. Finally, the question of aerosol toxicity was also addressed (among other questions) by the CARE experiment [37]. In an integrative approach, this study addresses air quality, health and climate implications of aerosol pollution.…”