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The spread of SARS-CoV-2 by contact (direct or indirect) is widely accepted, but the relative importance of airborne transmission is still controversial. Probability of outdoor airborne transmission depends on several parameters, still rather uncertain: virus-laden aerosol concentrations, viability and lifetime, minimum dose necessary to transmit the disease. In this work, an estimate of outdoor concentrations in northern Italy (region Lombardia) was performed using a simple box model approach, based on an estimate of respiratory emissions, with a specific focus for the cities of Milan and Bergamo (Italy). In addition, the probability of interaction of virus-laden aerosol with pre-existing particles of different sizes was investigated. Results indicate very low (, Highlights • Concentrations of SARS-CoV-2 in outdoor air were estimated using a box model. • Probability of interactions with pre-existing aerosol particles was investigated. • Average outdoor concentration was

The recently developed Ion and Mass Balance (IMB) source apportionment methodology was applied to a traffic influenced urban aerosol, permitting the quantification of the contributions of 11 source components, or formation processes, which accounted for more than 96% of the measured aerosol mass loading. Main sources included exhaust and non-exhaust road vehicle emissions, biomass burning, secondary inorganic and organic pollutants, and primary soil and sea salt emissions. While in summer secondary carbonaceous matter is the predominant fraction, in winter biomass burning accounts, on average, for more than 40% of the PM2.5 aerosol. Comparison with Positive Matrix Factorization (PMF) showed the complementary characteristics of the two methodologies. PMF yielded 8 source profiles, including industry and oil combustion sources not discriminated by IMB. PMF is better at quantifying multiple component contributions to sources. IMB solves problems of collinearity between aerosol tracers and permits the discrimination of secondary formed pollutants.

Knowledge gaps in the optical properties of carbonaceous aerosols account for a significant fraction of the uncertainty of aerosol - light interactions in climate models. Both black carbon (BC) and brown carbon (BrC) can display a range of optical properties in ambient aerosol due to different sources and chemical transformation pathways. This study investigates the optical absorption properties of BC and BrC at an urban and a rural site in the Po Valley (Italy), a known European pollution hot spot. We observed spatial and seasonal variability of aerosol absorption coefficients, with the highest values measured in winter at the urban site of Milan (12 Mm–1 on average) and the lowest values in summer at the rural site of Motta Visconti (3 Mm–1 on average). The average aerosol Absorption Angstrom Exponent (AAE) measured during the two experiments across the 370–880 nm wavelength range was 1.1 and 1.2 at the urban and the rural site, respectively. The observed AAE values in winter (the average AAE during the two winter campaigns was 1.2) are consistent with the contribution of wood burning BrC, as confirmed by macro-tracer analysis. The BC mass absorption cross section (MACBC) did not show a specific seasonal or spatial variability across the two sites and maintained an average value of 10 ± 5 m2 g–1 at 880 nm. The optical properties of BrC, investigated off-line after extraction of organic aerosol (OA) indicate that wood burning was the dominant BrC source in winter, while secondary organic aerosol (SOA) from other anthropogenic emissions was the main source of BrC in summer.

The present study aims to investigate the role/contribution of residential combustion (using levoglucosan as a tracer of biomass combustion) during PM10 episode days registered over the Porto urban area (Portugal), in order to support air quality plans that need to be developed for this particular region. The levoglucosan and PM10 concentration values, together with the meteorological conditions (namely temperature), measured during an experimental field campaign performed in 2013, were used in this study. To this end, a wavelet-based approach is applied to (a) better quantify the coherence and dependency of these variables and (b) assess the strength of the connection between the two pollutants species (PM and levoglucosan) at different time scales. Results evidenced a high coherence/dependency between PM10 and levoglucosan values for the episodes selected (periods with exceedances of the PM10 limit values), suggesting the contribution of biomass combustion sources. The highest coherence (normalised covariance) is observed for the winter episodes and time periods of 5–10 days, which is related to the duration of the episodes selected. The summertime episode, which exhibits a negligible observed correlation between temperature and levoglucosan, is explained by the influence of forest fires that occurred within this period and region.

The contribution of natural sources to ambient air particulate matter (PM) concentrations is often not considered; however, it may be significant for certain areas and during specific periods of the year. In the framework of the AIRUSE-LIFE+ project, state-of-the-art methods have been employed for assessing the contribution of major natural sources (African dust, sea salt and forest fires) to PM concentrations, in southern European urban areas. 24 h measurements of PM10 and PM2. 5 mass and chemical composition were performed over the course of a year in five cities: Porto, Barcelona, Milan, Florence and Athens. Net African dust and sea-salt concentrations were calculated based on the methodologies proposed by the EC (SEC 2011/208). The contribution of uncontrolled forest fires was calculated through receptor modelling. Sensitivity analysis with respect to the calculation of African dust was also performed, in order to identify major parameters affecting the estimated net dust concentrations. African dust contribution to PM concentrations was more pronounced in the eastern Mediterranean, with the mean annual relative contribution to PM10 decreasing from 21 % in Athens, to 5 % in Florence, and around 2 % in Milan, Barcelona and Porto. The respective contribution to PM2. 5 was calculated equal to 14 % in Athens and from 1.3 to 2.4 % in all other cities. High seasonal variability of contributions was observed, with dust transport events occurring at different periods in the western and eastern Mediterranean basin. Sea salt was mostly related to the coarse mode and also exhibited significant seasonal variability. Sea-salt concentrations were highest in Porto, with average relative contributions equal to 12.3 % for PM10. Contributions from uncontrolled forest fires were quantified only for Porto and were low on an annual basis (1.4 and 1.9 % to PM10 and PM2. 5, respectively); nevertheless, contributions were greatly increased during events, reaching 20 and 22 % of 24 h PM10 and PM2. 5 concentrations, respectively.

This study presents a high–resolution (5 km) set of new simulations performed with CAMx v6.40 over the Po Valley area (Northern Italy), aimed to enhance organic aerosol (OA) levels prediction and to gain insight into the sensitivity of CAMx to different uncertain features of the input setup. In particular, we mainly investigated the role of (i) volatility distributions of organic emissions, (ii) parametrizations of semi– and intermediate–volatile organic compounds (S/IVOC) emissions and (iii) different aging schemes, by exploiting the latest experimental information available in the recent scientific literature. Model results were validated against two OA–specific datasets, available for both an urban site (Bologna, February 2013) and a rural one (Ispra, March 2013). We found out a remarkable performance enhancement of modelled OA levels when applying revisions in S/IVOC emission parametrizations together with the new volatility distributions, at both the validation sites. This performance enhancement is associated with a very significant improvement in secondary organic aerosol (SOA) prediction, mainly due to revised IVOC emissions. At Bologna urban site, mean fractional bias (MFB) of OA ranged from −80.1% in the worst run to −10.1% in the best one and index of agreement (IOA) from 0.52 to 0.75. Notable improvements but overall poorer metrics were found for Ispra site, where MFB ranges from −84.2% to −35% and IOA from 0.45 to 0.50. These findings indicate that organic matter in the semi– and intermediate–volatile range are most likely underestimated in official emission inventories for each main source category (i.e. biomass burning, diesel and gasoline vehicles exhaust). Finally, model results did not show a very pronounced sensitivity to aging processes, due to the low photochemical activity typically observed during winter–time. However, we give evidence that enabling aging processes for biomass burning related SOA, which is by default disabled in CAMx v6.40, can help in closing the gap between modelled and observed SOA concentrations.

The AIRUSE-LIFE+ project aims at characterizing similarities and heterogeneities in particulate matter (PM) sources and contributions in urban areas from southern Europe. Once the main PMx sources are identified, AIRUSE aims at developing and testing the efficiency of specific and non-specific measures to improve urban air quality. This article reports the results of the source apportionment of PM and PM conducted at three urban background sites (Barcelona, Florence and Milan, BCN-UB, FI-UB and MLN-UB), one suburban background site (Athens, ATH-SUB) and one traffic site (Porto, POR-TR). After collecting 1047 PM and 1116 PM 24 h samples during 12 months (from January 2013 on) simultaneously at the five cities, these were analysed for the contents of OC, EC, anions, cations, major and trace elements and levoglucosan. The USEPA PMF5 receptor model was applied to these data sets in a harmonized way for each city. The sum of vehicle exhaust (VEX) and non-exhaust (NEX) contributes between 3.9 and 10.8 μ (16-32 %) to PM and 2.3 and 9.4 μ (15-36 %) to PM, although a fraction of secondary nitrate is also traffic-related but could not be estimated. Important contributions arise from secondary particles (nitrate, sulfate and organics) in PM (37-82 %) but also in PM (40-71 %), mostly at background sites, revealing the importance of abating gaseous precursors in designing air quality plans. Biomass burning (BB) contributions vary widely, from 14-24 % of PM in POR-TR, MLN-UB and FI-UB, 7 % in ATH-SUB, to < 2 % in BCN-UB. In PM, BB is the second most important source in MLN-UB (21 %) and in POR-TR (18 %), the third one in FI-UB (21 %) and ATH-SUB (11 %), but is again negligible (< 2 %) in BCN-UB. This large variability among cities is mostly due to the degree of penetration of biomass for residential heating. In Barcelona natural gas is very well supplied across the city and is used as fuel in 96 % of homes, while in other cities, PM levels increase on an annual basis by 1-9 μ due to biomass burning influence. Other significant sources are the following. - Local dust, 7-12 % of PM10 at SUB and UB sites and 19 % at the TR site, revealing a contribution from road dust resuspension. In PM2.5 percentages decrease to 2-7 % at SUB-UB sites and 15 % at the TR site. - Industry, mainly metallurgy, contributing 4-11 % of PM (5-12 % in PM), but only at BCN-UB, POR-TR and MLN-UB. No clear impact of industrial emissions was found in FI-UB and ATH-SUB. - Natural contributions from sea salt (13 % of PM10 in POR-TR, but only 2-7 % in the other cities) and Saharan dust (14 % in ATH-SUB, but less than 4 % in the other cities). During high pollution days, the largest sources (i.e. excluding secondary aerosol factors) of PM10 and PM2.5 are VEX + NEX in BCN-UB (27-22 %) and POR-TR (31-33 %), BB in FI-UB (30-33 %) and MLN-UB (35-26 %) and Saharan dust in ATH-SUB (52-45 %). During those days, there are also quite important industrial contributions in BCN-UB (17-18 %) and local dust in POR-TR (28-20 %)., Acknowledgements.This work was funded by the AIRUSE LIFE+(ENV/ES/584) EU project. Fulvio Amato is a beneficiary of theJuan de la Cierva postdoctoral grant (JCI-2012-13473) from theSpanish Ministry of Economy and Competitiveness. Danilo Custó-dio acknowledges the doctoral fellowship SFRH/BD/76283/2011from the Portuguese Science Foundation. Support is acknowledgedto Generalitat de Catalunya 2014 SGR33 and to AXA Research Fund

Wood combustion experiments were carried out in a Portuguese woodstove to determine the effects of biofuel type, ignition technique, biomass load and cleavage, as well as secondary air supply, on the chemical composition of particles (PM 10 ). Two typical wood fuels in the Iberian Peninsula were tested: pine ( Pinus pinaster ), a softwood, and beech ( Fagus sylvatica ), a hardwood. PM 10 samples were analysed for organic and elemental carbon (OC and EC), levoglucosan and 56 elements. Total carbon (TC) represented 54–73 wt.% of the particulate mass emitted during the combustion process, regardless of wood species burned or operating condition tested. The carbonaceous component of PM 10 was dominated by OC. The OC content of PM 10 was higher when higher loads were fed into the combustion chamber, for both fuels. EC represented from 8 to 35 wt.% of the particulate mass. OC/EC ranged from 1.1 to 6.1 (avg. 3.0 ± 1.8) for pine combustion and from 1.1 to 3.4 (avg. 2.0 ± 0.8) for beech combustion. The lowest OC/EC ratios for both woods were observed for ignition from the top. Levoglucosan was found in all samples, representing from 3.7 to 7.5 wt.% and from 4.2 to 8.9 wt.% of PM 10 emitted from the combustion of pine and beech, respectively. The use of low loads of fuel generated high amounts of levoglucosan either for pine or beech. Altogether, trace elements obtained by ICP-MS and ICP-AES comprised from 0.46 wt.% to 1.41 wt.% and from 0.87 wt.% to 2.36 wt.% of the PM 10 mass for pine and beech combustion, respectively. Among elements, K, Ca, Na, Mg, Fe and Al contributed to more than 75% of the total ICP-MS mass. Potassium was the major element in almost all PM 10 samples.

Air pollution represents a critical issue in Milan urban area (Northern Italy). Here, the levels of fine particles increase, overcoming the legal limits, mostly in wintertime, due to favourable calm weather conditions and large heating and vehicular traffic emissions. The main goal of this work is to quantify the aerosol removal effect due to precipitation at the ground. At first, the scavenging coefficients have been calculated for aerosol particles with diameter between 0.25 and 3 μm. The average values of this coefficient vary between 2 × 10 - 5 and 5 × 10 - 5 s −1 . Then, the aerosol removal induced separately by precipitation and wind have been compared through the introduction of a removal index. As a matter of fact, while precipitation leads to a proper wet scavenging of the particles from the atmosphere, high wind speeds cause enhanced particle dispersion and dilution, that locally bring to a tangible decrease of aerosol particles’ number. The removal triggered by these two forcings showed comparable average values, but different trends. The removal efficiency of precipitation lightly increases with the increase of particle diameters and vice versa happens with strong winds.

Particle number size distributions (PNSDs) have been collected periodically in Milan urban area, Italy, during 2011 and 2012 in winter and summer months. Moreover, comparable PNSD measurements were carried out in the rural mountain site of Oga-San Colombano (2250 m a.s.l.), Italy, during February 2005 and August 2011. The aerosol data have been measured through the use of Optical Particle Counters in the size range 0.3–25 µm, mainly belonging to the coarse mode (PMcoarse), with a time resolution of one minute. The comparison of the PNSDs collected in the two sites has been done in terms of total number concentration, showing higher numbers in Milan (often exceeding 103 cm−3 in winter season) compared to Oga-San Colombano (not greater than 2 ∙ 102 cm−3), as expected. The skewness-kurtosis plane has been used in order to provide a synoptic view, and select the best distribution family describing the empirical PNSD pattern. The four-parameter Johnson SB (JSB) distribution has been tested for this aim, due to its great flexibility and ability of assuming different shapes. The PNSD pattern has been found to be generally invariant under site and season changes. Nevertheless, several PNSDs belonging to Milan winter season (generally more than 30 %) clearly deviate from the standard empirical pattern. The seasonal increase of the concentration of primary aerosols due to combustion processes in winter and the influence of weather variables, such as precipitation and wind speed, throughout the year, could be considered plausible explanations of PNSD dynamics.

This work discusses the source apportionment results produced by receptor and chemistry-transport modelling for PM2.5 in Northern Italy, selected as case study due to its very critical conditions. Receptor modelling was performed using the Chemical Mass Balance model, while source oriented analysis by means of the CAMx chemistry transport model. Models shared the same source profiles, mostly based on local data. CMB showed a better reconstruction of the mass closure, while CAMx systematically underestimated cold season concentrations. Nevertheless both models provided the same source ranking at several receptors. According to CMB results, the most relevant contributions during the cold season, ranging around 10 μg m −3 , were yielded by road transport, domestic heating and ammonium nitrate. CAMx provided similar results for the secondary sources, while systematically underestimated road transport and domestic heating. A similar behaviour was observed during the summer season. The main discrepancies between the models were: the questionable results from CMB at some receptors, missing the road transport contribution, clearly pointed out by CAMx/PSAT; the ability of CAMx/PSAT to apportion the contribution of sources sharing similar profiles and strongly correlated such as CI and SI vehicles, altogether recognized as traffic source by CMB; the ability of CAMx/PSAT to identify the contribution of secondary PM deriving from complex chemical transformation, such as anthropogenic and biogenic SOA. Finally, the comparison of specific source contribution pointed out that CAMx missed the reconstruction of the road transport contribution to the OC, mostly as a consequence of deficiencies in the emission inventories concerning the primary OC in the cold season and the concurrent underestimation of emissions and secondary OC formation in the warm season.

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Traditional aerosol mechanisms underestimate the observed organic aerosol concentration, especially due to the lack of information on secondary organic aerosol (SOA) formation and processing. In this study we evaluate the chemical and transport model CAMx during a one-month in winter (February 2013) over a 5 km resolution domain, covering the whole Po valley (Northern Italy). This works aims at investigating the effects of chemical and physical atmospheric processing on modelling results and, in particular, to evaluate the CAMx sensitivity to organic aerosol (OA) modelling schemes: we will compare the recent 1.5D-VBS algorithm (CAMx-VBS) with the traditional Odum 2-product model (CAMx-SOAP). Additionally, the thorough diagnostic analysis of the reproduction of meteorology, precursors and aerosol components was intended to point put strength and weaknesses of the modelling system and address its improvement. Firstly, we evaluate model performance for criteria PM concentration. PM10 concentration was underestimated both by CAMx-SOAP and even more by CAMx-VBS, with the latter showing a bias ranging between −4.7 and −7.1 μg m−3. PM2.5 model performance was to some extent better than PM10, showing a mean bias ranging between −0.5 μg m−3 at rural sites and −5.5 μg m−3 at urban and suburban sites. CAMx performance for OA was clearly worse than for the other PM compounds (negative bias ranging between −40% and −75%). The comparisons of model results with OA sources (identified by PMF analysis) shows that the VBS scheme underestimates freshly emitted organic aerosol while SOAP overestimates. The VBS scheme correctly reproduces biomass burning (BBOA) contributions to primary OA concentrations (POA). In contrast VBS slightly underestimates the contribution from fossil-fuel combustion (HOA), indicating that POA emissions related to road transport are either underestimated or associated to higher volatility classes. The VBS scheme under-predictes the SOA too, but to a lesser extent than CAMx-SOAP. SOA underestimation can be related to corresponding underestimation of either aging processes or precursor emissions. This indicates that improvements in the emission inventories for semi- and intermediate-volatility organic compounds are needed for further progress in this area. Finally, the comparison between modelled and observed SOA sources points out the urgency to include processing of OA in particle water phase into SOA formation mechanisms, to reconcile model results and observations.

An interlaboratory comparison was performed to evaluate the analytical methods for quantification of anhydrosugars - levoglucosan, mannosan, galactosan - and biosugars - arabitol, glucose and mannitol - in atmospheric aerosol. The performance of 10 laboratories in Italy currently involved in such analyses was investigated on twenty-six PM (particulate matter) ambient filters, three synthetic PM filters and three aqueous standard solutions. An acceptable interlaboratory variability was found, determined as the mean relative standard deviation (RSD%) of the results from the participating laboratories, with the mean RSD% values ranging from 25% to 46% and decreasing with increasing sugar concentration. The investigated methods show good accuracy, evaluated as the percentage error (ε%) related to mean values, since method biases ranged within ±20% for most of the analytes measured in the different laboratories. The detailed investigation (ANOVA analysis at p 0.05) of the contribution of each laboratory to the total variability and the measurement accuracy shows that comparable results are generated by the different methods, despite the great diversity in terms of extraction conditions, chromatographic separation - more recent LC (liquid chromatography) and EC (exchange chromatography) methods compared to more widespread GC (gas chromatography) - and detection systems, namely PAD (pulsed amperometric detection) or mass spectrometry.

Three years of particle phase B(a)P air concentration measurements in 13 sites in Lombardy (Italy) and a detailed emission inventory at the municipal scale for the whole region were used to infer the contribution of different sources to B(a)P atmospheric levels. The analyses of the weekly and monthly profiles of B(a)P concentrations, the cluster analysis and the comparison between the B(a)P/PM10 ratios in ambient air and in the emissions allowed identifying wood burning in small residential appliances as the key source for all the sites, except for those located in Milan. The highest values of the average B(a)P concentrations were not found in the wider urban areas, where in general the highest PM10 levels were registered. Regarding the seasonal variability, a marked reduction of both B(a)P concentrations and B(a)P/PM10 ratios was observed in the summer season. The cluster analysis of PM10 and B(a)P concentrations showed that the two pollutants tend to have a separate pattern; moreover the cluster analysis of B(a)P/PM10 ratios showed that the trend of this ratio split the stations depending on their location: plain area, piedmont and valley zones, and mountain sites. The dominance of the wood combustion highlighted by the emission inventory, originating from the residential sector and from pizzerias in the city of Milan, is consistent with the findings of other studies based on a source apportionment approach or air quality modeling, although some patterns of ambient B(a)P concentrations in one site were not adequately explained by the emission sources included in the emission inventory.

An extensive measurement campaign was conducted in the Milan subway system in order to investigate PM10 concentrations, to determine its physical and elemental composition, its origins, and to attempt to quantify source contributions. The Milan subway system includes three lines and stations typically consist of two underground levels: an intermediate floor (mezzanine) where the turnstiles for accessing the platform are located, and a platform level, one floor down. Measurements were performed in two stations for each line, and both microenvironments (platform and mezzanine) were investigated in all cases. PM10 samples were collected at all twelve sites over three daily periods for nine consecutive days at each site. Particle number concentrations were also measured with Optical Particle Counters (OPC) and size-number distributions were determined. X-ray fluorescence analysis was also performed on the samples to determine element concentrations. The results indicate PM sources related with train operations as the dominant impact on particulate concentrations. Average weekday PM10 concentrations between 105 and 283 m gm � 3 were observed at the platform level, while average ambient concentrations of 36 m gm �3 were observed. Fe, Ba, Sb, Mn and Cu were found to be significantly enriched. Metal particles, occurring mostly in the range of diameters between 1 and 5 mm, and therefore likely originating from mechanical processes, account for most of the PM10 mass at the platform level. Wheel, brake and track wear are found to contribute 40e73% of total PM10 mass and electric cable wear (Cu and Zn oxides) 2%e3%. Concentrations measured on the mezzanine levels are intermediate between those found in ambient air and on the platform level, with average daytime PM10 values ranging from 50 to 80 m gm �3 . The situation observed on the mezzanine can well be described through an appropriate mixing of ambient and platform level air. A decreasing, albeit still significant, impact from internal sources is observed, with particulate from wheel, brake and track wear contributing an average of 2e25%, and electric cable wear 0.5e1.2%, to total PM10 mass.

This chapter reports the results of the PM10 and PM2.5 source apportionment at 3 urban background sites (Barcelona, Florence and Milan, BCN-UB, FI-UB, MLN-UB) 1 suburban background site (Athens, ATH-SUB) and 1 traffic site (Porto, POR-TR). Road traffic (sum of vehicle exhaust, non-exhaust and traffic-related secondary nitrate) is the most important source of PM10 (23–38% at all sites) and PM2.5 (22–39%, except for ATH-SUB and BCN-UB). The second most important source of PM10 (20–26%) is secondary sulphate/OC at BCN-UB, FI-UB and ATH-SUB, while it represents 10–14% in MLN-UB and POR-TR. The relative importance of this source is higher in PM2.5 (19–37% at SUB-UB sites). Biomass burning contributions vary widely from 14–24% of PM10 in POR-TR, MLN-UB and FI-UB, 7% in ATH-SUB to

Aerosol number concentration and size distributions in the 10–20,000 nm size range were measured using a Differential Mobility Particle Sizer (DMPS) and an Optical Particle Counter (OPC) at an urban background site. Daily patterns of the total particle (TP), ultrafine (UFP, Dp

Interest in renewable energy sources has increased in recent years due to environmental concerns about global warming and air pollution, reduced costs and improved efficiency of technologies. Under the European Union (EU) energy directive, biomass is a suitable renewable source. The aim of this study was to experimentally quantify and characterize the emission of particulate matter (PM2.5) resulting from the combustion of two biomass fuels (chipped residual biomass from pine and eucalypt), in a pilot-scale bubbling fluidized bed (BFB) combustor under distinct operating conditions. The variables evaluated were the stoichiometry and, in the case of eucalypt, the leaching of the fuel. The CO and PM2.5 emission factors were lower when the stoichiometry used in the experiments was higher (0.33±0.1 g CO/kg and 16.8±1.0 mg PM2.5/kg, dry gases). The treatment of the fuel by leaching before its combustion has shown to promote higher PM2.5 emissions (55.2±2.5 mg/kg, as burned). Organic and elemental carbon represented 3.1 to 30 wt.% of the particle mass, while carbonate (CO3(2-)) accounted for between 2.3 and 8.5 wt.%. The particulate mass was mainly composed of inorganic matter (71% to 86% of the PM2.5 mass). Compared to residential stoves, BFB combustion generated very high mass fractions of inorganic elements. Chloride was the water soluble ion in higher concentration in the PM2.5 emitted by the combustion of eucalypt, while calcium was the dominant water soluble ion in the case of pine.

Seven fuels (four types of wood pellets and three agro-fuels) were tested in an automatic pellet stove (9.5 kWth) in order to determine emission factors (EFs) of gaseous compounds, such as carbon monoxide (CO), methane (CH4), formaldehyde (HCHO), and total organic carbon (TOC). Particulate matter (PM10) EFs and the corresponding chemical compositions for each fuel were also obtained. Samples were analysed for organic carbon (OC) and elemental carbon (EC), anhydrosugars and 57 chemical elements. The fuel type clearly affected the gaseous and particulate emissions. The CO EFs ranged from 90.9 ± 19.3 (pellets type IV) to 1480 ± 125 mg MJ−1 (olive pit). Wood pellets presented the lowest TOC emission factor among all fuels. HCHO and CH4 EFs ranged from 1.01 ± 0.11 to 36.9 ± 6.3 mg MJ−1 and from 0.23 ± 0.03 to 28.7 ± 5.7 mg MJ−1, respectively. Olive pit was the fuel with highest emissions of these volatile organic compounds. The PM10 EFs ranged from 26.6 ± 3.14 to 169 ± 23.6 mg MJ−1. The lowest PM10 emission factor was found for wood pellets type I (fuel with low ash content), whist the highest was observed during the combustion of an agricultural fuel (olive pit). The OC content of PM10 ranged from 8 wt.% (pellets type III) to 29 wt.% (olive pit). Variable EC particle mass fractions, ranging from 3 wt.% (olive pit) to 47 wt.% (shell of pine nuts), were also observed. The carbonaceous content of particulate matter was lower than that reported previously during the combustion of several wood fuels in traditional woodstoves and fireplaces. Levoglucosan was the most abundant anhydrosugar, comprising 0.02–3.03 wt.% of the particle mass. Mannosan and galactosan were not detected in almost all samples. Elements represented 11–32 wt.% of the PM10 mass emitted, showing great variability depending on the type of biofuel used.

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A method is described that enables the user to evaluate the effects on urban air quality of reduction measures imposed on vehicular traffic and operation of building heating systems. The method involves the use of mathematical models for the calculation of urban pollutant (CO and NOx) emissions and concentrations. The models for the calculation of emissions from traffic sources and from distributed heating furnaces are based on a detailed inventory of the sources and their characteristics, and calculate the area emissions (mass of pollutant emitted per unit area) over the territory of interest. The dispersion models used for the calculation of pollutant concentrations at selected receptor points are modified versions of the EPA APRAC3 and ISC-ST models. A number of possible traffic and heating reduction scenarios for the Milan urban area are discussed as applications of the method.

This study describes an application of the APRAC3 (Air Pollution Research Advisory Committee Version 3) model of the EPA UNAMAP (User's Network for Applied Modeling of Air Pollution) system to the calculation of the CO and NOx air concentrations from motor vehicle emissions in the Milan urban area. The local micrometeorological parameters were measured by an automatic monitoring network; traffic flows and speed were evaluated through a traffic assignment model; motor vehicle composition and hourly distribution throughout the day were determined by the Milan Urban Police measurements; the emission factors were estimated from R. Joumard's experimental data. The calculated hourly concentrations of CO and NOx for the average day were compared with those measured at six points fortwo months, June and September 1989. The normalized mean-square errors obtained for the monthly average hourly concentrations were generally below 0.2 and for monthly average concentrations were below 0.1. The results of the comparison between calculated and measured concentrations suggested the use of APRAC3 for air quality analysis in urban transportation planning in Milan.

Municipal solid waste incinerator (MSWI) fly ash was investigated to study metal distribution on the particle surface. A detailed investigation into the distribution of chlorine, copper, iron, and zinc was carried out by electron microscopy coupled with X-ray fluorescence spectroscopy. Compositional and leaching test data were used to identify the correlation of significant variables and to formulate a hypothesis about metals speciation. The presence of copper chloride, iron, and zinc oxides was inferred. The iron and zinc accumulation in the submicron nuclei indicates that these metals came from the condensation of volatile species. As far as concerns copper, morphological data together with the element correlation study suggest that this element accumulates on particles involved in heterogeneous condensation processes. Furthermore, during such processes, particles of small size containing copper are formed.

INTRODUCTION Polyciclic aromatic hydrocarbons (PAHs) are produced by high-temperature reactions such as incomplete combustion and pyrolysis of fossil fuels and other organic materials. Studies have estimated that mobile sources are the major contributors to PAHs content of urban and suburban aerosol (Nielsen T., 1996). High concentrations of PM10 are associated to adverse health effects and PAHs, primarily adsorbed to fine particles, account for most of the mutagenic potency that can be assigned to specific compounds (Hanningan et al., 1998). PAHs can be found both in the gas and in the particulate phase, and for more volatile PAHs this is a function of temperature: PAHs with a higher molecular weight, which are more toxic, are always primarily associated with particulate phase (e.g B[a]P more than 90% in the particulate phase) (Odabasi M., 1999)

In several studies, investigators have reported associations among air pollution, weather, and daily deaths, usually from all causes. In the current study, we focused on the difference in lag time between exposure to total suspended particulates or extreme weather and cause-specific mortality in an effort to understand the potential underlying mechanism. We used a robust Poisson regression in a generalized additive model to investigate the association between air pollution and daily mortality. We used a loess smooth function to model season, weather, and humidity; indicator variables for hot days were also used. To examine the relationship in a currently meaningful range, we excluded all days with a total suspended particulate concentration higher than 200 microg/m3. We found a significant association on the concurrent day, both for respiratory infection deaths (11% increase/100 microg/m3 increase in total suspended particulate; 95% confidence interval = 5, 17) and for heart-failure deaths (7% increase; 95% confidence interval = 3, 11). The associations with myocardial infarction (i.e., 10% increase; 95% confidence interval = 3, 18) and chronic obstructive pulmonary disease (12% increase, 95% confidence interval = 6, 17) were found for the means of 3 and 4 d prior to death. We observed an effect of cold weather at lag 1 for respiratory infections and an effect of hot weather at lag 0 for heart failure and myocardial infarctions. The association for all causes and cause-specific deaths was almost identical to that noted previously in Philadelphia, Pennsylvania. Smoothed functions of total suspended particulates suggested a higher slope at lower concentrations, and this finding may account for differences noted between European and U.S. studies. Given that both the dependence between weather and daily mortality and the lag between exposure and death varies by cause of death, analyses by specific causes of death would be very useful in the future.

In the Province of Varese several operations have been carried out in the last two years for the removal or overcovering of asbestos-cement roofings. The present study assessed the level of exposure of the operators to inhalable asbestos fibres. The concentrations of asbestos fibres were determined by optic and electronic microscope analysis: the analyses showed the presence of mixtures of chrysotile and amosite in varying proportions. The exposure levels were correlated with the work procedures. In handling materials, there is not only fibre dispersion but sometimes also the production of asbestos-cement fragments, which can release inhalable fibres several days later. In order to limit both personal and environmental risk, it is essential to observe the rules of caution and good practice.

An evaluation of environmental data for use in epidemiologic studies has been made, based on the experience of air pollution monitoring networks management. Univocal criteria are necessary for networks project and their management to have comparable data, underlining the importance of Quality Insurance Control Laboratories. Data elaborations to verify the Air Quality Standards observance are often not sufficient for exposure assessment. Some methods to explain to general populations environmental phenomena are shown from an experience carried out recently in Reggio Emilia and Milan. Finally, it is emphasised the importance to establish a cooperation between air pollution network managers and the data users to understand the representativeness and the correct use of data from monitoring systems.

Short term effects of air pollutant levels on daily mortality were studied, using time series approach, in Milan from the year 1980 to 1989. The Poisson regression with autocorrelated residuals was applied. This paper reports preliminary results of the analyses on the association between total daily number of deaths and the 24h mean concentrations, on the same day, for two air pollutants: sulphur dioxide and total suspended particulate. A positive and curvilinear relation (with a logarithmic shape) has been found between total daily mortality and concentration levels for each pollutant. This result confirm a steeper increase in mortality at low concentrations, lower than the international standards in use at the moment.

The radioactive cloud released during the Chernobyl accident reached the Po Plain and Lombardy in the night of April 30, 1986; the cloud remained in the northern Italian skies for a few days and then disappeared either dispersed by winds or washed by rains. The evidence in the atmosphere of radionuclides as tellurium, iodine, cesium was promply observed by the Istituto di Fisica. The intense rain, in the first week of May, washed the radioactivity and the fallout contaminated the land, soil, grass and vegetables. The present work concerns the overall contamination of the Northern Italy territory and in particular the radioactive fallout in the Alpine region. Samples of soil have been measured at the gamma-spectroscope; a linear correlation is found between the radionuclide concentration in soil samples and the rain intensity, when appropriate deposition models are considered. A number of measurements has been done on Lake Como ecosystem: sediments, plankton, fishes and the overall fallout in the lake area have been investigated.

Biomass burning (BB) is a significant source of atmospheric particles in many parts of the world. Whereas many studies have demonstrated the importance of BB emissions in central and northern Europe, especially in rural areas, its impact in urban air quality of southern European countries has been sparsely investigated. In this study, highly time resolved multi-wavelength absorption coefficients together with levoglucosan (BB tracer) mass concentrations were combined to apportion carbonaceous aerosol sources. The Aethalometer model takes advantage of the different spectral behaviour of BB and fossil fuel (FF) combustion aerosols. The model was found to be more sensitive to the assumed value of the aerosol Ångström exponent (AAE) for FF (AAEff) than to the AAE for BB (AAEbb). As result of various sensitivity tests the model was optimized with AAEff = 1.1 and AAEbb = 2. The Aethalometer model and levoglucosan tracer estimates were in good agreement. The Aethalometer model was further applied to data from three sites in Granada urban area to evaluate the spatial variation of CMff and CMbb (carbonaceous matter from FF or BB origin, respectively) concentrations within the city. The results showed that CMbb was lower in the city centre while it has an unexpected profound impact on the CM levels measured in the suburbs (about 40%). Analysis of BB tracers with respect to wind speed suggested that BB was dominated by sources outside the city, to the west in a rural area. Distinguishing whether it corresponds to agricultural waste burning or with biomass burning for domestic heating was not possible. This study also shows that although traffic restrictions measures contribute to reduce carbonaceous concentrations, the extent of the reduction is very local. Other sources such as BB, which can contribute to CM as much as traffic emissions, should be targeted to reduce air pollution., This research was partially supported by the Andalusia Regional Government through projects P10-RNM-6299 and P12-RNM-2409, by the Spanish Ministry of Economy and Competitiveness and FEDER through project CGL2013_45410-R; by EUREKA and the Slovenian Ministry of Economic Development and Technology grants (Eurostars grant E!4825 FC Aeth, JR-KROP grant 3211-11-000519); and by European Union's Horizon 2020 Research and Innovation Programme under grant agreement No. 654109, ACTRIS-2. The authors would like to thank Air Quality Service from Junta de Andalucía (Consejería de Medio Ambiente y Ordenación del Territorio) and Vicerrectorado de Política Científica e Investigación from the University of Granada for their support in the installation of the Aethalometer at PC and GV, respectively., G. Titos was partially funded by Programa del Plan Propio de Investigación “Contrato Puente” of the University of Granada and by the Spanish Ministry of Economy and Competitiveness under postdoctoral program Juan de la Cierva – Formación (FJCI-2014-20819).