Characterization of particulate matter sources in an urban environment

Daily time series measurements of elements or compounds are widely used to apportion the contribution of specific sources of particulate matter concentration in the atmosphere. We present results obtained for the urban area of Genoa (Italy) based on several hundred of PM10, PM2.5 and PM1 daily samples collected in sites with different geo-morphological and urbanization characteristics. Elemental concentrations of Na to Pb were obtained through Energy Dispersive X-Ray Fluorescence (ED-XRF), and the contributions of specific sources of particulate matter (PM) concentration were apportioned through Positive Matrix Factorization (PMF). By sampling at different sites we were able to obtain, in each PM fraction, the average and stable values for the tracers of specific sources, in particular traffic (Cu, Zn, Pb) and heavy oil combustion (V, Ni). We could also identify and quote the contamination of anthropogenic PM in "natural" sources (sea, soil dust). Sampling at several sites in the same urban area allowed us to resolve local characteristics as well as to quote average values.     

The Salmonella mutagenicity of urban airborne particulate matter (PM2.5) from eight sites of the Emilia-Romagna regional monitoring network (Italy)

ARPA Emilia Romagna created, in 1997, a regional network for the continuous monitoring of the mutagenicity of PM(2.5) by short-term mutagenicity bioassays to guarantee a constant surveillance on the entire regional territory. The continuous monitoring of the PM mutagenicity provides essential information for a better understanding of the impact of air pollution on the health of the population, and allows one to better judge the efficiency of national and local efforts for urban air quality improvement (use of "green" petrol and ecodiesel, days during which traffic is prohibited, etc.). This article presents the results relating to the Network's activity between September 2000 and December 2002, on PM(2.5) fraction. The organic extracts of PM(2.5) were tested for mutagenicity using Salmonella tester strains TA98 and TA100 with and without metabolic activation (S9). The data obtained on the genotoxicity of air particulate extracts have revealed a constant presence of mutagenic substances adsorbed on particulate matter-with a prevalence of direct-acting mutagens than of promutagens-in a typical seasonal trend featuring higher levels in autumn-winter and lower in warmer periods of the year. In this work the evolution of PM(2.5) mutagenicity was compared with the particles, carbon monoxide (CO) and nitrogen dioxide (NO(2)) concentrations (monthly average); these comparisons revealed a quite good level of agreement on a local basis.     

Seasonal variation of thallium, lead, and chromium concentrations in airborne particulate matter collected in an urban area

In November 1985 a research program started, with the aim to evaluate seasonal variations in the concentrations of organic and inorganic pollutants in the atmosphere of Genoa. The program provided for the collection of samples of airborne particulate in five different areas with distinct urban characteristics. First results for chromium, lead, and thallium concentrations in an industrial and in an urban area are reported. Lead showed the highest concentration at both locations (geometric mean: 1.037 and 0.476 microgram/m3, respectively) and appeared to be little affected by seasonal variation. Private traffic was confirmed as the main source of this pollutant. Chromium and thallium geometric mean concentrations were 0.006 and 0.014 microgram/m3 in site A and 0.017 and 0.015 microgram/m3 in site B, respectively. In the urban location a good negative linear correlation was found between chromium and thallium concentration and mean ambient temperature; the domestic heating plants were suspected as important emission sources of these two compounds.     

PM(10) source characterization at urban and highway roadside locations

Levels of PM(10) were measured at two different roadside locations in the Stockholm region in Sweden, one highway south of Stockholm and one urban street canyon in the center of the city. PM(10) samples were taken during six separate campaigns over one full year, and analyzed for 29 metals, in order to help characterize sources of PM(10). Five contributing factors were identified by multivariate receptor modeling using positive matrix factorization. Factors were classified, based on their seasonal variation and published data on metal composition of different sources, as: 1) resuspension; 2) vehicle derived; 3) road salt; 4) regional combustion and 5) long-range transport. Resuspension and long-range transport were shown to be important contributors to the PM(10) levels at both sites. In fact, long-range transport was the main contributor to the PM(10) levels at the highway roadside. The vehicle source was only of major importance at the urban roadside, where it frequently contributed between 10 and 20 microg m(-3). Brake wear was an important component in the vehicle source. Vehicle exhaust was not detected as a separate source and was not identified as a major source for PM(10). To our knowledge, this is the first study identifying brake wear as a major source of PM(10) during urban driving.     

The PM2.5 and PM10 particles in urban areas of Taiwan

This study conducted an atmospheric aerosol sampling to measure the PM10 (particles < 10 microns in aerodynamic diameter) and PM2.5 (particles < 2.5 microns in aerodynamic diameter) mass concentrations from October 1996 to June 1997 in northern (Taipei), central (Taichung) and southern (Kaohsiung), the three largest cities of Taiwan. Seventy-eight samples were obtained to measure the mass concentrations of PM10 and PM2.5 from nine sampling sites. According to those results, the PM10 mass concentrations in Taipei, Taichung and Kaohsiung were 42.19, 60.99 and 77.10 micrograms/m3, respectively. The corresponding PM2.5 mass concentrations were 23.09, 39.97 and 48.47 micrograms/m3, respectively. The PM2.5 fraction accounted for 61-67% of the PM10 mass in central and southern Taiwan, but was lower (54-59%) in northern Taiwan. Some samples in which the PM2.5 fraction was overwhelmingly dominant could reach as high as 80-95% of the PM10 mass. In addition, the PM2.5, PM10 levels and PM2.5/PM10-2.5 (particles with aerodynamic diameters ranging from 2.5 to 10 microns) ratios in metropolitan Taiwan significantly fluctuated from site-to-site and over time. Moreover, ambient daily PM2.5 and PM10-2.5 mass concentrations did not correlate well with each other at most of the sampling sites, indicated that they originated from different kinds of sources and emitted variedly over time.     

The analysis of PM2.5 and associated elements and their indoor/outdoor pollution status in an urban area

In this study, elemental composition of PM2.5 and the status of indoor/outdoor pollution were investigated in a commercial building near a roadside area in Daejeon, Korea. A total of 60 parallel PM2.5 samples were collected both on the roof (outdoor) and in an indoor office of a building near a highly congested road during the spring and fall of 2008. The concentrations of 23 elements were analysed from these PM2.5 samples using instrumental neutron activation analysis. PM2.5 levels in indoor environment (47.6 ± 16.5 μg/m(3)) were noticeably higher than the outdoor levels (37.7 ± 17.2 μg/m(3)) with the I/O concentration ratio of 1.37 ± 0.33 [correlation coefficient (r) = 0.89, P < 0.001]. Principal component analysis results coincidently showed the predominance of sources such as soil dust, traffic, oil/coal combustion and road dust for both indoor and outdoor microenvironments. An isolated source in the indoor environment was assigned to environmental tobacco smoke (ETS) with high factor loading of Ce, Cl, I, K, La and Zn. The overall results of our study indicate that the sources of indoor constituents were strongly dependent on outdoor processes except for the ones affected by independent sources such as ETS. PRACTICAL IMPLICATIONS: An improved understanding of the factors affecting the indoor PM2.5 concentration levels can lead to the development of an efficient management strategy to control health risks from exposure to indoor PM2.5 and related toxic components. A comparison of our comprehensive data sets indicated that most indoor PM2.5 and associated elemental species were strongly enriched by indoor source activities along with infiltration of ambient outdoor air for a naturally ventilated building.     

Investigating the potential role of ammonia in ion chemistry of fine particulate matter formation for an urban environment

To investigate the potential role of ammonia in ion chemistry of PM_2.5 aerosol, measurements of PM_2.5 (particulate matter having aerodynamic diameter < 2.5 µm) along with its ionic speciation and gaseous pollutants (sulfur dioxide (SO₂), nitrogen oxides (NO_x), ammonia (NH₃) and nitric acid (HNO₃)) were undertaken in two seasons (summer and winter) of 2007-2008 at four sampling sites in Kanpur, an urban-industrial city in the Ganga basin, India. Mean concentrations of water-soluble ions were observed in the following order (i) summer: SO₄²⁻ (26.3 µg m^− 3) > NO₃⁻ (16.8) > NH₄⁺ (15.1) > Ca²⁺ (4.1) > Na⁺ (2.4) > K⁺ (2.1 µg m^− 3) and (ii) winter: SO₄²⁻ (28.9 µg m^− 3) > NO₃⁻ (23.0) > NH₄⁺ (16.4) > Ca²⁺(3.4) > K⁺(3.3) > Na⁺ (3.2 µg m^− 3). The mean molar ratio of NH₄⁺ to SO₄²⁻ was 2.8 ± 0.6 (mostly >2), indicated abundance of NH₃ to neutralize H₂SO₄. The excess of NH₄⁺ was inferred to be associated with NO₃⁻ and Cl⁻. Higher sulfur conversion ratio (F_s: 58%) than nitrogen conversion ratio (F_n: 39%) indicated that SO₄²⁻ was the preferred secondary species to NO₃⁻. The charge balance for the ion chemistry of PM_2.5 revealed that compounds formed from ammonia as precursor are (NH₄)₂SO₄, NH₄NO₃ and NH₄Cl. This study conclusively established that while there are higher contributions of NH₄⁺, SO₄²⁻ to PM_2.5 in summer but for nitrates (in particulate phase), it is the winter season, which is critical because of low temperatures that drives the reaction between ammonia and HNO₃ in forward direction for enhanced nitrate formation. In summary, inorganic secondary aerosol formation accounted for 30% mass of PM_2.5 and any particulate control strategy should include optimal control of primary precursor gases including ammonia.     

Atmospheric fate of phthalate esters in an urban area (Paris-France)

The atmospheric fate of six phthalate esters was investigated in the urban area of Paris (France). Total atmospheric levels (ng m-3) were as follows: DMP, 0.5; DEP, 10.7; DnBP, 22.2; BBP, 4.6; DEHP, 18.9; and DnOP, 0.5 ng m-3, showing a predominance of DnBP and next, DEHP. They are mainly present in the vapour phase, from 93.8% to 64.9%, particularly for the esters with alkyl chain length of less than six C. An inverse correlation was found between the vapour phase concentrations and the molecular weight and also a direct correlation between the vapour phase concentrations and the log [vapour pressure] of the compounds. Seasonal variations were displayed by principal component analysis (PCA), due to significant correlation between phthalate concentrations and air temperature. Rain water concentrations (ng L-1) were as follows: DMP, 116; DEP, 333; DnBP, 592; BBP, 81; DEHP, 423; and DnOP, 10. PCA analysis showed a seasonal variation of these concentrations correlated to the air temperature. The experimental water/air scavenging ratio was calculated and was in accordance with the theoretical one obtained from the vapour pressure and the Henry's law constant for each phthalate ester. The global trend was a decrease of the washout coefficient in relation with the rise of alkyl chain length. Yearly balances for rainwater and bulk deposition allowed the estimation of dry deposits that represented about half of total. Our findings highlight the major part played by particles in atmospheric deposition processes.     

Improvement of predicted fine and total particulate matter (PM) composition by applying several different chemical scenarios: a winter 2005 case study

A new method using several different chemical scenarios is developed to predict chemical composition of fine (PM2.5) and total (PM10) aerosol. This method improves the accuracy of predicted PM concentrations. The Mesoscale Model version 5 (MM5) and a 3-dimensional Eulerian chemical model (CAMx4.2) are used to predict PM2.5 and PM10 concentrations using gridded input emissions (from the Total group) over a 48-72 h time period for Christchurch (New Zealand) for winter 2005. The aerosol concentrations are obtained for four different chemical compositions (chemical scenarios) of the input aerosol emissions. PM2.5 chemical compositions are based on previous Christchurch winter studies and from observations in other countries with similar winter pollution problems, and used in CAMx4.2 to model seven winter 2005 heavy pollution episodes. The error between observed and modelled PM2.5 concentrations is based on predictions of fine aerosol that are derived from linear regression with PM10. It is used to find the minimum difference between modelled and observed PM2.5 for an observation site located in the Christchurch residential area. Combination of the chemical scenarios with analysis of the minimum error is used to create a new complex chemical scenario. The new complex scenario is used to re-calculate all pollution episodes to obtain new values of PM with minimum error compared with observed aerosol concentrations. Mean Absolute Error of the calculated PM2.5 (for all pollution episodes) decreased from 21-24 microg m(-3) to 14-16 microg m(-3) compared with observations. The chemical composition of the modelled PM2.5 is also discussed.     

Approaching PM(2.5) and PM(2.5-10) source apportionment by mass balance analysis, principal component analysis and particle size distribution

A chemical characterization was carried out for PM(2.5) and PM(2.5-10) samples collected in a suburban area and the concentrations of 12 elements were determined in 8 size segregated fractions using a Berner Impactor. Two main objectives were proposed in this work: 1) to test for closure among chemical and gravimetric measurements of PM(2.5) and PM(2.5-10) and 2) evaluate the performance of Multilinear Regression Analysis (MLRA) and Mass Balance Analysis (MBA) in the determination of source contribution to Particulate Matter (PM) concentrations. The fraction unaccounted for by chemical analysis comprised on average 17% and 34% of gravimetric PM(2.5) and PM(2.5-10), respectively. The lack of closure in PM(2.5) and PM(2.5-10) mass (i.e., constituent concentrations not adding up to gravimetrically measured) could partly result from the presence of water associated with particles and errors in the estimation of unmeasured species. MLRA and MBA showed very similar results for the temporal variation of the source contributions. However, quantitatively important discrepancies could be observed, principally due to the lack of mass closure in PM(2.5) and PM(2.5-10). Both methods indicated that the major PM(2.5) aerosol mass contributors included secondary aerosol and vehicle exhaust. In the coarse fraction, marine and mineral aerosol contributions were predominant.     

Source apportionment of PM10 and PM2.5 in Milan (Italy) using receptor modelling

In this paper a source apportionment of particulate matter pollution in the urban area of Milan (Italy) is given. Results of PM10 and PM2.5 mass and elemental concentrations from a 1-year monitoring campaign are presented. Mean annual and daily PM10 levels are compared with the limits of the EU Air Quality Directive EC/30/1999 and the results show that the limit values established would not be met in the urban area of Milan or the large surrounding area. Moreover, high levels of PM2.5 are registered and this fraction constitutes a high portion of the PM10 mass. In Milan the winter period is characterised by a high degree of air pollution due to a greater contribution of emissions and to adverse meteorological and thermodynamic conditions of the atmosphere. The application of multivariate techniques and receptor modelling (PCFA, APCFA) to the whole data-set led to the identification of the main emitting sources and to the source apportionment of PM10 and PM2.5 in Milan. The most important sources were identified as 'soil dust', 'traffic', 'industry' and 'secondary compounds' for PM10 and as 'soil dust', 'anthropogenic' and 'secondary compounds' for PM2.5, explaining the greatest part of the total variance (91% and 75%, respectively).     

PM10 composition during an intense Saharan dust transport event over Athens (Greece)

The influence of Saharan dust on the air quality of Southern European big cities became a priority during the last decade. The present study reports results on PM₁₀ monitored at an urban site at 14 m above ground level during an intense Saharan dust transport event. The elemental composition was determined by Energy Dispersive X-ray Fluorescence Spectrometry (EDXRF) for 12 elements: Si, Al, Fe, K, Ca, Mg, Ti, S, Ni, Cu, Zn and Mn. PM₁₀ concentrations exceeded the EU limit (50 μg/m³) several times during the sampling period. Simultaneous maxima have been observed for the elements of crustal origin. The concentrations of all the elements presented a common maximum, corresponding to the date where the atmosphere was heavily charged with particulate matter permanently for an interval of about 10 h. Sulfur and heavy metal concentrations were also associated to local emissions. Mineral dust represented the largest fraction of PM₁₀ reaching 79%. Seven days back trajectories have shown that the air masses arriving over Athens, originated from Western Sahara. Scanning Electron Microscopy coupled with Energy Dispersive X-ray analysis (SEM-EDX) revealed that particle agglomerates were abundant, most of them having sizes < 2 μm. Aluminosilicates were predominant in dust particles also rich in calcium which was distributed between calcite, dolomite, gypsum and Ca-Si particles. These results were consistent with the origin of the dust particles and the elemental composition results. Sulfur and heavy metals were associated to very fine particles < 1 μm.     

Physico-chemical characterization of indoor/outdoor particulate matter in two residential houses in Oslo, Norway: measurements overview and physical properties--URBAN-AEROSOL Project

Indoor/outdoor measurements have been performed in the Oslo metropolitan area during summer and winter periods (2002-2003) at two different residential houses. The objective of the measurement study was to characterize, physically and chemically, the particulate matter (PM) and gaseous pollutants associated with actual human exposure in the selected places, and their indoor/outdoor relationship. In this paper, we focus on the PM measurements and examine the relationship between the indoor and outdoor PM concentrations taking into account the ventilation rate, indoor sources and meteorological conditions. The indoor/outdoor measurements indicate the important contribution of the outdoor air to the indoor air quality and the influence of specific indoor sources such as smoking and cooking to the concentration of PM inside houses. However, no specific correlation was found between the indoor/outdoor concentration ratio and the meteorological parameters. This study provides information on the physical characteristics and the relationship of indoor to outdoor concentration of particulate matter in residential houses. Moreover, the parameters that influence this relationship are discussed. The results presented here are specific to the sampled houses and conditions used and provide data on the actual human exposure characteristics which occur in the spatial and temporal scales of the present study.     

Lipid composition of suspended particulate matter (SPM) in a southeastern blackwater stream

Suspended particulate matter (SPM) was collected seasonally for 1 yr at third- and fifth-order sites in a blackwater stream on the coastal plain in South Carolina. Fatty acids with carbon chain lengths from C(12)-C(32) were the most abundant component among the lipid classes examined with total concentrations varying from 8.5 to 60.2 microgL(-1). Unsaturated fatty acids predominated while significant concentrations of the even-chained saturated components C(24)-C(30) derived from cuticular plant waxes were also found. Concentrations of aliphatic alcohols, with carbon chain lengths between C(16) and C(30), ranged from 0.52 to 2.73 microgL(-1) and was dominated by the higher molecular weight compounds (C(22)-C(30)) derived primarily from cuticular plant waxes. Total hydrocarbon concentrations ranged from 0.35 to 5.66 microgL(-1) and showed no discernible trends with time or consistent difference between sites. The hydrocarbon assemblage observed indicates that these components are entirely of biogenic origin with no detectable anthropogenic contribution.The ratios of unsaturated to saturated fatty acids and cuticular to noncuticular fatty acids and alcohols at both stream locations indicate that the organic detritus associated with SPM collected during November and January is of more recent origin and less processed than that collected in the spring and summer months. Lipid concentrations at the third-order site generally had higher and more variable concentrations of the lipid classes compared with the fifth-order site. The ratio of saturated to unsaturated fatty acids was higher at the third-order site indicating that the organic fraction of SPM at this site was of more recent origin and less decomposed. The ratios of cuticular to noncuticular fatty acids and alcohols support this conclusion. These results indicate an export of particulate lipids of higher carbon resource quality from upstream to lower stream reaches.     

Comparison of short-term exposure to particle number, PM10 and soot concentrations on three (sub) urban locations

Recent interest has focused on the health effects of ultrafine particles because of the documented toxicity and the larger concentration contrast near motorways of UFP than for PM10 or PM2.5. There are only few studies that have measured UFP at inner-city streets simultaneously with other PM components.The aim of this study was to compare the contrast of UFP, PM₁₀ and soot measured simultaneously at 3 inner-city locations, namely a moderately busy street (15,000 vehicles/day), a city and a suburban background location.Simultaneously, measurements of particle number concentrations (PNC), PM₁₀ and soot have been conducted on three locations in and around Utrecht, a medium-sized city in the Netherlands for 20 weekdays in autumn 2008. Measurements were done for 6-h during afternoon and early evening.The mean PNC at the street location was more than 3 times higher than at the two background locations. The contrast was similar for soot concentrations. In PM₁₀ concentrations less contrast was found, namely 1.8 times. Mean PNC concentrations were poorly correlated with PM₁₀ and soot. At the street location, high temporal variation of PNC concentrations occurred within each sampling day, probably related to variations in traffic volumes, high-emission individual vehicles and wind direction. Temporal variation was smaller at the two background locations. Occasional unexplained short-term peaks occurred at the suburban background location. A relatively high correlation between PNC minute values at the two background locations was found, pointing to similar area-wide sources. Typically low correlations were found with the street locations, consistent with the dominant impact of local traffic.A large contrast between two background locations and a moderately busy urban street location was found for PNC and soot, comparable to previous studies of much busier motorways. Temporal variation of PNC was higher at the street location and uncorrelated with background variations.     

以秦皇岛北戴河新区(国华片区)为例谈城市设计

主要探讨城市设计中的城市设计原则、城市设计控制策略、系统框架的建立,通过设计,可形成一个整体的、统一的视觉意象。通过城市设计,达到环境美化和高素质的社会文化。     

The effect of temperature inversions on ground-level nitrogen dioxide (NO2) and fine particulate matter (PM2.5) using temperature profiles from the Atmospheric Infrared Sounder (AIRS)

We investigate the effects of temperature inversions on the levels of nitrogen dioxide (NO₂) and fine particulate matter (PM2.5) in the atmosphere over the Hamilton Census Metropolitan Area and environs in Ontario, Canada, for the period 2003 to 2007. Vertical temperature profiles extracted from data acquired by the Atmospheric Infrared Sounder (AIRS) were used to determine the occurrences of daytime and nighttime temperature inversions over the region. NO₂ and PM2.5 data were obtained from three in situ air quality monitoring stations located in the study area. The results indicate increases of 49% and 54% in NO₂ and PM2.5 respectively, during nighttime inversion episodes. Daytime inversions resulted in an 11% increase in NO₂ but a 14% decrease in PM2.5. Decreases occurred predominantly in the summer. We discuss these results and possible explanations for the reduced PM2.5 concentrations on inversion days. Weekday and seasonal analysis, with associated meteorological parameters are also discussed.     

PM10 source apportionment in Milan (Italy) using time-resolved data

In this work Positive Matrix Factorization (PMF) was applied to 4-hour resolved PM10 data collected in Milan (Italy) during summer and winter 2006. PM10 characterisation included elements (Mg-Pb), main inorganic ions (NH₄⁺, NO₃⁻, SO₄²⁻), levoglucosan and its isomers (mannosan and galactosan), and organic and elemental carbon (OC and EC).PMF resolved seven factors that were assigned to construction works, re-suspended dust, secondary sulphate, traffic, industry, secondary nitrate, and wood burning. Multi Linear Regression was applied to obtain the PM10 source apportionment. The 4-hour temporal resolution allowed the estimation of the factor contributions during peculiar episodes, which would have not been detected with the traditional 24-hour sampling strategy.     

Inventory of aggregates in an expanding urban area

Faced with a potential shortage of aggregate, the Minnesota Department of Transportation funded a study to inventory the aggregates in four pilot areas of the state and compare it with the estimated requirements in these areas. Based on the results of the study, several methods were suggested to enhance the aggregate supply in these areas. The aggregate resources in the four pilot areas were determined by analyzing the geology of the deposits, both natural aggregate and crushed rock. In addition, reserves in permitted properties were determined using a questionnaire that was given to each quarry operator in these areas. Permitted properties were defined as those for which permits have been issued by the government unit having jurisdiction. Analysis of the questionnaire date was supplemented with interviews of county and state highway department personnel and local planning agencies. Aggregate demand in the four areas was determined from national and county models of demand. Computer-aided multiple regression models defined the relationships between aggregate demand and construction of public and private facilities, ratio of non-metal to metal construction products, and the price of aggregate. Four methods were suggested for enhancing the aggregate supply. These included the definition of quantity and quality of aggregate in the vicinity of urban areas, improvement in beneficiation techniques to maximize the utilization of mined material, development of end-use specifications to permit maximum use of lower grade reserves and of recycled pavements, and revision of land use regulations to prevent the loss of aggregate reserves to urban sprawl.     

Levels, chemical composition and sources of fine aerosol particles (PM1) in an area of the Mediterranean basin

Daily samples of fine aerosol particles (i.e., PM1, aerosol particles with an aerodynamic diameter less than 1.0 μm) were collected in Tito Scalo — Southern Italy — from April 2006 to March 2007. Measurements were performed by means of a low-volume gravimetric sampler, and each PM1 sample was analyzed by means of Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) or Atomic Absorption Spectrometry (GFAAS and FAAS) techniques in order to determine its content in fourteen trace elements (Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Ti and Zn). During the period examined, PM1 daily concentrations ranged between 0.3 µg m^− 3 and 55 µg m^− 3 with a mean value of 8 µg m^-3, a standard deviation of 7 µg m^− 3 and a median value of 6 µg m^− 3. As far as PM1 chemical composition is concerned, the mean values of the trace element concentrations decreased in the following order: Ca > Fe > Al > Na > K > Cr > Mg > Pb > Ni ≈ Ti ≈ Zn > Cd ≈ Cu > Mn. Principal Component Analysis (PCA) allowed the identification of three probable PM1 sources: industrial emissions, traffic and re-suspension of soil dust. Moreover, the results of a procedure applied to study the potential long-range transport contribution to PM1 chemical composition, showed that trace element concentrations do not seem to be affected by air mass origin and path. This was probably due to the strong impact of the local emission sources and the lack of the concentration measurements of some important elements and compounds that could better reveal the long-range transport influence on PM1 measurements at ground level.