Sleep apnea and oxygen saturation in adults at 2640 m above sea level.

PURPOSE: To describe the SpO2 in wakefulness, sleep and during the apnea-hypopnea in adults living in Bogotá, located at 2640 m above sea level. METHODS: Descriptive observational study in adults referred for polysomnogram (PSG). A normal Apnea hypopnea index (AHI) was defined as ≤5 and obstructive sleep apnea (OSA) was classified as mild (AHI 5-15), moderate (AHI 15-30), and severe (AHI >30). T-test or ANOVA test for SpO2 differences between groups was used. RESULTS: 1799 patients, 33% women. 222 (12.8%) did not have OSA (normal IAH), 268 (14.9%) mild OSA, 315 (17.5%) moderate ,and 993 (55.2%) severe. In all cases a low SpO2 (SpO2<90%) was found. The SpO2 was lower when the AHI was higher, in wakefulness, in non-REM and in REM (p<0.001). For all grades of severity, SpO2 decreased significantly from wakefulness to non-REM sleep and to REM sleep (p<0.001). Patients with severe OSA had higher desaturation during wakefulness (85.2±6.6%), non-REM sleep (83.1±7.7%), REM sleep (78.8±10.2), and during events (75.1±9.1%). CONCLUSIONS: Patients with OSA at 2640 m have nocturnal desaturation lower than 88%, which decreases with higher severity of OSA. The clinical impact of sleep disorders at this point may be greater than at sea level and should be studied.

Tomographic and functional findings in severe COPD: comparison between the wood smoke-related and smoking-related disease.

OBJECTIVE: Wood smoke exposure is a risk factor for COPD. For a given degree of airway obstruction, the reduction in DLCO is smaller in individuals with wood smoke-related COPD than in those with smoking-related COPD, suggesting that there is less emphysema in the former. The objective of this study was to compare HRCT findings between women with wood smoke-related COPD and women with smoking-related COPD. METHODS: Twenty-two women with severe COPD (FEV1/FVC ratio < 70% and FEV1 < 50%) were divided into two groups: those with wood smoke-related COPD (n = 12) and those with smoking-related COPD (n = 10). The two groups were compared regarding emphysema scores and airway involvement (as determined by HRCT); and functional abnormalities-spirometry results, DLCO, alveolar volume (VA), the DLCO/VA ratio, lung volumes, and specific airway resistance (sRaw). RESULTS: There were no significant differences between the two groups in terms of FEV1, sRaw, or lung hyperinflation. Decreases in DLCO and in the DLCO/VA ratio were greater in the smoking-related COPD group subjects, who also had higher emphysema scores, in comparison with the wood smoke-related COPD group subjects. In the wood smoke-related COPD group, HRCT scans showed no significant emphysema, the main findings being peribronchial thickening, bronchial dilation, and subsegmental atelectasis. CONCLUSIONS: Female patients with severe wood smoke-related COPD do not appear to develop emphysema, although they do show severe airway involvement. The reduction in DLCO and VA, with a normal DLCO/VA ratio, is probably due to severe bronchial obstruction and incomplete mixing of inspired gas during the determination of single-breath DLCO.

Diferencias tomográficas y funcionales entre la EPOC severa relacionada con humo de leña y con cigarrillo: comparison between the wood smoke-related and smoking-related disease / Tomographic and functional findings in severe COPD

OBJETIVO: La exposición a humo de leña es factor de riesgo para EPOC. A diferencia de la EPOC por cigarrillo (EPOC-C), para un mismo nivel de obstrucción, en la EPOC por leña (EPOC-L), la DLCO está menos disminuida, sugiriendo menos enfisema. Por tanto, el objetivo de este estudio fue comparar los hallazgos en la TCAR en mujeres con EPOC-L y con EPOC- C. MÉTODOS: Veintidós mujeres con EPOC severa (VEF1/CVF < 70% y VEF1 < 50%) fueron divididas en dos grupos: las expuestas a leña (EPOC-L; n = 12) y las expuestas a cigarrillo (EPOC-C; n = 10). Se compararon los dos grupos con respecto al puntaje de enfisema y el compromiso de la vía aérea en la TCAR, las anormalidades funcionales en la espirometría, la DLCO, los volúmenes pulmonares y la resistencia específica de la vía aérea (sRaw). RESULTADOS: Los dos grupos tuvieron VEF1, sRaw e hiperinflación pulmonar similares. En el grupo EPOC-C, hubo mayor disminución de la DLCO y de la DLCO/VA y mayor puntaje de enfisema. En el grupo EPOC-L, no encontramos enfisema significativo en la TCAR. Los hallazgos principales fueron engrosamiento peribronquial, dilataciones bronquiales y atelectasias subsegmentarias. CONCLUSIONES: En pacientes con EPOC-L severa no hay enfisema en la TCAR. El hallazgo más importante es el compromiso severo de la vía aérea. La disminución de la DLCO y del VA con DLCO/VA normal es probablemente determinada por la obstrucción bronquial severa y la mezcla incompleta del gas inspirado en la maniobra de la respiración única de la prueba de difusión.

OBJECTIVE: Wood smoke exposure is a risk factor for COPD. For a given degree of airway obstruction, the reduction in DLCO is smaller in individuals with wood smoke-related COPD than in those with smoking-related COPD, suggesting that there is less emphysema in the former. The objective of this study was to compare HRCT findings between women with wood smoke-related COPD and women with smoking-related COPD. METHODS: Twenty-two women with severe COPD (FEV1/FVC ratio < 70% and FEV1 < 50%) were divided into two groups: those with wood smoke-related COPD (n = 12) and those with smoking-related COPD (n = 10). The two groups were compared regarding emphysema scores and airway involvement (as determined by HRCT); and functional abnormalities-spirometry results, DLCO, alveolar volume (VA), the DLCO/VA ratio, lung volumes, and specific airway resistance (sRaw). Results: There were no significant differences between the two groups in terms of FEV1, sRaw, or lung hyperinflation. Decreases in DLCO and in the DLCO/VA ratio were greater in the smoking-related COPD group subjects, who also had higher emphysema scores, in comparison with the wood smoke-related COPD group subjects. In the wood smoke-related COPD group, HRCT scans howed no significant emphysema, the main findings being peribronchial thickening, bronchial dilation, and subsegmental atelectasis. CONCLUSIONS: Female patients with severe wood smoke-related COPD do not appear to develop emphysema, although they do show severe airway involvement. The reduction in DLCO and VA, with a normal DLCO/VA ratio, is probably due to severe bronchial obstruction and incomplete mixing of inspired gas during the determination of single-breath DLCO.

Atmospheric stability of arsines and the determination of their oxidative products in atmospheric aerosols (PM10): evidence of the widespread phenomena of biovolatilization of arsenic.

Biovolatilisation of arsenic as their arsines in the form of AsH(3), and mono-, di and trimethylarsine has often been determined under laboratory conditions. Although environmental point sources such as landfill sites or hot springs have been characterised, only limited knowledge is available on how widespread the formation of volatile methylated arsenic compounds are in the environment. Here we studied the atmospheric stability of the different arsines and quantified their oxidation products in atmospheric particulate matter (PM(10)) in two locations in Argentina. The atmospheric half-life of the arsines range from 19 weeks for AsH(3) to 2 d for trimethylarsine (TMAs) at 20 degrees C in the dark, while during simulated daytime conditions the stability is reduced for all arsines and in particular for the methylated arsines by three orders of magnitude which suggests that TMAs can only be dispersed at night. At both locations the arsenic concentration was in all samples below 1 ng As m(-3), which is considered as rural background for arsenic. The oxidation products, i.e. methylarsonate (MA), dimethylarsinate (DMA) and trimethylarsine oxide (TMAO) were identified by using HPLC-ICP-MS/ES-MS in more than 90% of the 49 PM(10) samples taken from 8 sampling points at the two geographically different locations. TMAO was the predominate organoarsenicals in both locations (66 and 69%, respectively) while DMA was determined to be between 13 and 19% of all organoarsenicals at the two locations. The concentration of the organoarsenicals ranged from 4 to 60 pg As as TMAO m(-3), while the maximum concentration for DMA and MA were 16 and 6 pg As m(-3), respectively. No difference in terms of the concentration or distribution of the organoarsenicals in the PM(10) samples was identified as significant. Since the two locations were different in climate and industrial impact and sampled in different seasons, these data suggest that methylated arsenicals do occur as background chemicals in the environment. Due to the low atmospheric stability of the methylated arsines, it is suggested that biovolatilization of arsenic as methylated arsines is a widespread phenomenon. More studies however are necessary to identify the major sources and determine the flux of the volatilization process in order to determine whether or not the process has environmental significance.

Air pollution sources of PM(10) in Buenos Aires City.

To elucidate the sources of PM(10) air pollution from the experimental information collected in a local air quality monitoring campaign we have applied two methods, effective variance and genetic algorithms, in the solution of the chemical mass balance. The comparison of these two mathematical approaches show that the identification of the possible sources and the evaluation of its contributions are quite independent of them. The role of possible different sources for major and trace elements and the significance of standardizing available data is also addressed. We also present a simple method for identifying the number of candidate sources, a key element defining the dimension of the search space.

Fractionation of eleven elements by chemical bonding from airborne particulate matter collected in an industrial city in Argentina.

A four-step chemical sequential extraction procedure was used to evaluate the distribution of Al, As, Cr, Cu, Fe, Mn, Ni, Pb, Ti, V and Zn in airborne particulate matter collected on glass fibre filters using a high-volume sampler. Two sets of samples were collected in 2001 (winter and summer campaigns) in representative zones of an industrial city of Argentina. The leaching scheme was applied to PM-10 particles and consisted in extracting the elements in four fractions, namely soluble and exchangeable elements; carbonates, oxides and reducible elements; bound to organic matter and sulfidic metals; and residual elements. Metals and metalloids at microg g(-1) level were determined in each fraction by inductively coupled plasma optical emission spectrometry (ICP OES). Analyte concentration varied from 14 microg g(-1) (equivalent to 1.0 ng m(-3)) for As to 11.8 mg g(-1) (equivalent to 2,089 ng m(-3)) for Al. Seven elements, namely Al, Cr, Fe, Mn, Pb, Ti and Zn showed similar distributions in both seasons while As was distributed in a significantly different manner in each season. The results exhibited low As contents in the first and second fractions that could be associated with routine coal combustion and a high content in the third and fourth fractions of the summer samples that could be linked to the use of pesticides. Aluminium, As, Cu, Mn, Ni, Ti, V and Zn were found in different percentages in the more bioavailable aqueous fraction with As, Mn, V and Zn exhibiting solubilities greater than 1% while Cr and Pb being insoluble. The content of Al, Cr, Cu, Fe, Ni, Pb, and Zn in the residual fraction was, in average, higher than 50%. A comparative assessment of the use of the underlying information available from fractionation studies compared to that obtained from total element content was done for Fe and Mn. It showed that the results obtained using chemical sequential extraction procedures allowed further discrimination of the potential air pollution sources.

An analysis of secondary pollutants in Buenos Aires City.

Air pollutant concentrations from a monitoring campaign in Buenos Aires City, Argentina, are used to investigate the relationships between ambient levels of ozone (O3), nitric oxide (NO) and nitrogen dioxide (NO2) as a function of NO(x) (= NO + NO2). This campaign undertaken by the electricity sector was aimed at elucidating the apportionment of thermal power plants to air quality deterioration. Concentrations of carbon monoxide (CO) and sulphur dioxide (SO2) were also registered. Photo stationary state (PSS) of the NO, NO2, O3 and peroxy radicals species has been analysed. The 'oxidant' level concept has been introduced, OX (= O3 + NO2), which varies with the level of NO(x). It is shown that this level is made up of NO(x)-independent and NO(x)-dependent contributions. The former is a regional contribution that equates the background O3 level, whereas the latter is a local contribution that correlates with the level of primary pollution. Furthermore, the anticorrelation between NO2 and O3 levels, which is a characteristic of the atmospheric photo stationary cycle has been verified. The analysis of the concentration of the primary pollutants CO and NO strongly suggests that the vehicle traffic is the principal source of them. Levels of continuous measurements of SO2 for Buenos Aires City are reported in this work as a complement of previously published results.

Monitoring Pt and Rh in urban aerosols from Buenos Aires, Argentina.

Vehicular traffic is the main source of platinum group elements (PGEs) in highly populated urban areas like Buenos Aires where a traffic density of 1,500,000 vehicles day(-1) (corresponding to 7,500 vehicles km(-2)) is estimated. Since there is no information on the levels of PGEs in Buenos Aires, a pilot study was undertaken to ascertain the amount of two major PGEs, namely Pt and Rh, in the atmosphere of this city. To this end, 49 samples of PM-10 particulate matter were collected during 7 days in seven representative sampling sites located downtown Buenos Aires and spread over an area of about 30 km(2). The collection of particulate matter was performed on ash-free glass-fiber filters using high volume samplers with PM-10 sampling heads. Filters loaded with the particulate matter were subjected to microwave (MW)-assisted acid digestion using a combination of HNO(3), HF and HClO(4). The resulting solutions were evaporated and then diluted with 0.1 mol l(-1) HCl. Analyses were performed by sector field inductively coupled plasma-mass spectrometry (SF-ICP-MS) and special attention was paid to the control of mass interferences. Statistical analysis was performed on the experimental data obtained for the element concentrations taking also into account local meteorological data for the monitored period. The highest concentrations of Pt and Rh were detected at two sites (Hospital Alemán and Casa Rapallini) located in streets with traffic consisting mostly of passenger cars. The Pt content (in pg m(-3)) in airborne particulate matter was found to vary from 2.3 to 47.7, with a mean value of 12.9+/-7, and that of Rh from 0.3 to 16.8, with a mean value of 3.9+/-2.8. These concentrations are by far below the levels for which adverse health effects might be expected to occur, i.e., around 100 ng m(-3). On the other hand, monitoring of PGEs should be carried out in a systematic fashion to detect possible dramatic increases from today's levels.

Antimony: a traffic-related element in the atmosphere of Buenos Aires, Argentina.

Vehicular traffic is one of the main sources of antimony in highly populated urban areas like Buenos Aires where an overall traffic density of 1 500 000 vehicles per day (corresponding to 7500 vehicles km(-2)) is estimated. In this context, a study was undertaken to ascertain the levels of Sb and other traffic-related elements (TRE) in the atmosphere of this city. To this end, sixty-seven samples of PM-10 particulate matter were collected during eight days in nine representative sampling sites located downtown Buenos Aires and spread over an area of about 30 km2. The collection of particulate matter was performed on ash-free glass-fibre filters using high volume samplers with PM-10 sampling heads. A combination of aqua regia and perchloric acid was used for leaching metals from filters. The resulting solutions were evaporated and then diluted with 0.1 mol l(-1) HCl. Antimony was determined by inductively coupled plasma-quadrupole mass spectrometry (ICP-QMS) at ng g(-1) levels. Concentrations of Sb varied from 12.9 +/- 0.9 to 375 +/- 23 microg g(-1)(equivalent to 0.87 +/- 0.06 to 15.3 +/- 0.8 ng m(-3)). Statistical analysis was performed on the data set including the measured PM-10 mass and Sb concentrations for the monitored period. Correlations of Sb with other TRE namely, Cu and Mo were also assessed. The highest concentrations of Sb were detected at two sites (Hospital Alemán and Casa Rapallini) located in streets with traffic consisting mostly of passenger cars and showing a "stop-and-go" pattern in peak hours. Antimony levels in the Buenos Aires PM-10 are by far below the level of 0.5 mg m(-3)(for an 8 hour workday, 40 hour work week) set by the US Occupational Safety and Health Administration (OSHA) for occupational exposure. However, monitoring of Sb and other TRE should be carried out in a systematic fashion to detect the possibility of increases in from the present levels.

Elucidating a particulate matter deposition episode by combining scanning electron microscopy and X-ray fluorescence spectrometry.

Multielemental composition and morphology of particulate matter samples were examined to detect the presence of two potential responsible pollutant emitters at four sites impacted during a pollution episode in the City of Campana, Argentina. Coke and smoke black are the main constituents associated to the industrial plants that were considered, a priori, as responsible pollutant emitters. Wavelength dispersive X-ray fluorescence (WDXRF) was employed for the analysis of metals in samples coming from both, suspected sources and four sites. On the basis of multielemental composition profiles, a screening analysis was undertaken for exploring similarities among sources and sample sites adopting the average concentration profile of the crustal rock as soil surrogate. Particle morphology was studied by scanning electron microscopy (SEM) in source samples and in those environmental samples selected through the screening analysis. Two types of collected samples were analyzed: 1) those with composition profiles closer to the potential sources and 2) those closer to the cluster rock. This strategy was adequate to identify the responsible source of the contamination episode.

Metal fractionation of atmospheric aerosols via sequential chemical extraction: a review.

This review surveys schemes used to sequentially chemically fractionate metals and metalloids present in airborne particulate matter. It focuses mainly on sequential chemical fractionation schemes published over the last 15 years. These schemes have been classified into five main categories: (1) based on Tessier's procedure, (2) based on Chester's procedure, (3) based on Zatka's procedure, (4) based on BCR procedure, and (5) other procedures. The operational characteristics as well as the state of the art in metal fractionation of airborne particulate matter, fly ashes and workroom aerosols, in terms of applications, optimizations and innovations, are also described. Many references to other works in this area are provided.

A study of uniformity of elements deposition on glass fiber filters after collection of airborne particulate matter (PM-10), using a high-volume sampler.

A study was conducted to evaluate the homogeneity of the distribution of metals and metalloids deposited on glass fiber filters collected using a high-volume sampler equipped with a PM-10 sampling head. The airborne particulate matter (APM)-loaded glass fiber filters (with an active surface of about 500cm(2)) were weighed and then each filter was cut in five small discs of 6.5cm of diameter. Each disk was mineralized by acid-assisted microwave (MW) digestion using a mixture of nitric, perchloric and hydrofluoric acids. Analysis was performed by axial view inductively coupled plasma optical emission spectrometry (ICP OES) and the elements considered were: Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Sb, Ti and V. The validation of the procedure was performed by the analysis of the standard reference material NIST 1648, urban particulate matter. As a way of comparing the possible variability in trace elements distribution in a particular filter, the mean concentration for each element over the five positions (discs) was calculated and each element concentration was normalized to this mean value. Scatter plots of the normalized concentrations were examined for all elements and all sub-samples. We considered that an element was homogeneously distributed if its normalized concentrations in the 45 sub-samples were within +/-15% of the mean value ranging between 0.85 and 1.15. The study demonstrated that the 12 elements tested showed different distribution pattern. Aluminium, Cu and V showed the most homogeneous pattern while Cd and Ni exhibited the largest departures from the mean value in 13 out of the 45 discs analyzed. No preferential deposition was noticed in any sub-sample.

A combined analysis to identify airborne PM10 sources.

A two step procedure that combines an air dispersion model with a receptor model was used to identify the key sources that contribute to air levels of suspended particulate matter. The contribution to PM(10) concentrations measured at four monitoring sites in San Nicolas, Argentina, of the following sources, a thermal power plant, an integrated steel mill, motor vehicle exhaust fumes, and finally dust from paved and unpaved roads, have been analysed. Moreover, an air dispersion model was used to estimate the contribution of the thermal power plant, emissions of which have been described in depth by means of hourly fuel consumption and specific emission factors. The ratio "apportionment coefficient" was introduced to relate the contribution of this source to the measured 24 h PM(10) concentrations by analysing the frequency of occurrence of connecting winds between the power plant and each monitoring site. In San Nicolas 70% of the PM(10) sampled at three of the four monitoring sites could be attributed to the power plant in those scenarios where winds connected the facility's tall point sources with the sampling locations. The contribution to the measured PM(10) levels of the rest of the sources that are present in the analysed area was confirmed by way of receptor models. For this purpose, the multielemental composition of 41 samples was determined by Wavelength Dispersive X-ray Fluorescence analysis. In order to ascertain the underlying correlations between PM(10) samples and potential sources, Principal Component Analysis was performed on the standard matrix of composition profiles, which comprises the measured PM(10) samples being enlarged with the composition profiles of the potential contributing sources. The diagonalization of the covariance matrix was used as a screening procedure to differentiate the most likely contributing sources from those that were not significant.

Contaminantes secundarios en la Ciudad de Buenos Aires

Se estudia el comportamiento de los oxidantes atmosféricos (NO2 y O3) en función de diversas variables meteorológicas y la dependencia de sus concentraciones promedios con la hora del día para apreciar el ciclo foto-estacionario característico de las atmósferas urbanas. Se hace, además, un cálculo estimativo de la concentración de peroxiradicales sobre la base de la cinética del estado foto-estacionario. En el predio del Club de Amigos situado en el cruce de las avenidas Figueroa Alcorta y Sarmiento, Ciudad de Buenos Aires, Argentina, se midió en forma continua, en intervalos de tres minutos, durante aproximandamente dos meses, la concentración de los contaminantes gaseosos monóxido de carbono (CO); óxidos de nitrógeno (NOx), discriminados en monóxido de nitrógeno (NO) y dióxido de nitrógeno (NO2); ozono (O3) y dióxido de azufre (SO2). También se registraron valores horarios de material particulado en suspensión con diámetros aerodinámicos menores a 10 um (PM10)

Monitoring trace metals in urban aerosols from Buenos Aires city. Determination by plasma-based techniques.

A study was undertaken, within the framework of a 3 years national project, to assess the content of 13 elements in airborne particulate matter collected in representative zones of the metropolitan area of Buenos Aires. The sampling strategy followed consisted in collecting simultaneously 67 samples of PM10 particulate matter in 9 sampling sites covering an area of about 30 km2 during one week. The collection was performed on ash-free fibre-glass filters using high volume samplers. A combination of aqua regia and perchloric acid was used for leaching metals from filters. Key elements, namely Al, Ca, Cu, Fe, Mn, Mo, Ni, Pb, S, Sb, Sn, Zn and Zr, were determined by inductively coupled plasma-optical emission spectrometry (ICP-OES) and inductively coupled plasma-mass spectrometry (ICP-MS) at micro g g(-1) and ng g(-1) levels. Analyte concentration varied from 130 ng g(-1)(Mo) to over 30%(Ca). Multivariate statistical analysis was performed on the data set including the measured elemental compositions for the monitored period. The atmospheric concentration found for Pb confirms the decreasing levels of this element since the introduction of unleaded gasoline in 1995: 88 ng m(-3)(2001) < 220 ng m(-3)(1997) < 3900 ng m(-3)(1994). The average S concentration above 3 microg m(-3) is somehow unexpectedly high for Buenos Aires since the relatively low S content of liquid fuels and the massive usage of natural gas imply low emissions of this element from combustion activities. To the best of our knowledge, S concentrations are reported for the first time for this city.

The mean angular distance among objects and its relationships with Kohonen artificial neural networks.

This job refers to classification of multidimensional objects and Kohonen artificial neural networks. A new concept is introduced, called the mean angular distance among objects (MADO). Its value can be calculated as the cosine of the mean centered vectors between objects. It can be expressed in matrix form for any number of objects. The MADO allows us to interpret the final organization of the objects in a Kohonen map. Simulated examples demonstrate the relationship between MADO and Kohonen maps and show a way to take advantage of the information present in both of them. Finally, a real analytical chemistry case is analyzed as an application on a big data set of an air quality monitoring campaign. It is possible to discover in it a subgroup of objects with different characteristics than those of the general trend. This subgroup is linked to the existence of an unidentified SO(2) source that, a priori, has not been taken into account.

Identificación de fuentes de emisión por microscopía electrónica y difracción por rayos X

Estudio de identificación de fuentes de emisión de material particulado, tomando como base dos muestras patrón y analizando una muestra tomada en aire ambiente. Se analizaron mediante difracción de rayos X (DRX), microscopía electrónica de barrido (MEB), y espectrometría de energía dispersiva de rayos X (EDX)

Fractionation of elements by particle size of ashes ejected from Copahue Volcano, Argentina.

The volcano Copahue, Neuquén province, Argentina has shown infrequent explosive eruptions since the 18th century. Recently, eruptive activity and seismicity were registered in the period July-October, 2000. As a consequence, ash clouds were dispersed by winds and affected Caviahue village located at about 9 km east of the volcano. Samples of deposited particles from this area were collected during this episode for their chemical analysis to determine elements of concern with respect to the health of the local population and its environment. Different techniques were used to evaluate the distribution of elements in four particle size ranges from 36 to 300 microm. X-ray powder diffraction (XRD) was selected to detect major components namely, minerals, silicate glass, fragments of rocks and sulfurs. Major and minor elements (Al, Ca, Cl, Fe, K, Mg, Mn, Na, S, Si and Ti), were detected by energy dispersive X ray analysis (EDAX). Trace element (As, Cd, Cr, Cu, Hg, Ni, Pb, Sb, U, V and Zn) content was quantified by inductively coupled plasma-mass spectrometry (ICP-MS). Nuclear activation analysis (NAA) was employed for the determination of Ce, Co, Cs, Eu, Hf, La, Lu, Rb, Sc, Sm, Ta and Yb. An enrichment was observed in the smallest size fraction of volcanic ashes for four elements (As, Cd, Cu and Sb) of particular interest from the environmental and human health point of view.

Source extraction information from air quality data monitored in an Argentinean steel mill.

A statistical analysis of a series of ambient air concentrations of suspended particulate matter (SPM) and NO2 is presented. Measurements were taken at four sites that belong to an Argentinean steel mill and in another site located in its vicinity. The air pollutants were measured during a three-week exploratory sampling. The monitoring sites were selected on the basis of relevant characteristics of the emission sources and the corresponding climatological statistics of the last decade. Suspended particulate matter with aerodynamic diameter of less than 10 microm (PM10) and NO2 were continuously measured at only one site, while 1-hr samples of NO2 and 24-hr samples of total SPM and SO2 were collected at the other sites. The registered concentrations show that SPM was the pollutant of major concern. A first estimate about the nature of the contribution of the different sources of particles and NO2 present in the area was obtained through the statistical analysis of measured concentration data coupled with prevalent meteorological variables.