Spatiotemporal variations of tropospheric ozone in Spain (2008-2019).

This study aims to support the development of Spain's Ozone Mitigation Plan by evaluating the present-day spatial variation (2015-2019) and trends (2008-2019) for seven ground-level ozone (O3) metrics relevant for human/ecosystems exposure and regulatory purposes. Results indicate that the spatial variation of O3 depends on the part of the O3 distribution being analyzed. Metrics associated with moderate O3 concentrations depict an increasing O3 gradient between the northern and Mediterranean coasts due to climatic factors, while for metrics considering the upper end of the O3 distribution, this climatic gradient tends to attenuate in favor of hotspot regions pointing to relevant local/regional O3 formation. A classification of atmospheric regions in Spain is proposed based on their O3 pollution patterns, to identify priority areas (or O3 hotspots) where local/regional precursor abatement might significantly reduce O3 during pollution episodes. The trends assessment reveals a narrowing of the O3 distribution at the national level, with metrics influenced by lower concentrations tending to increase over time, and those reflecting the higher end of the O3 distribution tending to decrease. While most stations show no statistically significant variations, contrasting O3 trends are evident among the O3 hotspots. The Madrid area exhibits the majority of upward trends across all metrics, frequently with the highest increasing rates, implying increasing O3 associated with both chronic and episodic exposure. The Valencian Community area exhibits a mixed variation pattern, with moderate to high O3 metrics increasing and peak metrics decreasing, while O3 in areas downwind of Barcelona, the Guadalquivir Valley and Puertollano shows no variations. Sevilla is the only large Spanish city with generalized O3 decreasing trends. The different O3 trends among hotspots highlight the need for mitigation measures to be designed at a local/regional scale to be effective. This approach may offer valuable insights for other countries developing O3 mitigation plans.

Lessons from the COVID-19 air pollution decrease in Spain: Now what?

We offer an overview of the COVID-19 -driven air quality changes across 11 metropolises in Spain with the focus on lessons learned on how continuing abating pollution. Traffic flow decreased by up to 80% during the lockdown and remained relatively low during the full relaxation (June and July). After the lockdown a significant shift from public transport to private vehicles (+21% in Barcelona) persisted due to the pervasive fear that using public transport might increase the risk of SARS-CoV-2 infection, which need to be reverted as soon as possible. NO2 levels fell below 50% of the WHO annual air quality guidelines (WHOAQGs), but those of PM2.5 were reduced less than expected due to the lower contributions from traffic, increased contributions from agricultural and domestic biomass burning, or meteorological conditions favoring high secondary aerosol formation yields. Even during the lockdown, the annual PM2.5 WHOAQG was exceeded in cities within the NE and E regions with high NH3 emissions from farming and agriculture. Decreases in PM10 levels were greater than in PM2.5 due to reduced emissions from road dust, vehicle wear, and construction/demolition. Averaged O3 daily maximum 8-h (8hDM) experienced a generalized decrease in the rural receptor sites in the relaxation (June-July) with -20% reduced mobility. For urban areas O3 8hDM responses were heterogeneous, with increases or decreases depending on the period and location. Thus, after canceling out the effect of meteorology, 5 out of 11 cities experienced O3 decreases during the lockdown, while the remaining 6 either did not experience relevant reductions or increased. During the relaxation period and coinciding with the growing O3 season (June-July), most cities experienced decreases. However, the O3 WHOAQG was still exceeded during the lockdown and full relaxation periods in several cities. For secondary pollutants, such as O3 and PM2.5, further chemical and dispersion modeling along with source apportionment techniques to identify major precursor reduction targets are required to evaluate their abatement potential.

Infants' indoor and outdoor residential exposure to benzene and respiratory health in a Spanish cohort.

Benzene exposure represents a potential risk for children's health. Apart from being a known carcinogen for humans (group 1 according to IARC), there is scientific evidence suggesting a relationship between benzene exposure and respiratory problems in children. But results are still inconclusive and inconsistent. This study aims to assess the determinants of exposure to indoor and outdoor residential benzene levels and its relationship with respiratory health in infants. Participants were 1-year-old infants (N = 352) from the INMA cohort from Valencia (Spain). Residential benzene exposure levels were measured inside and outside dwellings by means of passive samplers in a 15-day campaign. Persistent cough, low respiratory tract infections and wheezing during the first year of life, and covariates (dwelling traits, lifestyle factors and sociodemographic data) were obtained from parental questionnaires. Multiple Tobit regression and logistic regression models were performed to assess factors associated to residential exposure levels and health associations, respectively. Indoor levels were higher than outdoor ones (1.46 and 0.77 µg/m3, respectively; p < 0.01). A considerable percentage of dwellings, 42% and 21% indoors and outdoors respectively, surpassed the WHO guideline of 1.7 µg/m3 derived from a lifetime risk of leukemia above 1/100 000. Monitoring season, maternal country of birth and parental tobacco consumption were associated with residential benzene exposure (indoor and outdoors). Additionally, indoor levels were associated with mother's age and type of heating, and outdoor levels were linked with zone of residence and distance from industrial areas. After adjustment for confounding factors, no significant associations were found between residential benzene exposure levels and respiratory health in infants. Hence, our study did not support the hypothesis for the benzene exposure effect on respiratory health in children. Even so, it highlights a public health concern related to the personal exposure levels, since a considerable number of children surpassed the abovementioned WHO guideline for benzene exposure.

Urban NH3 levels and sources in six major Spanish cities.

A detailed spatial and temporal assessment of urban NH3 levels and potential emission sources was made with passive samplers in six major Spanish cities (Barcelona, Madrid, A Coruña, Huelva, Santa Cruz de Tenerife and Valencia). Measurements were conducted during two different periods (winter-autumn and spring-summer) in each city. Barcelona showed the clearest spatial pattern, with the highest concentrations in the old city centre, an area characterised by a high population density and a dense urban architecture. The variability in NH3 concentrations did not follow a common seasonal pattern across the different cities. The relationship of urban NH3 with SO2 and NOX allowed concluding on the causes responsible for the variations in NH3 levels between measurement periods observed in Barcelona, Huelva and Madrid. However, the factors governing the variations in A Coruña, Valencia and Santa Cruz de Tenerife are still not fully understood. This study identified a broad variability in NH3 concentrations at the city-scale, and it confirms that NH3 sources in Spanish urban environments are vehicular traffic, biological sources (e.g. garbage containers), wastewater treatment plants, solid waste treatment plants and industry. The importance of NH3 monitoring in urban environments relies on its role as a precursor of secondary inorganic species and therefore PMX. Further research should be addressed in order to establish criteria to develop and implement mitigation strategies for cities, and to include urban NH3 sources in the emission inventories.

Variación espacial de la exposición a contaminación atmosférica en la ciudad de Valencia y su relación con un índice de privación / The spatial distribution of population exposure to outdoor air pollution in Valencia (Spain) and its association with a privation index

Objetivo: Evaluar la variación espacial de la exposición a dióxido de nitrógeno (NO2) en la ciudad de Valencia y su relación con la privación socioeconómica y la edad. Métodos: La población por sección censal (SC) procede del Instituto Nacional de Estadística. Los niveles de NO2 se midieron en 100 puntos del área de estudio, mediante captadores pasivos, en tres campañas entre 2002 y 2004. Se utilizó regresión por usos del suelo (LUR) para obtener el mapa de los niveles de NO2. Las predicciones del LUR se compararon con las proporcionadas por: a) el captador más cercano de la red de vigilancia, b) el captador pasivo más cercano, c) el conjunto de captadores en un entorno y d) kriging. Se asignaron niveles de contaminación para cada SC. Se analizó la relación entre los niveles de NO2, un índice de privación con cinco categorías y la edad (>65 años). Resultados: El modelo LUR resultó el método más preciso. Más del 99% de la población superó los niveles de seguridad propuestos por la Organización Mundial de la Salud. Se encontró una relación inversa entre los niveles de NO2 y el índice de privación (β = -2,01μg/m3 en el quintil de mayor privación respecto al de menor, IC95%: -3,07 a -0,95), y una relación directa con la edad (β = 0,12μg/m3 por incremento en unidad porcentual de población >65 años, IC95%: 0,08 a 0,16). Conclusiones: El método permitió obtener mapas de contaminación y describir la relación entre niveles de NO2 y características sociodemográficas (AU)

Objective: To evaluate spatial variation in exposure to nitrogen dioxide (NO2) air pollution in the city of Valencia, Spain, and its association with socioeconomic deprivation and age. Methods: Census tract population data were obtained from the National Statistics Institute of Spain. Outdoor NO2 was monitored in 100 sites in the study area, through the use of passive samplers, in three campaigns between 2002 and April 2004. Land use regression (LUR) was used to obtain a map of NO2 levels. The LUR predictions were compared with the NO2 level obtained by: a) the nearest sampler of the monitoring network, b) the nearest passive sampler, c) the mean distance-weighted levels of the samplers in the neighborhood, and d) the NO2 level obtained by using Kriging. For each census tract, the NO2 levels were obtained. The association of NO2 air pollution exposure with population age (>65 years) and the 5-category deprivation index was analyzed. Results: The LUR models showed less error than the other prediction methods. The safety levels proposed by the World Health Organization were exceeded in more than 99% of the population. An inverse relationship was found between NO2 levels and the deprivation index (β = -2.01μg/m3 in the most deprived quintile compared with lower deprivation, 95%CI: -3.07; -0.95) and a direct relationship was found with age (β = 0.12μg/m3 per unit increase in percentage of the population > 65 years, 95%CI: 0.08; 0.16). Conclusions: The method allowed pollution maps to be obtained and the association between NO2 levels and sociodemographic characteristics to be described (AU)

[The spatial distribution of population exposure to outdoor air pollution in Valencia (Spain) and its association with a privation index]. / Variación espacial de la exposición a contaminación atmosférica en la ciudad de Valencia y su relación con un índice de privación.

OBJECTIVE: To evaluate spatial variation in exposure to nitrogen dioxide (NO2) air pollution in the city of Valencia, Spain, and its association with socioeconomic deprivation and age. METHODS: Census tract population data were obtained from the National Statistics Institute of Spain. Outdoor NO2 was monitored in 100 sites in the study area, through the use of passive samplers, in three campaigns between 2002 and April 2004. Land use regression (LUR) was used to obtain a map of NO2 levels. The LUR predictions were compared with the NO2 level obtained by: a) the nearest sampler of the monitoring network, b) the nearest passive sampler, c) the mean distance-weighted levels of the samplers in the neighborhood, and d) the NO2 level obtained by using Kriging. For each census tract, the NO2 levels were obtained. The association of NO2 air pollution exposure with population age (≥65 years) and the 5-category deprivation index was analyzed. RESULTS: The LUR models showed less error than the other prediction methods. The safety levels proposed by the World Health Organization were exceeded in more than 99% of the population. An inverse relationship was found between NO2 levels and the deprivation index (ß = -2.01µg/m(3) in the most deprived quintile compared with lower deprivation, 95%CI: -3.07; -0.95) and a direct relationship was found with age (ß = 0.12µg/m(3) per unit increase in percentage of the population ≥ 65 years, 95%CI: 0.08; 0.16). CONCLUSIONS: The method allowed pollution maps to be obtained and the association between NO2 levels and sociodemographic characteristics to be described.

The use of experimental data and their uncertainty for assessing ozone photochemistry in the Eastern Iberian Peninsula.

Observation-based methods are useful tools to explore the sensitivity of ozone concentrations to precursor controls. With the aim of assessing the ozone precursor sensitivity in two locations: Paterna (suburban) and Villar del Arzobispo (rural) of the Turia river basin in the east of Spain, the photochemical indicator O(3)/NO(y) and the Extent-of-Reaction (EOR) parameter have been calculated from field measurements. In Paterna, the O(3)/NO(y) ratio varied from 0 to 13 with an average value of 5.1 (SD 3.2), whereas the averaged value for the EOR was 0.43 (SD 0.14). In Villar del Arzobispo, the O(3)/NO(y) ratio changed from 5 to 30 with a mean value of 13.6 (SD 4.7) and the EOR gave an averaged value of 0.72 (SD 0.11). The results show two different patterns of ozone production as a function of the location. The suburban area shows a VOC-sensitive regime whereas the rural one shows a transition regime close to NO(x)-sensitive conditions. No seasonal differences in these regimes are observed along the monitoring campaigns. Finally, an analysis of the influence of the measurement quality of NO(y), NO(x) and O(3) on the uncertainty of the O(3)/NO(y) ratio and the EOR was performed showing that the uncertainty of O(3)/NO(y) is not dependent on either its value or the individual values of O(3) and NO(y) but just on the quality of O(3) and NO(y) measurements. The maximum uncertainty is 26% as long as the combined uncertainties of O(3) and NO(y) remain below the 7.5%. The case of the EOR is different and its uncertainty depends on both the value of the EOR parameter and the individual concentration values of NO(y) and NO(x). The uncertainty of the EOR estimation can be very high (>200%) if the combined uncertainties of both NO(y) and NO(x) are high (>7.5%), or especially, if u(NO(y)) and u(NO(x)) differ considerably from each other (>3.5%).

Daily, seasonal and monthly variations in ozone levels recorded at the Turia river basin in Valencia (Eastern Spain).

INTRODUCTION: The Turia river basin, located in the east of the Iberian Peninsula, drains into the Mediterranean Sea near the city of Valencia (population, 814,208). The predominance of sea-breeze fluxes favours the inland transport of pollutants from the city up the basin where ozone concentrations exceeding the threshold for protection of human health are systematically recorded during the summer months. METHODS: This work analyses the variability in ozone levels by examining their spatial and temporal distribution in a Mediterranean river basin downwind from a city within the period 2005-2008. Orographic determinants and atmospheric fluxes induce strong variations in ozone measurements, even on relatively close locations. CONCLUSIONS: Results show a different behaviour of the monthly means and the daily cycles depending on the season of the year and the measuring environment, with summer/winter ratios ranging from 2.4 in cities to 1.6 inland, and mean values always higher in the interior of the basin. Daily cycles show significant summer/winter differences related to the predominant situations of anticyclonic stability in winter, which limit ventilation, and the predominant breeze circulations in summer. Results also show a "weekend effect" at urban and medium-distance stations. At the most inland station, the weekend/weekday behaviour differs according to the season of the year; weekend ozone levels are higher in spring, autumn and winter, and lower in summer, coinciding with the predominance of local wind cycles that favour air mass penetration inland from the coast.

Relevance of the economic crisis in chemical PM10 changes in a semi-arid industrial environment.

This paper shows the changes in PM(10) levels and chemical composition in a region in southeast Spain between two periods: September 2005-August 2006 and June 2008-May 2009. PM(10) levels in this arid region, with a great number of cement, ceramic and related industries, have decreased in the second period in concordance with the reduction of industrial production due to the economic crisis and the closure of a cement plant. Annual average levels of PM(10) decreased from 41 µg m(-3) in 2005 to 30 µg m(-3) in 2008 (27%) and to 23 µg m(-3) in 2009 (23%). The relative contribution of the different sources has not changed in the area in the latter period and the elements with mineral origin are the main components of the PM(10) composition. There is a reduction in the concentration of the components that have soil-related industries and crustal material resuspension as their main sources, mainly in the case of CO(3) (2-), Ca, Sr, Tl and Pb, but the seasonal patterns were the same in both periods. As a particular case, there is an uncoupling between the seasonal evolution of SO(2) and sulphates in the two study periods, which remarks the existence of a sulphate regional background that does not depend on SO(2) local emissions. The decrease of V, Ni and Tl levels reflects the reduction of the industrial activity during the crisis period, affecting mainly the ceramic sector characterised by a great decrease of Tl levels.

Outdoor, but not indoor, nitrogen dioxide exposure is associated with persistent cough during the first year of life.

BACKGROUND AND AIMS: Because their lungs and immune system are not completely developed, children are more susceptible to respiratory disease and more vulnerable to ambient pollution. We assessed the relation between prenatal and postnatal nitrogen dioxide (NO(2)) levels and the development of lower respiratory tract infections (LRTI), wheezing and persistent cough during the first year of life. METHODS: The study population consisted of 352 children from a birth cohort in Valencia, Spain. Prenatal exposure to NO(2), a marker of traffic related air pollution was measured at 93 sampling sites spread over the study area during four different sampling periods of 7 days each. It was modeled for each residential address through land use regression using the empirical measurements and data from geographic information systems. Postnatal exposure was measured once inside and outside each home using passive samplers for a period of 14 days. Outcomes studied were any episode of LRTI during the child's first year of life diagnosed by a doctor (bronchitis, bronchiolitis or pneumonia), wheezing (defined as whistling sounds coming from the chest), and persistent cough (more than three consecutive weeks). Outcomes and potential confounders were obtained from structured questionnaires. Multiple logistic regression was used to identify associations. RESULTS: The cumulative incidence (CI) at first year of life was 30.4% for LRTI (23.0% bronchiolitis, 11.9% bronchitis and 1.4% pneumonia), 26.1% for wheezing and 6.3% for persistent cough. The adjusted odds ratio (95% confidence interval) per 10µg/m(3) increment in postnatal outdoor NO(2) concentration was 1.40 (1.02-1.92) for persistent cough. We also found some pattern of association with LRTI, bronchiolitis, bronchitis, wheezing and persistent cough in different prenatal periods, although it was not statistically significant. CONCLUSIONS: Our results indicate that exposure to outdoor, but not indoor, NO(2) during the first year of life increases the risk of persistent cough.

Influence of local and regional Mediterranean meteorology on SO2 ground-level concentrations in SE Spain.

This work presents the results of a 4-year study on sulfur dioxide (SO(2)) ground-level concentrations in an area of southeastern Spain, the L'Alacantí region, where the cement industry is important and coke use extends to other industries as well. The main source of SO(2) emissions in the area was found to be a the Lepold cement plant (one of the two cement plants in the area). The high levels of SO(2) probably extend back to 1920 when this plant began operations. Both local and Mediterranean-scale meteorological processes influence the SO(2) ground-level concentration and together explain the dispersion dynamics of this pollutant. The location and topography of the study zone result in NW Atlantic advections and E-SE sea breezes being the dominant atmospheric circulation patterns in the area. Under stable meteorological conditions, minor local circulations are also relevant to the SO(2) concentration levels. The high frequency of local circulations determines a concentration pattern that changes during the day, with impacts occurring preferentially in a W-NW direction from the source at midday (sea breeze and strong thermal mixture), and in a SE direction at night. This causes the SO(2) concentrations to present well-defined diurnal cycles with well-differentiated shapes depending on the location of the sampling station relative to the source. The dependence of SO(2) 10 min levels on the wind origin and speed throughout the day has been evaluated by studying statistical parameters including P95, P50 and arithmetic mean. Exceedances occur under specific dispersion conditions at distances less than 1 km from the source. However, the source is traceable at larger distances and the levels are higher than typical urban ones. P95 was used as an estimator of the occurrence of larger levels or impacts. Leeward of NW winds and the source, at night and in early morning, P95 levels are comprised between 30 and 55 µg m(-3). In contrast, with SE winds and at midday, P95 levels stay at 17 µg m(-3). The same P95 was obtained for winds lower than 5 m s(-1), which represent 89% of the winds in the area. However, stronger winds can have P95 levels above 125 µg m(-3).

Source apportionment of PM(10) and PM(2.5) at multiple sites in the strait of Gibraltar by PMF: impact of shipping emissions.

BACKGROUND: The impact of shipping emissions on urban agglomerations close to major ports and vessel routes is probably one of the lesser understood aspects of anthropogenic air pollution. Little research has been done providing a satisfactory comprehension of the relationship between primary pollutant emissions, secondary aerosols formation and resulting air quality. MATERIALS AND METHODS: In this study, multi-year (2003-2007) ambient speciated PM(10) and PM(2.5) data collected at four strategic sampling locations around the Bay of Algeciras (southern Spain), and positive matrix factorisation model were used to identify major PM sources with particular attention paid to the quantification of total shipping emissions. The impact of the emissions from both the harbour of Algeciras and vessel traffic at the Western entrance of Mediterranean Sea (Strait of Gibraltar) were quantified. Ambient levels of V, Ni, La and Ce were used as markers to estimate PM emitted by shipping. RESULTS AND DISCUSSION: Shipping emissions were characterised by La/Ce ratios between 0.6 and 0.8 and V/Ni ratios around 3 for both PM(10) and PM(2.5). In contrast, elevated La/Ce values (1-5) are attributable to emissions from refinery zeolitic fluid catalytic converter plant, and low average V/Ni values (around 1) result mainly from contamination from stainless steel plant emissions. The direct contribution from shipping in the Bay of Algeciras was estimated at 1.4-2.6 µg PM(10)/m(3) (3-7%) and 1.2-2.3 µg PM(2.5)/m(3) (5-10%). The total contribution from shipping (primary emissions + secondary sulphate aerosol formation) reached 4.7 µg PM(10)/m(3) (13%) and 4.1 µg PM(2.5)/m(3) (17%).

Indoor and outdoor air concentrations of BTEX and determinants in a cohort of one-year old children in Valencia, Spain.

BTEX is the commonly used term for a group of toxic compounds (benzene, toluene, ethyl benzene, ortho-xylene and meta- and para-xylene), some of which, most notably benzene, are known carcinogens. The aim of this study is to measure the BTEX levels both inside and outside the homes of 352 one-year old children from the Valencia cohort of the INMA study (Spain) and to analyze the determinants of these levels. Passive samplers were used to measure BTEX levels during a 15day period and a questionnaire was administered to gather information on potentially associated factors (sociodemographics, residential conditions, and lifestyle). The average concentrations of benzene, toluene, ethyl benzene, ortho-xylene, and meta- and para-xylene were 0.9, 3.6, 0.6, 0.6, and 1.0µg/m(3), respectively. On average, the indoor levels of all the compounds were approximately 2.5 times higher than those observed outdoors. Factors associated with higher BTEX concentrations inside the home were being the child of a mother of non-Spanish origin, living in a house that had been painted within the last year, living in an apartment, and not having air conditioning. Higher outdoor concentrations of BTEX depend on the residence being situated in a more urban zone, being located within the city limits, having living in a building with more than one story, residing in an area with a greater frequency of traffic, and the season of the year in which the sample was taken. The data thus obtained provide helpful information not only for implementing measures to reduce exposure to these pollutants, but also for evaluating the relation between such exposure and possible health risks for the children in the cohort.

Analysis of tropospheric ozone concentration on a Western Mediterranean site: Castellon (Spain).

Ozone dynamics in our study area (Castellon, Spain) is both strongly bound to the mesoscale circulations that develop under the effect of high insolation (especially in summer) and conditioned by the morphological characteristics of the Western Mediterranean Basin. In this work we present a preliminary analysis of ozone time series on five locations in Castellon for the period 1997-2003. We study their temporal and spatial variations at different scales: daily, weekly, seasonally and interannually. Because both the O3 concentration and its temporal variation depend on the topographic location of the observing station, they can show large differences within tens of kilometer. We also contrast the variation in the ozone concentration with the variations found for meteorological variables such as radiation, temperature, relative humidity and recirculation of the air mass. The link between elevated ozone concentrations and high values of the recirculation factor (r=0.7-0.9) shown the importance of recirculating flows on the local air pollution episodes.

Geochemistry and origin of PM10 in the Huelva region, Southwestern Spain.

The results of chemical analysis of PM(10) atmospheric dust samples collected between July 2001 and June 2002 in rural and urban background monitoring stations in Huelva (South-western Spain) are reported. In order to identify the sources and quantify their contribution to PM(10), principal component analysis and receptor modelling techniques were performed using independent variables of the complete series of concentrations of PM(10) contents. The Ria of Huelva is considered to be one of the high industrial estates in Spain, where several metallurgical, petrochemical and fertilizer industrial estates are located, surrounded by areas of a high ecological interest such as Doñana National Park. Annual means of 29-33 and 37 micro g PM(10)m(-3) were obtained for the study period in rural and urban monitoring stations, respectively. These values are below the mean annual limit value for 2005 and onwards from the Directive 1999/30/EC [EU, 1999. 1999/30/CE Council Directive relating to limit values for sulphur dioxide, nitrogen dioxide and oxide of nitrogen, particulate matter and lead in ambient air. The Council of the European Union]. High PM(10) episodes in rural and urban areas occurred during African dust events. Episodically, the emissions of plumes from industrial estates reach rural areas causing peak episodes of PO(4)(3-) Cu, Ti Pb and As. Anthropogenic particles arising from metallurgical emissions (pyrite, chalcopyrite and sphalerite) were observed in the rural sites. The annual mean As concentrations measured in PM(10) in the city of Huelva and surrounding rural areas (144 and 84-51mg Askg(-1) in PM(10), respectively) are several times high the concentrations obtained in other Spanish monitoring stations (7-57mg Askg(-1)). The source apportionment analyses allowed the quantification of the contribution to PM(10) of an industrial mixed source in the rural background.

Identification and chemical characterization of industrial particulate matter sources in southwest Spain.

A detailed physical and chemical characterization of coarse particulate matter (PM10) and fine particulate matter (PM2.5) in the city of Huelva (in Southwestern Spain) was carried out during 2001 and 2002. To identify the major emission sources with a significant influence on PM10 and PM2.5, a methodology was developed based on the combination of: (1) real-time measurements of levels of PM10, PM2.5, and very fine particulate matter (PM1); (2) chemical characterization and source apportionment analysis of PM10 and PM2.5; and (3) intensive measurements in field campaigns to characterize the emission plumes of several point sources. Annual means of 37, 19, and 16 microg/m3 were obtained for the study period for PM10, PM2.5, and PM1, respectively. High PM episodes, characterized by a very fine grain size distribution, are frequently detected in Huelva mainly in the winter as the result of the impact of the industrial emission plumes on the city. Chemical analysis showed that PM at Huelva is characterized by high PO4(3-) and As levels, as expected from the industrial activities. Source apportionment analyses identified a crustal source (36% of PM10 and 31% of PM2.5); a traffic-related source (33% of PM10 and 29% of PM2.5), and a marine aerosol contribution (only in PM10, 4%). In addition, two industrial emission sources were identified in PM10 and PM2.5: (1) a petrochemical source, 13% in PM10 and 8% in PM2.5; and (2) a mixed metallurgical-phosphate source, which accounts for 11-12% of PM10 and PM2.5. In PM2.5 a secondary source has been also identified, which contributed to 17% of the mass. A complete characterization of industrial emission plumes during their impact on the ground allowed for the identification of tracer species for specific point sources, such as petrochemical, metallurgic, and fertilizer and phosphate production industries.

Comparative PM10-PM2.5 source contribution study at rural, urban and industrial sites during PM episodes in Eastern Spain.

In this study a set of 340 PM10 and PM2.5 samples collected throughout 16 months at rural, an urban kerbside and an industrial background site (affected by the emissions from the ceramic manufacture and other activities) were interpreted. On the regional scale, the main PM10 sources were mineral dust (mainly Al2O3, Fe, Ti, Sr, CaCO3, Mg, Mn and K), emissions derived from power generation (SO4=, V, Zn and Ni), vehicle exhausts (organic and elemental carbon, NO3- and trace elements) and marine aerosol (Na, Cl and Mg). The latter was not identified in PM2.5. At the industrial site, additional PM10 sources were identified (tile covering in the ceramic production, petrochemical emissions and bio-mass burning from a large orange tree cultivation area). The contribution of each PM source to PM10 and PM2.5 levels experiences significant variations depending on the type of PM episode (Local-urban mainly in autumn-winter, regional mainly in summer, African or Atlantic episode), which are discussed in this study. The results show that it would be very difficult to meet the EU limit values for PM10 established for 2010. The annual mean PM levels are 22.0 microg PM10/m3 at the rural and 49.5 microg PM10/m3 and 33.9 microg PM2.5/m3 at the urban site. The natural contribution in this region, estimated at 6 microg/m3 of natural mineral dust (resulting from the African events and natural resuspension) and 2 microg/m3 of marine aerosol, accounts for 40% of the 2010 EU annual limit value (20 microg PM10/m3). Mineral dust concentrations at the urban and industrial sites are higher than those at the rural site because of the urban road dust and the ceramic-production contributions, respectively. At the urban site, the vehicle exhaust contribution (17 microg/m3) alone is very close to the 2010 EU PM10 limit value. At the rural site, the African dust is the main contributor to PM10 levels during the highest daily mean PM10 events (100th-97th percentile range). At the urban site, the vehicle exhaust product is the main contributor to PM10 and PM2.5 levels during the highest daily mean PM events (100th-85th percentile range). Mineral dust concentrations during African dust events accounts for 20-30 microg/m3 in PM10 and 10-15 microg/m3 in PM2.5. During non-African dust events, mineral dust derived from anthropogenic activities (e.g. urban road dust) is also a significant contributor to PM10, but not to PM2.5.

Events affecting levels and seasonal evolution of airborne particulate matter concentrations in the Western Mediterranean.

Time series (1996-2000) of levels of PM (PM10 and TSP) and gaseous pollutants recorded in air quality monitoring networks from Northeastern Spain were interpreted using meteorological data and satellite observations of African dust plumes. The main objective of this study was to identify the processes affecting time variations of PM levels on a day-to-day and seasonal basis. From March to October PM levels at rural, urban, and industrial sites vary as a function of the concatenation of Atlantic air mass advections (Atlantic episodes with low PM levels) and regional circulations (regional events with high PM levels, very often associated with high ozone levels), which favor the aging of air masses in the Western Mediterranean basin. During these regional episodes, PM is transported from urban/industrial to rural sites by meso-scale circulations. From November to February low PM levels are recorded at rural sites, and variations in PM levels at urban/industrial sites are governed by the successive occurrence of Atlantic episodes and local urban/industrial pollution events. The African dust outbreaks take place throughout the year and may induce PM levels to increase simultaneously in large areas of the Iberian peninsula. The difference between PM concentrations measured at urban and rural sites experiences a seasonal trend similar to that of levels of NO(x) and CO, which is characterized by a winter maximum due to the higher frequency of intensive local urban pollution events. However, maximum PM levels are recorded in summer at rural sites owing to the frequent occurrence of regional episodes. Furthermore, in three years of the study period (1997, 1998, and 2000), a second-order PM maximum was also recorded at rural sites in March owing to intensive African dust outbreaks.

Atmospheric dynamics and ozone cycles related to nitrogen deposition in the western Mediterranean.

Recent results from EU-sponsored projects have shed new light on the workings of the atmosphere in the Mediterranean Basin, where a large airmass becomes trapped and nearly stagnant over the sea during the summer. This work reviews the developments which have led to our present understanding of air pollution dynamics and associated meteorological processes in this region. In summer, the sea breezes combine with upslope winds to create recirculations along the coasts and within the western Mediterranean basin, with residence times in the order of days. Under strong insolation these recirculations become "large natural photo-chemical reactors" where most of the NOx emissions and other precursors are transformed into oxidants, acidic compounds, aerosols and ozone, which can exceed European Union directives for several months of the year. The objective of this paper is to evaluate available experimental evidence and complementary modelling results to help in the interpretation of observed ozone cycles and to anticipate possible scenarios for anthropogenic nitrogen deposition in the region.