Influence Of African Dust Research Articles

Characterization of organic aerosols at the Natura 2000 remote environment of Sanabria Lake (Spain): Evaluating the influence of African dust and regional biomass burning smoke

This work presents a thorough analysis of PM10 speciated organic composition at Sanabria Lake Natural Park, a rural remote area in NW-Spain, including diacids, hydroxy and poliacids, fatty acids, alkenoic acids, sugars, sugar alcohols, n-alkanes, PAHs, quinones, hopanes, tracers of biomass burning, and biogenic secondary organic aerosol (BSOA) from isoprene and α-pinene.PM10 ambient concentrations at Sanabria (mean value of 12.2 μg m−3) were within the typical range registered in regional-background air quality monitoring stations in Spain. However, the occurrence of African dust outbreaks and biomass burning events produced significant increases in the PM10 levels at this monitoring site (daily mean levels of 29.2 μg m−3 and 13.7 μg m−3, respectively).Major organic compounds were levoglucosan, sacharides and 2-methyltetrols, markers for biomass burning, soil dust and BSOA respectively.SOA contributed more than 53% of the total measured organics in summer Samples with high levels of SOA include most of the African dust events, suggesting that African dust might promote the formation of oxygenated species such as SOA derivatives in this area. This contribution decreased to a 14% in winter. Biomass burning tracers represented 37% of the analysed organic pollutants in winter, indicating that this is the main source of organic compounds in the colder seasons, mainly due to the influence of regional biomass burning events and the use of biomass as fuel in domestic heating. Hence, the fact that African dust outbreaks and biomass burning events are likely to become increasingly frequent in the context of climate change makes this type of analysis particularly relevant for assessing their impact on natural protected areas.

Elemental composition of airborne particulate matter from coastal South Florida area influenced by African dust events

• The elements Pb, Zn, V, Ni, Cd, As, Cr, and Cu presented the highest EFs. • As, Ni, Cd and Pb levels were below the maximum levels set by EU and USEPA. • REE were used to identify African dust contributions to the local APM. • The oil-fired Port Everglades Power Plant played an important role in the APM. • Road dust and waste incineration emissions were the second APM source of importance. Airborne particulate matter (APM) is a complex mixture of dust, dirt, soot and smoke containing both organic and inorganic components as well as biological particles. APM below 10 µm can enter the respiratory track and are known to cause adverse health effects. African dust storms are responsible for the transport of large amount of APM across the Atlantic Ocean during summer months. Anthropogenic activities are also responsible for APM pollution contribution in coastal areas and could have potential effects on sensitive ecosystems. The present study evaluates the elemental composition of APM collected from a coastal area in South Florida. In this study, a high-volume air sampler equipped with Versapor filters and located near the Port of Fort Lauderdale was employed for APM collection from 2005 to 2010. APM chemical composition was analyzed for multiple elements by ICP-MS. Seven of the eleven metals listed by the EPA as hazardous air pollutants (Mn, Cd, Cr, Ni, Pb, As, Co and Se) were detected in the samples. Iron and aluminum were the most abundant elements found in all samples, followed by V and Ni, which are usually associated with anthropogenic pollution coming from fossil fuel combustion. Specific sources of APM pollution were identified by principal component analysis and using the U.S. EPA UNMIX model for environmental data analyses. Rare earth elements were used to identify contributions of geological material to the APM and African dust influence during the summer months.

Impact of various air mass types on cloud condensation nuclei concentrations along coastal southeast Florida

Coastal southeast Florida experiences a wide range of aerosol conditions, including African dust, biomass burning (BB) aerosols, as well as sea salt and other locally-emitted aerosols. These aerosols are important sources of cloud condensation nuclei (CCN), which play an essential role in governing cloud radiative properties. As marine environments dominate the surface of Earth, CCN characteristics in coastal southeast Florida have broad implications for other regions with the added feature that this site is perturbed by both natural and anthropogenic emissions. This study investigates the influence of different air mass types on CCN concentrations at 0.2% (CCN0.2%) and 1.0% (CCN1.0%) supersaturation (SS) based on ground site measurements during selected months in 2013, 2017, and 2018. Average CCN0.2% and CCN1.0% concentrations were 373 ± 200 cm−3 and 584 ± 323 cm−3, respectively, for four selected days with minimal presence of African dust and BB (i.e., background days). CCN concentrations were not elevated on the four days with highest influence of African dust (289 ± 104 cm−3 [0.2% SS] and 591 ± 302 cm−3 [1.0% SS]), consistent with high dust mass concentrations comprised of coarse particles that are few in number. In contrast, CCN concentrations were substantially enhanced on the five days with the greatest impact from BB (1408 ± 976 cm−3 [0.2% SS] and 3337 ± 1252 cm−3 [1.0% SS]). Ratios of CCN0.2%:CCN1.0% were used to compare the hygroscopicity of the aerosols associated with African dust, BB, and background days. Average ratios were similar for days impacted by African dust and BB (0.54 ± 0.17 and 0.55 ± 0.17, respectively). A 29% higher average ratio was observed on background days (0.71 ± 0.14), owing in part to a strong presence of sea salt and reduced presence of more hydrophobic species such as those of a carbonaceous or mineral-dust nature. Finally, periods of heavy rainfall were shown to effectively decrease both CCN0.2% and CCN1.0% concentrations. However, the rate varied at which such concentrations increased after the rain. This work contributes knowledge on the nucleating ability of African dust and BB in a marine environment after varying periods of atmospheric transport (days to weeks). The results can be used to understand the hygroscopicity of these air mass types, predict how they may influence cloud properties, and provide a valuable model constraint when predicting CCN concentrations in comparable situations.

Synergistic effect of the occurrence of African dust outbreaks on atmospheric pollutant levels in the Madrid metropolitan area

The occurrence of African dust outbreaks over specific areas of the Mediterranean basin has been associated with increases in the PM10 concentration levels and also in the mortality rates. Different hypothesis have been proposed in the last years to explain the processes by which African dust storms generates negative health effect over urban areas in southern Europe but are still not clear. Some authors have suggested the existence of an interaction between air pollutants from local sources and the occurrence of African dust outbreaks, with a consequent increase in the risk of mortality due to exposure to these anthropogenic emissions. This study sought to identify such a synergistic effect in the Madrid metropolitan area. To this end, an assessment of the influence of African dust on air quality levels, the vertical structure of the atmosphere over Madrid and daily mortality was carried out. Our results indicated that African dust caused a reduction of the mixing layer height and the surface wind speed, by reducing the amount of solar radiation reaching the ground. These facts favored the accumulation of air pollutants emissions from local anthropogenic sources. Moreover, when the dust contribution to PM10 levels exceeded a threshold value (8 μg/m3), particulate matter mass (PM10, PM2.5) and number (ultra-fine particles) concentration as well as levels of gaseous air pollutants (CO, NO and NO2) registered at urban-background and urban-traffic monitoring sites, increased with statistical significance. In these conditions, it was found a statistically significant increase in risk of daily mortality in the PM10 exposure. Hence, ambient air in Madrid was more toxic during African dust events of increasing intensity due to this synergistic effect. Because it can be envisaged that the frequency, duration and intensity of dust storms will increase in the north of Africa due to climate change, it will be a priority to put forward and assess proposals to mitigate the adverse effects on health, focused on the reduction of air pollutant emissions from local sources, as well as proposals regarding the adaptation of the population in urban areas across the Mediterranean basin.

Determination and source apportionment of major and trace elements in atmospheric bulk deposition in a Caribbean rural area

Atmospheric deposition is considered to be the major pathway by which substances from the atmosphere enter to the terrestrial and aquatic ecosystems. This study constitutes the first exhaustive report on trace metal deposition in Cuba and is aimed to determine the monthly atmospheric flux of 47 major and trace elements in a Caribbean coastal site and investigate the main sources contributing to deposition.Bulk deposition (average of 46 018 μg m−2 day−1) and fluxes of studied elements showed a high variability and no seasonality with the dry and wet periods, results that we attributed to the fluctuations of the emissions from their main sources rather than to meteorological factors controlling the deposition processes. However, stronger correlations were found between typical crustal elements, which showed a marked seasonality with the presence of African cloud dust in the Caribbean. Lanthanoids element (Eu anomalies and LaN/LuN ratios) helped us to confirm the seasonal influence of African dust in the geochemical composition of bulk deposition in Cienfuegos. Most of the analysed elements were found in the range of variation of those reported in rural environments around the world but, the elements V, Ni, As and Sb reached higher levels, typically found in urban and industrial areas. The elements Sb, Pb, W, Sn, S, Cu, Mo, Nb and P were moderately enriched (10 < EF < 100) and Zn was highly enriched (EF > 100), indicating they were mainly derived from anthropogenic sources. The La/V ratios were found to be exclusively lower than 0.06 suggesting a strong influence of anthropogenic V emissions from industries with oil and/or petroleum-coke combustion processes. However, we found that V have a predominantly natural origin in the studied region which appear to be related with deposition processes dominated by large particles.Finally, Principal Component, Multilinear Regression and Cluster analyses led the identification of 5 main sources contributing to the bulk deposition: crustal matter (39.5%), marine aerosol (38.2%), combustions including the wastes incineration, wood and fossil fuel burning (6.7%), industries (8.7%) and road traffic (1.4%).

Saharan dust and forest fires in Southern Europe in the period 2001-2011: estimation and geographical distribution

Aim. In the context of the MED-PARTICLES project (EU LIFE+ ENV/IT/327) African dust outbreaks and wildfires over southern Europe were studied from 2001 to 2011, devoted to quantify short-term health effects of particulate matter over the Mediterranean region by distinguishing particle sizes, chemical components and sources. Methods. PM10 data from 19 regional and suburban background sites in the Mediterranean area were compiled. Daily influence of African dust and wildfires was assessed for each area, African dust contributions to PM10 were estimated and wildfire smoke plumes were classified according to their intensity. Results and conclusions. African dust outbreaks are more frequent in southern Mediterranean sites (30-37% vs. 20% days/year). A decreasing south to north gradient of African dust contribution to PM10 is patent. Higher annual dust contributions are encountered in the eastern Mediterranean with significantly higher contributions in autumn-spring and occurrence of various severe episodes throughout the year (over 100 µg m-3 dust in PM10). Clear summer prevalence is observed in the western part, with low occurrence of severe episodes. African dust emerges as the largest PM10 source in regional background southern sites of the Mediterranean (35-50% of PM10) with peak contributions up to 80% of the total PM10 mass in the eastern side. The multi-year study of African dust episodes and their contributions to PM10 displays a consistent decreasing trend in the period 2006/2007 to 2011 in the NW Mediterranean, almost parallel to that of NAO (North Atlantic Oscillation) index for the summer period, progressively more negative since 2006. As a consequence, a sharp change in the atmospheric circulation over the last 5 years has affected the number of African dust episodes and consequently the annual dust inputs to PM10 observed. Wildfires are more frequent in the eastern Basin, mainly concentrated in the warm season. A progressive decrease of wildfire events is observed in the western Mediterranean Basin.

African dust outbreaks over the Mediterranean Basin during 2001–2011: PM&amp;lt;sub&amp;gt;10&amp;lt;/sub&amp;gt; concentrations, phenomenology and trends, and its relation with synoptic and mesoscale meteorology

Abstract. The occurrence of African dust outbreaks over the whole Mediterranean Basin has been studied on an 11-yr period (2001–2011). In order to evaluate the impact of such mineral dust outbreaks on ambient concentrations of particulate matter, PM10 data from regional and suburban background sites across the Mediterranean area were compiled. After identifying the daily influence of African dust, a methodology for the estimation of the natural dust contributions on daily PM10 concentrations was applied. Our findings point out that African dust outbreaks are sensibly more frequent in southern sites across the Mediterranean, from 30 to 37% of the annual days, whereas they occur less than 20% of the annual days in northern sites. The central Mediterranean emerges as a transitional area, with slightly higher frequency of dust episodes in its lower extreme when compared to similar latitudinal positions in western and eastern sides of the Basin. A decreasing south to north gradient of African dust contribution to PM10, driven by the latitudinal position of the monitoring sites at least 25° E westwards across the Basin, is patent across the Mediterranean. As a result of this, an experimental equation for the estimation of annual African dust contributions based on the latitudinal position was obtained. From 25° E eastwards, higher annual dust contributions are encountered due to the elevated annual occurrence of severe episodes of dust but also because of inputs from Negev and Middle Eastern deserts. The slightly higher frequency of African dust episodes observed over southern sites in the central Mediterranean Basin is compensated by its moderately lower intensity. Concerning seasonality patterns and intensity characteristics, a clear summer prevalence is observed in the western part, with low occurrence of severe episodes (daily dust averages over 100 μg m−3 in PM10); no seasonal trend is detected in the central region, with moderate-intensity episodes; and significantly higher contributions are common in autumn-spring in the eastern side, with occurrence of various severe episodes throughout the year. Overall, African dust emerges as the largest PM10 source in regional background southern sites of the Mediterranean (35–50% of PM10), with seasonal peak contributions to PM10 up to 80% of the total mass. The multi-year study of African dust episodes and their contributions to PM10 concentrations reveals a consistent decreasing trend in the period 2006/2007 to 2011 in 4 of the 17 studied regions, all of them located in the NW of the Mediterranean. Such decrease is almost parallel to that of the NAO (North Atlantic Oscillation) index for the summer period, progressively more negative since 2006. Therefore, a sharp change in the atmospheric circulation over the last 5 yr (a similar negative NAO period occurred in the 1950 decade) have affected the number of African dust episodes and consequently the annual dust inputs to PM10 observed in the NW part of the Mediterranean. By investigating mean temperatures and geopotential height maps at 850 hPa it is evident a displacement of warm air masses accomplishing African dust towards the central Mediterranean in the 2007–2008 biennium, and towards the NW African coast and the Canary Islands in the 2009–2011 triennium.

Identification of the Influence of African Dust on PM10 Concentrations at the Athens Air Quality Monitoring Network during the Period 2001-2010

The objective of this work was to identify Sahara dust intrusions and quantify their contribution to annual and daily PM10 concentrations over the Athens Metropolitan Area (AMA) during the period 2001–2010. Additionally, extreme PM10 values attributed to large forest fires and volcanic emissions or the synergy of the above with African dust intrusions have been identified. It was found that the concentrations of PM10 during the period studied exceeded the European Union’s Air Quality Standard (EU AQS) value at most of the traffic urban (TU) stations. Most of the extreme values were attributed to dust events or large forest fires. The contribution from African dust to PM10 concentrations on days with events and exceedances of the EU AQS was approximately 50% at TU stations and 72% at the background suburban stations (BS). Most of the African dust events contributed about 5 μg/m3 to 34 μg/m3 to the daily PM10 concentrations, whereas the average contribution to annual PM10 concentrations was approximately 8.6 ± 1.8 μg/m3 i.e., 22.2 ± 7.5%. During the decade, no clear interannual relationship was observed between the African dust contribution and the frequency and intensity of events. The more frequent and severe episodes occurred during spring, while less frequent and less severe episodes occurred during summer. After the extraction of the African dust load the annual and daily AQS was exceeded in 2010 at only one TU station. The average annual contribution of African dust to the exceedances was approximately 36% at TU stations and 58% at BS stations.

Aerosols in the CALIOPE air quality modelling system: evaluation and analysis of PM levels, optical depths and chemical composition over Europe

Abstract. The CALIOPE air quality modelling system is developed and applied to Europe with high spatial resolution (12 km × 12 km). The modelled daily-to-seasonal aerosol variability over Europe in 2004 is evaluated and analysed. Aerosols are estimated from two models, CMAQv4.5 (AERO4) and BSC-DREAM8b. CMAQv4.5 calculates biogenic, anthropogenic and sea salt aerosol and BSC-DREAM8b provides the natural mineral dust contribution from North African deserts. For the evaluation, we use daily PM10, PM2.5 and aerosol components data from 55 stations of the EMEP/CREATE network and total, coarse and fine aerosol optical depth (AOD) data from 35 stations of the AERONET sun photometer network. Annual correlations between modelled and observed values for PM10 and PM2.5 are 0.55 and 0.47, respectively. Correlations for total, coarse and fine AOD are 0.51, 0.63, and 0.53, respectively. The higher correlations of the PM10 and the coarse mode AOD are largely due to the accurate representation of the African dust influence in the forecasting system. Overall PM and AOD levels are underestimated. The evaluation of the aerosol components highlights underestimations in the fine fraction of carbonaceous matter (EC and OC) and secondary inorganic aerosols (SIA; i.e. nitrate, sulphate and ammonium). The scores of the bulk parameters are significantly improved after applying a simple model bias correction based on the observed aerosol composition. The simulated PM10 and AOD present maximum values over the industrialized and populated Po Valley and Benelux regions. SIA are dominant in the fine fraction representing up to 80% of the aerosol budget in latitudes north of 40° N. In southern Europe, high PM10 and AOD are linked to the desert dust transport from the Sahara which contributes up to 40% of the aerosol budget. Maximum seasonal ground-level concentrations (PM10 &gt; 30 μg m−3) are found between spring and early autumn. We estimate that desert dust causes daily exceedances of the PM10 European air quality limit value (50 μg m−3) in large areas south of 45° N with more than 75 exceedances per year in the southernmost regions.

Influence of African dust on ocean–atmosphere variability in the tropical Atlantic

Tropical Atlantic sea surface temperatures and surface winds vary together in a pattern termed the Atlantic Meridional Mode. Simulations with an ocean general circulation model that is driven by a record of dust radiative forcing suggest that dust emissions over West Africa substantially influence the state of the tropical Atlantic Ocean on interannual to decadal scales.

Organic carbon, total nitrogen, and water-soluble ions in clouds from a tropical montane cloud forest in Puerto Rico

Chemical characterization to determine the organic and nitrogen fractions was performed on cloud water samples collected in a mountaintop site in Puerto Rico. Cloud water samples showed average concentrations of 1.09 mg L −1 of total organic carbon (TOC), of 0.85 mg L −1 for dissolved organic carbon (DOC) and of and 1.25 mg L −1 for total nitrogen (TN). Concentrations of organic nitrogen (ON) changed with the origin of the air mass. Changes in their concentrations were observed during periods under the influence of African dust (AD). The ON/TN ratios were 0.26 for the clean and 0.35 for the AD periods. Average concentrations of all these species were similar to those found in remote environments with no anthropogenic contribution. In the AD period, for cloud water the concentrations of TOC were 4 times higher and TN were 3 times higher than during periods of clean air masses associated with the trade winds. These results suggest that a significant fraction of TOC and TN in cloud and rainwater is associated to airborne particulate matter present in dust. Functional groups were identified using proton nuclear magnetic resonance ( 1H NMR) spectroscopy. This characterization led to the conclusion that water-soluble organic compounds in these samples are mainly aliphatic oxygenated compounds, with a small amount of aromatics. The ion chromatography results showed that the ionic species were predominantly of marine origin, for air masses with and without African dust influence, with cloud water concentrations of NO 3 − and NH 4 + much lower than from polluted areas in the US. An increase of such species as SO 4 2−, Cl −, Mg 2+, K + and Ca 2+ was seen when air masses originated from northwest Africa. The changes in the chemical composition and physical properties of clouds associated with these different types of aerosol particles could affect on cloud formation and processes.

African dust influence on ambient PM levels in South-Western Europe (Spain and Portugal): A quantitative approach to support implementation of Air Quality Directives

This manuscript proposes and validates a methodology for the quantification of the daily African PM load during dust outbreaks in southern Europe. The daily net dust load in PM10 attributable to an African episode can be obtained by subtracting the daily regional background (RB) level from the PM10 concentration value at a RB station. The daily RB level can be obtained by applying a monthly moving 30th percentile to the PM10 time series at a RB station after a prior extraction of the data coincident with African dust transport. For days with influence of African dust, the dust load is given by the difference between the daily PM10 values minus the daily PM10 RB levels. This method allows us to quantify the net African dust load without chemical speciation. The comparison between the estimated net load during African dust outbreaks (ADO) and the crustal load determined by chemical speciation of PM10 filters at three RB stations in Spain had resulted in a very good correlation (R2=0.60-0.83), being the equivalence (correlation lines' slopes ~ 1) highly significant in the three cases.

Ocean temperature forcing by aerosols across the Atlantic tropical cyclone development region

Recent work has shown a statistical climatological link between African dust outbreaks and North Atlantic tropical cyclone frequency and intensity. However, a definite causal link between year‐to‐year changes in African dust and Atlantic tropical cyclones has yet to be proven. Here we show that variability in Atlantic dust cover is linked to changes in tropical cyclone activity through the aerosols' surface radiative forcing, which has a net cooling effect on tropical Atlantic Ocean temperatures. In this manuscript we describe a new methodology for incorporating more than 25 years of satellite observations of aerosols into a simple model that estimates the aerosol direct effect and its impact on tropical eastern Atlantic Ocean temperatures. The output from our model suggests that African dust outbreaks play a nonnegligible role in the evolution of eastern Atlantic Ocean temperatures. Using the strong relationship between temperatures in the so‐called main development region and the seasonal power dissipation index (PDI), we estimate that about one third of the increase in PDI over the last 25 years can be attributed to decreases in dust loadings over the same period. Our results imply that efforts aimed at attributing causality to past variability of, or at predicting future changes in, North Atlantic tropical cyclone activity must consider the important radiative influence of African dust.

Spatial, Temporal, and Interspecies Patterns in Fine Particulate Matter in Texas

The Big Bend Regional Aerosol and Visibility Observational (BRAVO) field study was conducted from July to October 1999 and was followed by several years of modeling and data analyses to examine the causes of haze at Big Bend National Park TX (BBNP). During BRAVO, daily speciated fine (diameter <2.5 µm) particulate concentrations were measured at 37 sites throughout Texas. At the primary receptor site, K-Bar Ranch, there were many additional measurements including a “high-sensitivity” version of the 24-hr fine particulate elemental data. The spatial, temporal, and interspecies patterns in these data are examined here to qualitatively investigate source regions and source types influencing the fine particulate concentrations in Texas with an emphasis on sources of sulfates, the largest contributor to fine mass and light extinction. Peak values of particulate sulfur (S) varied spatially and seasonally. Maximum S was in Northeast Texas during the summer, whereas peak S at BBNP was in the fall. Sulfate acidity at BBNP also varied by month. Sources of Se were evident in Northeast Texas and from the Carbón I and II plants. High S episodes at BBNP during BRAVO had several different trace element characteristics. Carbon concentrations at BBNP during BRAVO were probably mostly urban‐related, with arrival from the Houston area likely. The Houston artificial tracer released during the second half of BRAVO was highly correlated with some carbon fractions. There was evidence of the influence of African dust at sites throughout Texas during the summer. Patterns in several trace elements were also examined. Vanadium was associated with air masses from Mexico. Lead concentrations in southern Texas have dropped dramatically over the past several years.

Wet and dry African dust episodes over eastern Spain

The impact of the African dust on levels of atmospheric suspended particulate matter (SPM) and on wet deposition was evaluated in eastern Iberia for the period 1996–2002. An effort was made to compile both the SPM and wet episodes. To this end, the time series of levels of TSP and PM10 in Levantine air quality monitoring stations were evaluated and complemented with the computation of back trajectories, satellite images, and meteorological analysis. Wet deposition frequency was obtained from weekly collected precipitation data at a rural background station in which the African chemical signature was identified (mainly pH and Ca2+ concentrations). A number of African dust episodes (112) were identified (16 episodes per year). In 93 out of the 112 (13 episodes per year) the African dust influence caused high SPM levels. In 49 out of 112 (7 episodes per year), wet deposition was detected, and the chemistry was influenced by dust. There is a clear seasonal trend with higher frequency of dust outbreaks in May‐August, with second modes in March and October. Wet events followed a different pattern, with a marked maximum in May. Except for one event, December was devoid of African air mass intrusions. On the basis of seasonal meteorological patterns affecting the Iberian Peninsula, an interpretation of the meteorological scenarios causing African dust transport over Iberia was carried out. Four scenarios were identified with a clear seasonal trend. The impact of the different dust outbreak scenarios on the levels of PM10 recorded at a rural site (Monagrega, Teruel, Spain) in the period 1996–2002 was also evaluated.

Influence of African dust on the levels of atmospheric particulates in the Canary Islands air quality network

Time series of levels of atmospheric particulate matter (TSP and PM10) were studied at 19 air quality monitoring stations in the islands of Tenerife and Gran Canaria (Canary Islands) during the period 1998–2000. After analysing seasonal variations, attention was focused on the detection of high TSP and PM10 events and on the identification of their natural or anthropogenic origins. Back-trajectory analysis and TOMS-NASA aerosol index as well as satellite imagery (SeaWIFS-NASA) were used to identify three types of African dust outbreaks differing in seasonal occurrence, source origin and impact on TSP/PM10 levels. Mean annual and daily TSP and PM10 levels were compared with the forthcoming limit values of the EU Air Quality Directive EC/30/1999, and the results showed that the annual and daily limit values established for 2010 would only be met at rural stations. PM levels at urban background, urban and industrial sites would exceed the 2010 objectives. Only the levels at the urban-background stations would meet the requirements for 2005 despite the fact that the trade winds result in lower levels of atmospheric pollutants in the Canary Islands than in continental environments. The results highlight the role of African dust contributions when implementing the limit values of the EU directive.