Coarse particles from Saharan dust and daily mortality

Natural sources of atmospheric aerosols influencing air quality across Europe

Atmospheric aerosols are emitted by natural and anthropogenic sources. Contributions from natural sources to ambient aerosols vary widely with time (inter-annual and seasonal variability) and as a function of the distance to source regions. This work aims to identify the main natural sources of atmospheric aerosols affecting air quality across Europe. The origin, frequency, magnitude, and spatial and temporal variability of natural events were assessed for the years 2008 and 2009. The main natural sources of atmospheric aerosols identified were African dust, sea spray and wildfires. Primary biological particles were not included in the present work. Volcanic eruptions did not affect air quality significantly in Europe during the study period. The impact of natural episodes on air quality was significant in Southern and Western Europe (Cyprus, Spain, France, UK, Greece, Malta, Italy and Portugal), where they contributed to surpass the PM10 daily and annual limit values. In Central and Northern Europe (Germany, Austria and Latvia) the impact of these events was lower, as it resulted in the exceedance of PM daily but not annual limit values. Contributions from natural sources to mean annual PM10 levels in 2008 and 2009 ranged between 1 and 2 μg/m(3) in Italy, France and Portugal, between 1 and 4 μg/m(3) in Spain (10 μg/m(3) when including the Canary Islands), 5 μg/m(3) in UK, between 3 and 8 μg/m(3) in Greece, and reached up to 13 μg/m(3) in Cyprus. The evaluation of the number of monitoring stations per country reporting natural exceedances of the daily limit value (DLV) is suggested as a potential tool for air quality monitoring networks to detect outliers in the assessment of natural contributions. It is strongly suggested that a reference methodology for the identification and quantification of African dust contributions should be adopted across Europe.

Desert dust and human health disorders

Dust storms may originate in many of the world's drylands and have an effect not only on human health in the drylands themselves but also in downwind environments, including some major urban centres, such as Phoenix, Kano, Athens, Madrid, Dubai, Jedda, Tehran, Jaipur, Beijing, Shanghai, Seoul, Taipei, Tokyo, Sydney, Brisbane and Melbourne. In some parts of the world dust storms occur frequently throughout the year. They can transport particulate material, pollutants, and potential allergens over thousands of km from source. The main sources include the Sahara, central and eastern Asia, the Middle East, and parts of the western USA. In some parts of the world, though not all, the frequency of dust storms is changing in response to land use and climatic changes, and in such locations the health implications may become more severe. Data on the PM10 and P2.5 loadings of dust events are discussed, as are various pollutants (heavy metals, pesticides, etc.) and biological components (spores, fungi, bacteria, etc.). Particulate loadings can far exceed healthy levels. Among the human health effects of dust storms are respiratory disorders (including asthma, tracheitis, pneumonia, allergic rhinitis and silicosis) cardiovascular disorders (including stroke), conjunctivitis, skin irritations, meningococcal meningitis, valley fever, diseases associated with toxic algal blooms and mortality and injuries related to transport accidents.

Short-term effect of dust storms on the risk of mortality due to respiratory, cardiovascular and all-causes in Kuwait

This study aimed to investigate the impact of dust storms on short-term mortality in Kuwait. We analyzed respiratory and cardiovascular mortality as well as all-cause mortality in relation to dust storm events over a 5-year study period, using data obtained through a population-based retrospective ecological time series study. Dust storm days were identified when the national daily average of PM10 exceeded 200 μg/m(3). Generalized additive models with Poisson link were used to estimate the relative risk (RR) of age-stratified daily mortality associated with dust events, after adjusting for potential confounders including weather variables and long-term trends. There was no significant association between dust storm events and same-day respiratory mortality (RR = 0.96; 95%CI 0.88-1.04), cardiovascular mortality (RR = 0.98; 95%CI 0.96-1.012) or all-cause mortality (RR = 0.99; 95%CI 0.97-1.00). Overall our findings suggest that local dust, that most likely originates from crustal materials, has little impact on short-term respiratory, cardiovascular or all-cause mortality.

Impact of Saharan dust particles on hospital admissions in Madrid (Spain)

Saharan dust intrusions make a major contribution to levels of particulate matter (PM) present in the atmosphere of large cities. We analysed the impact of different PM fractions during periods with and without Saharan dust intrusions, using time-series analysis with Poisson regression models, based on: concentrations of coarse PM (PM10 and PM10-2.5) and fine PM (PM2.5); and daily all-, circulatory- and respiratory-cause hospital admissions. While periods without Saharan dust intrusions were marked by a statistically significant association between daily mean PM2.5 concentrations and all- and circulatory-cause hospital admissions, periods with such intrusions saw a significant increase in respiratory-cause admissions associated with fractions corresponding to PM10 and PM10-2.5.

Contribution of dust storms to PM10 levels in an urban arid environment

Quantitative information on the contribution of dust storms to atmospheric PM10 (particulate matter with an aerodynamic diameter < or = 10 microm) levels is still lacking, especially in urban environments with close proximity to dust sources. The main objective of this study was to quantify the contribution of dust storms to PM10 concentrations in a desert urban center, the city of Beer-Sheva, Negev, Israel, during the period of 2001-2012. Toward this end, a background value based on the "dust-free" season was used as a threshold value to identify potentially "dust days." Subsequently, the net contribution of dust storms to PM10 was assessed. During the study period, daily PM10 concentrations ranged from 6 to over 2000 microg/m3. In each year, over 10% of the daily concentrations exceeded the calculated threshold (BVt) of 71 microg/m3. An average daily net contribution of dust to PM10 of 122 microg/m3 was calculated for the entire study period based on this background value. Furthermore, a dust storm intensity parameter (Ai) was used to analyze several storms with very high PM10 contributions (hourly averages of 1000-5197 microg/m3). This analysis revealed that the strongest storms occurred mainly in the last 3 yr of the study. Finally, these findings indicate that this arid urban environment experiences high PM10 levels whose origin lies in both local and regional dust events.

IMPLICATIONS

The findings indicate that over time, the urban arid environment experiences high PM10 levels whose origin lies in local and regional dust events. It was noticed that the strongest storms have occurred mainly in the last 3 yr. It is believed that environmental changes such as global warming and desertification may lead to an increased air pollution and risk exposure to human health.

Errors in coarse particulate matter mass concentrations and spatiotemporal characteristics when using subtraction estimation methods

In studies of coarse particulate matter (PM10-2.5), mass concentrations are often estimated through the subtraction of PM2.5 from collocated PM10 tapered element oscillating microbalance (TEOM) measurements. Though all field instruments have yet to be updated, the Filter Dynamic Measurement System (FDMS) was introduced to account for the loss of semivolatile material from heated TEOM filters. To assess errors in PM10-2.5 estimation when using the possible combinations of PM10 and PM2.5 TEOM units with and without FDMS, data from three monitoring sites of the Colorado Coarse Rural-Urban Sources and Health (CCRUSH) study were used to simulate four possible subtraction methods for estimating PM10-2.5 mass concentrations. Assuming all mass is accounted for using collocated TEOMs with FDMS, the three other subtraction methods were assessed for biases in absolute mass concentration, temporal variability, spatial correlation, and homogeneity. Results show collocated units without FDMS closely estimate actual PM10-2.5 mass and spatial characteristics due to the very low semivolatile PM10-2.5 concentrations in Colorado. Estimation using either a PM2.5 or PM10 monitor without FDMS introduced absolute biases of 2.4 microg/m3 (25%) to -2.3 microg/m3 (-24%), respectively. Such errors are directly related to the unmeasured semivolatile mass and alter measures of spatiotemporal variability and homogeneity, all of which have implications for the regulatory and epidemiology communities concerned about PM10-2.5. Two monitoring sites operated by the state of Colorado were considered for inclusion in the CCRUSH acute health effects study, but concentrations were biased due to sampling with an FDMS-equipped PM2.5 TEOM and PM10 TEOM not corrected for semivolatile mass loss. A regression-based model was developed for removing the error in these measurements by estimating the semivolatile concentration of PM2.5 from total PM2.5 concentrations. By estimating nonvolatile PM2.5 concentrations from this relationship, PM10-2.5 was calculated as the difference between nonvolatile PM10 and PM2.5 concentrations.

Short-term effects of PM2.5, PM10 and PM2.5-10 on daily mortality in The Netherlands

INTRODUCTION

Information on the relationship between levels of particulate matter (PM) smaller than 2.5 μm and mortality rates in Europe is relatively sparse because of limited availability of PM2.5 measurement data. Even less information is available on the health effects attributable to PM2.5-10, especially for North-West Europe.

OBJECTIVES

To investigate the relationship between various PM size fractions and daily mortality rates.

METHODS

Daily concentrations of PM from the Dutch National Ambient Air Quality Monitoring Network as well as all cause and cause-specific mortality rates in The Netherlands were obtained for the period 2008-2009. Poisson regression analysis using generalized additive models was used, with adjustment for potential confounding including long-term and seasonal trends, influenza incidence, meteorological variables, day of the week, and holidays. Different measures of PM (PM2.5, PM10 and PM2.5-10) were analysed.

RESULTS

PM10 and PM2.5 levels were statistically significantly (p<0.05) associated with all cause and cause-specific deaths. For example, a 10 μg/m(3) increase in previous day PM was associated with 0.8% (95% CI 0.3-1.2) excess risk in all cause mortality for PM2.5 and a 0.6% (CI 0.2-1.0) excess risk for PM10. No appreciable associations were observed for PM2.5-10. Effects of PM10, and PM2.5 were insensitive to adjustment for PM2.5-10, and vice-versa. PM10 and PM2.5 were too highly correlated to disentangle their independent effects.

CONCLUSIONS

PM10 and PM2.5 both were significantly associated with all cause and cause-specific mortality. We were unable to demonstrate significant effects for PM2.5-10, possibly due to the lower temporal variability and the higher exposure misclassification in PM2.5-10 compared to PM10 or PM2.5. The lack of effects of PM2.5-10 in our study should therefore not be interpreted as an indication that PM2.5-10 can be considered harmless.

Chemical fingerprint and impact of shipping emissions over a western Mediterranean metropolis: primary and aged contributions

An intensive monitoring campaign was carried out in the harbor of Barcelona (Spain) to quantify the contribution of primary shipping emissions (PSE) on PM10. Chemical composition of inorganic species, as well as OC and EC, was completed, and a source apportionment analysis by Positive Matrix Factorization was conducted. Among the 6 sources extracted, two were linked to harbor emissions: dusty materials released in different areas along the harbor and fuel-oil combustion. On average, harbor emissions accounted for 31% of the PM10 mass. Since the chemical signature of PSE was not determined neither their contribution was obtained, additional approaches were followed and mainly consisted in: 1) the evaluation of V/Ni and V/Cu ratios to identify those days affected by PSE; 2) the identification of the chemical components increasing under the influence of PSE; 3) the calculation of the daily and average PSE from their experimentally-determined chemical signature and the experimental concentrations of vanadium. As a result, the contribution of PSE was estimated in 0.84 μg m(-3) (2.7% of PM10) and the residual fuel-oil combustion factor (3.6 μg m(-3), 12% of PM10) was interpreted as aged shipping emissions. The present study splits the contribution of shipping emissions into primary and aged, and highlights the importance of atmospheric mixing and aging processes in western Mediterranean atmospheres. In the case of shipping emissions, the aged products were found to be dominant with respect to the primary ones even in the vicinity of the source.

Neural network model for the prediction of PM10 daily concentrations in two sites in the Western Mediterranean

An artificial neural network (ANN) was developed and tested to forecast PM10 daily concentration in two contrasted environments in NE Spain, a regional background site (Montseny), and an urban background site (Barcelona-CSIC), which was highly influenced by vehicular emissions. In order to predict 24-h average PM10 concentrations, the artificial neural network previously developed by Caselli et al. (2009) was improved by using hourly PM concentrations and deterministic factors such as a Saharan dust alert. In particular, the model input data for prediction were the hourly PM10 concentrations 1-day in advance, local meteorological data and information about air masses origin. The forecasted performance indexes for both sites were calculated and they showed better results for the regional background site in Montseny (R(2)=0.86, SI=0.75) than for urban site in Barcelona (R(2)=0.73, SI=0.58), influenced by local and sometimes unexpected sources. Moreover, a sensitivity analysis conducted to understand the importance of the different variables included among the input data, showed that local meteorology and air masses origin are key factors in the model forecasts. This result explains the reason for the improvement of ANN's forecasting performance at the Montseny site with respect to the Barcelona site. Moreover, the artificial neural network developed in this work could prove useful to predict PM10 concentrations, especially, at regional background sites such as those on the Mediterranean Basin which are primarily affected by long-range transports. Hence, the artificial neural network presented here could be a powerful tool for obtaining real time information on air quality status and could aid stakeholders in their development of cost-effective control strategies.

Associations between fine and coarse particles and mortality in Mediterranean cities: results from the MED-PARTICLES project

BACKGROUND

Few studies have investigated the independent health effects of different size fractions of particulate matter (PM) in multiple locations, especially in Europe.

OBJECTIVES

We estimated the short-term effects of PM with aerodynamic diameter ≤ 10 μm (PM10), ≤ 2.5 μm (PM2.5), and between 2.5 and 10 μm (PM2.5-10) on all-cause, cardiovascular, and respiratory mortality in 10 European Mediterranean metropolitan areas within the MED-PARTICLES project.

METHODS

We analyzed data from each city using Poisson regression models, and combined city-specific estimates to derive overall effect estimates. We evaluated the sensitivity of our estimates to co-pollutant exposures and city-specific model choice, and investigated effect modification by age, sex, and season. We applied distributed lag and threshold models to investigate temporal patterns of associations.

RESULTS

A 10-μg/m3 increase in PM2.5 was associated with a 0.55% (95% CI: 0.27, 0.84%) increase in all-cause mortality (0-1 day cumulative lag), and a 1.91% increase (95% CI: 0.71, 3.12%) in respiratory mortality (0-5 day lag). In general, associations were stronger for cardiovascular and respiratory mortality than all-cause mortality, during warm versus cold months, and among those ≥ 75 versus < 75 years of age. Associations with PM2.5-10 were positive but not statistically significant in most analyses, whereas associations with PM10 seemed to be driven by PM2.5.

CONCLUSIONS

We found evidence of adverse effects of PM2.5 on mortality outcomes in the European Mediterranean region. Associations with PM2.5-10 were positive but smaller in magnitude. Associations were stronger for respiratory mortality when cumulative exposures were lagged over 0-5 days, and were modified by season and age.

PM₁₀ and PM₂.₅ sources at an insular location in the western Mediterranean by using source apportionment techniques

PM₁₀ and PM₂.₅ chemical composition has been determined at a suburban insular site in the Balearic Islands (Spain) during almost one and a half year. As a result, 200 samples with more than 50 chemical parameters analyzed have been obtained. The whole database has been analyzed by two receptor modelling techniques (Principal Component Analysis and Positive Matrix Factorisation) in order to identify the main PM sources. After that, regression analyses with respect to the PM mass concentrations were conducted to quantify the daily contributions of each source. Four common sources were identified by both receptor models: secondary nitrate coupled with vehicular emissions, secondary sulphate influenced by fuel-oil combustion, aged marine aerosols and mineral dust. In addition, PCA isolated harbour emissions and a mixed anthropogenic factor containing industrial emissions; whereas PMF isolated an additional mineral factor interpreted as road dust+harbour emissions, and a vehicular abrasion products factor. The use of both methodologies appeared complementary. Nevertheless, PMF sources by themselves were better differentiated. Besides these receptor models, a specific methodology to quantify African dust was also applied. The combination of these three source apportionment tools allowed the identification of 8 sources, being 4 of them mineral (African, regional, urban and harbour dusts). As a summary, 29% of PM₁₀ was attributed to natural sources (African dust, regional dust and sea spray), whereas the proportion diminished to 11% in PM₂.₅. Furthermore, the secondary sulphate source, which accounted for about 22 and 32% of PM₁₀ and PM₂.₅, is strongly linked to the aged polluted air masses residing over the western Mediterranean in the warm period.

Particulate matter concentrations during desert dust outbreaks and daily mortality in Nicosia, Cyprus

Ambient particulate matter (PM) has been shown to have short- and long-term effects on cardiorespiratory mortality and morbidity. Most of the risk is associated with fine PM (PM(2.5)); however, recent evidence suggests that desert dust outbreaks are major contributors to coarse PM (PM(10-2.5)) and may be associated with adverse health effects. The objective of this study was to investigate the risk of total, cardiovascular and respiratory mortality associated with PM concentrations during desert dust outbreaks. We used a time-series design to investigate the effects of PM(10) on total non-trauma, cardiovascular and respiratory daily mortality in Cyprus, between 1 January 2004 and 31 December 2007. Separate PM(10) effects for non-dust and dust days were fit in generalized additive Poisson models. We found a 2.43% (95% CI: 0.53, 4.37) increase in daily cardiovascular mortality associated with each 10-μg/m(3) increase in PM(10) concentrations on dust days. Associations for total (0.13% increase, 95% CI: -1.03, 1.30) and respiratory mortality (0.79% decrease, 95% CI: -4.69, 3.28) on dust days and all PM(10) and mortality associations on non-dust days were not significant. Although further study of the exact nature of effects across different affected regions during these events is needed, this study suggests adverse cardiovascular effects associated with desert dust events.

Ozone is associated with cardiopulmonary and stroke emergency hospital visits in Reykjavík, Iceland 2003-2009

BACKGROUND

Air pollution exposure is associated with hospital admissions and emergency room visits for cardiopulmonary disease and stroke. Iceland's capital area, Reykjavik, has generally low air pollution levels, but traffic and natural sources contribute to pollution levels. The objective of this study was to investigate temporal associations between emergency hospital visits and air pollutants ozone (O3), nitrogen dioxide (NO2), and particulate matter (PM10) in the Icelandic capital area.

METHODS

We constructed a time series of the daily number of adults who visited the emergency room, or were acutely admitted for stroke or cardiorespiratory causes to Landspitali University Hospital 1 January 2003 - 31 December 2009 from the hospital in-patient register. We used generalized additive models assuming Poisson distribution, to analyze the daily emergency hospital visits as a function of the pollutant levels, and adjusted for meteorological variables, day of week, and time trend with splines.

RESULTS

Daily emergency hospital visits increased 3.9% (95% confidence interval (CI) 1.7-6.1%) per interquartile (IQR) change in average O3 the same and two previous days. For females, the increase was 7.8% (95% CI 3.6-12.1) for elderly (70+), the increase was 3.9% (95% CI 0.6-7.3%) per IQR increase of NO2. There were no associations with PM10.

CONCLUSIONS

We found an increase in daily emergency hospital visits associated with O3, indicating that low-level exposure may trigger cardiopulmonary events or stroke.

Impact of Sahara dust transport on Cape Verde atmospheric element particles

The objectives of this study were to (1) conduct an elemental characterization of airborne particles sampled in Cape Verde and (2) assess the influence of Sahara desert on local suspended particles. Particulate matter (PM(10)) was collected in Praia city (14°94'N; 23°49'W) with a low-volume sampler in order to characterize its chemical composition by k0-INAA. The filter samples were first weighed and subsequently irradiated at the Portuguese Research Reactor. Results showed that PM(10) concentrations in Cape Verde markedly exceeded the health-based air quality standards defined by the European Union (EU), World Health Organization (WHO), and U.S. Environmental Protection Agency (EPA), in part due to the influence of Sahara dust transport. The PM(10) composition was characterized essentially by high concentrations of elements originating from the soil (K, Sm, Co, Fe, Sc, Rb, Cr, Ce, and Ba) and sea (Na), and low concentrations of anthropogenic elements (As, Zn, and Sb). In addition, the high concentrations of PM measured in Cape Verde suggest that health of the population may be less affected compared with other sites where PM(10) concentrations are lower but more enriched with toxic elements.

Desert dust impacts on human health: an alarming worldwide reality and a need for studies in West Africa

High desert dust concentrations raise concerns about adverse health effects on human populations. Based on a systematic literature review, this paper aims to learn more about the relationship between desert dust and human health in the world and to analyse the place of West Africa as a study area of interest. Papers focussing on the potential relationship between dust and health and showing quantitative analyses, published between January 1999 and September 2011, were identified using the ISI Web of Knowledge database (N = 50). A number of adverse health effects, including respiratory, cardiovascular and cardiopulmonary diseases, are associated with dust. This survey highlights obvious dust impacts on human health independently of the study area, health outcomes and method. Moreover, it reveals an imbalance between the areas most exposed to dust and the areas most studied in terms of health effects. None of these studies has been conducted in West Africa, despite the proximity of the Sahara, which produces about half of the yearly global mineral dust. In view of the alarming results in many parts of the world (Asia, Europe, America), this paper concludes by stressing the importance of carrying out impact studies of Saharan dust in West Africa, where dust events are more frequent and intense than anywhere else.

A cautionary note to prevent the heat effects on human health

The deaths of two British tourists caused by heat in the island of Gran Canaria last May while conducting outdoor physical exercise leads us to make several reflections. We discuss the subject on, the adaptation of the people to the heat, the vulnerability of individuals over 65 years and the effectiveness of prevention plans against heat waves. This study questions the appropriateness of the activation timing of these plans by the Ministry of Health, Social Services and Equality, and also questions the temperature thresholds established for their implementation.

Influences of natural emission sources (wildfires and Saharan dust) on the urban organic aerosol in Barcelona (Western Mediterranean Basis) during a PM event

The urban air quality in Barcelona in the Western Mediterranean Basin is characterized by overall high particulate matter (PM) concentrations, due to intensive local anthropogenic emissions and specific meteorological conditions. Moreover, on several days, especially in summer, natural PM sources, such as long-range transported Saharan dust from Northern Africa or wildfires on the Iberian Peninsula and around the Mediterranean Basin, may influence the levels and composition of the organic aerosol. In the second half of July 2009, daily collected PM(10) filter samples in an urban background site in Barcelona were analyzed on organic tracer compounds representing several emission sources. During this period, an important PM peak event was observed. Individual organic compound concentrations increased two to five times during this event. Although highest increase was observed for the organic tracer of biomass burning, the contribution to the organic aerosol was estimated to be around 6 %. Organic tracers that could be related to Saharan dust showed no correlation with the PM and OC levels, while this was the case for those related to fossil fuel combustion from traffic emissions. Moreover, a change in the meteorological conditions gave way to an overall increase of the urban background contamination. Long-range atmospheric transport of organic compounds from primary emissions sources (i.e., wildfires and Saharan dust) has a relatively moderate impact on the organic aerosol in an urban area where the local emissions are dominating.

Saharan dust, particulate matter and cause-specific mortality: a case-crossover study in Barcelona (Spain)

BACKGROUND

Studies measuring health effects of Saharan dust based on large particulate matter (PM) fraction groups may be masking some effects. Long distant transport reduces the amount of heavier and larger particles in the Saharan air masses increasing the relative contribution of smaller particles that may be more innocuous. This study investigates the association between different PM fractions and daily mortality during Saharan and non-Saharan days in Barcelona, Spain.

METHODS

We collected daily PM(1), PM(2.5-1) and PM(10-2.5) fractions, and cause-specific mortality (cardiovascular, respiratory and cerebrovascular) between March 2003 and December 2007. Changes of effects between Saharan and non-Saharan dust days were assessed using a time-stratified case-crossover design.

RESULTS

During non-Saharan dust days we found statistically significant (p<0.05) effects of PM(10-2.5) for cardiovascular (odds ratio for increase of an interquartile range, OR=1.033, 95% confidence interval: 1.006-1.060) and respiratory mortality (OR=1.044, 95% CI: 1.001-1.089). During Saharan dust days strongest cardiovascular effects were found for the same fraction (OR=1.085, 95% CI: 1.017-1.158) with an indication of effect modification (p=0.111). Effects of PM(2.5-1) during Saharan dust days were about the double than in non-dust days for cardiovascular and respiratory mortality, but these differences were not statistically significant.

CONCLUSION

Our results using independent fractions of PMs provide further evidence that the effects of short-term exposure to PM during Saharan dust days are associated with both cardiovascular and respiratory mortality. A better understanding of which of the different PM size fractions brought by Saharan dust is more likely to accelerate adverse effects may help better understand mechanisms of toxicity.

Health effects from Sahara dust episodes in Europe: literature review and research gaps

The adverse consequences of particulate matter (PM) on human health have been well documented. Recently, special attention has been given to mineral dust particles, which may be a serious health threat. The main global source of atmospheric mineral dust is the Sahara desert, which produces about half of the annual mineral dust. Sahara dust transport can lead to PM levels that substantially exceed the established limit values. A review was undertaken using the ISI web of knowledge database with the objective to identify all studies presenting results on the potential health impact from Sahara dust particles. The review of the literature shows that the association of fine particles, PM₂.₅, with total or cause-specific daily mortality is not significant during Saharan dust intrusions. However, regarding coarser fractions PM₁₀ and PM₂.₅₋₁₀ an explicit answer cannot be given. Some of the published studies state that they increase mortality during Sahara dust days while other studies find no association between mortality and PM₁₀ or PM₂.₅₋₁₀. The main conclusion of this review is that health impact of Saharan dust outbreaks needs to be further explored. Considering the diverse outcomes for PM₁₀ and PM₂.₅₋₁₀, future studies should focus on the chemical characterization and potential toxicity of coarse particles transported from Sahara desert mixed or not with anthropogenic pollutants. The results of this review may be considered to establish the objectives and strategies of a new European directive on ambient air quality. An implication for public policy in Europe is that to protect public health, anthropogenic sources of particulate pollution need to be more rigorously controlled in areas highly impacted by the Sahara dust.

Dust storms and the risk of asthma admissions to hospitals in Kuwait

OBJECTIVE

Arid areas in the Arabian Peninsula are one of the largest sources of global dust, yet there is no data on the impact of this on human health. This study aimed to investigate the impact of dust storms on hospital admissions due to asthma and all respiratory diseases over a period of 5 years in Kuwait.

METHODS

A population-based retrospective time series study of daily emergency asthma admissions and admissions due to respiratory causes in public hospitals in Kuwait was analyzed in relation to dust storm events. Dust storm days were defined as the mean daily PM(10)>200 μg/m(3) based on measurements obtained from all six monitoring sites in the country.

FINDINGS

During the five-year study period, 569 (33.6%) days had dust storm events and they were significantly associated with an increased risk of same-day asthma and respiratory admission, adjusted relative risk of 1.07 (95% CI: 1.02-1.12) and 1.06 (95% CI: 1.04-1.08), respectively. This was particularly evident among children.

CONCLUSION

Dust storms have a significant impact on respiratory and asthma admissions. Evidence is more convincing and robust compared to that from other geographical settings which highlights the importance of public health measures to protect people's health during dust storms and reduce the burden on health services due to dust events.

Daily effects of air pollutants and pollen types on asthma and COPD hospital emergency visits in the industrial and Mediterranean Spanish city of Cartagena

BACKGROUND

Associations found in time-series studies on hospital emergency room (ER) visits due to asthma and chronic obstructive pulmonary disease (COPD) with single air pollutants show some lack of consistency. The respiratory effects of aeroallergens in the air pollution mix are not well established. Non-linear relationships of different airborne pollen types with certain respiratory diseases have also been described. We aim to study the short-term effects of major air pollutants and aeroallergen pollen on asthma and COPD hospital ER visits in the industrial and Mediterranean Spanish city of Cartagena during 1995-1998.

METHODS

The association of asthma and COPD to ER visits with mean levels of sulphur and nitrogen dioxides (SO(2) and NO(2)), total suspended particles (TSP), ozone (O(3)), and the main allergenic airborne pollen types were analysed using Poisson regression with Generalised Additive Models, taking into account delayed effects and adjusting for long-term trends, seasonality, weather conditions, holidays and flu notifications.

RESULTS

Multipollutant models showed a similar relative risk (RR) increase (in %), of around 5% in asthma and COPD ER visits per 10 μg/m(3) SO(2) increments. The risk of an ER visit for the same NO(2) increment was 2.6% for asthma and 3.3% for COPD. Visits to the ER due to asthma showed a positive increase with both Urticaceae and Poaceae levels, but did not substantially modify the previous percentages.

CONCLUSIONS

Air levels of SO(2) and NO(2) were associated with a substantial increased risk in ER visits due to asthma and COPD. The inclusion of Poaceae and Urticaceae pollen did not alter that association.

The effects of the 2009 dust storm on emergency admissions to a hospital in Brisbane, Australia

In September 2009 an enormous dust storm swept across eastern Australia. Dust is potentially hazardous to health as it interferes with breathing, and previous dust storms have been linked to increased risks of asthma and even death. We examined whether the 2009 Australian dust storm changed the volume or characteristics of emergency admissions to hospital. We used an observational study design, using time series analyses to examine changes in the number of admissions, and case-only analyses to examine changes in the characteristics of admissions. The admission data were from the Prince Charles Hospital, Brisbane, between 1 January 2009 and 31 October 2009. There was a 39% increase in emergency admissions associated with the storm (95% confidence interval: 5, 81%), which lasted for just 1 day. The health effects of the storm could not be detected using particulate matter levels. We found no significant change in the characteristics of admissions during the storm; specifically, there was no increase in respiratory admissions. The dust storm had a short-lived impact on emergency hospital admissions. This may be because the public took effective avoidance measures, or because the dust was simply not toxic, being composed mainly of soil. Emergency departments should be prepared for a short-term increase in admissions during dust storms.

Source apportionment of total suspended particulates in an arid area in southwestern Iran using positive matrix factorization

The present study sough to apportion the possible sources of TSP in Ahvaz, southwestern Iran. A high correlation coefficient existed between measured and predicted values (R(2) = 0.99), indicating that the data were well modeled. Seven factors were resolved by the model: crustal dust (56%), road dust (7%), motor vehicles (8%), marine aerosol (9%), secondary aerosol (7%), metallurgical plants (4.5%), and finally petrochemical plants & fossil fuel combustion (8.5%). In contrast with crustal dust having higher relative contributions during spring and summer, motor vehicles had higher contributions during fall and winter. In addition, the latter had higher contributions during weekdays than weekends.

Single-particle SEM-EDX analysis of iron-containing coarse particulate matter in an urban environment: sources and distribution of iron within Cleveland, Ohio

The physicochemical properties of coarse-mode, iron-containing particles and their temporal and spatial distributions are poorly understood. Single-particle analysis combining X-ray elemental mapping and computer-controlled scanning electron microscopy (CCSEM-EDX) of passively collected particles was used to investigate the physicochemical properties of iron-containing particles in Cleveland, OH, in summer 2008 (Aug-Sept), summer 2009 (July-Aug), and winter 2010 (Feb-March). The most abundant classes of iron-containing particles were iron oxide fly ash, mineral dust, NaCl-containing agglomerates (likely from road salt), and Ca-S containing agglomerates (likely from slag, a byproduct of steel production, or gypsum in road salt). The mass concentrations of anthropogenic fly ash particles were highest in the Flats region (downtown) and decreased with distance away from this region. The concentrations of fly ash in the Flats region were consistent with interannual changes in steel production. These particles were observed to be highly spherical in the Flats region, but less so after transport away from downtown. This change in morphology may be attributed to atmospheric processing. Overall, this work demonstrates that the method of passive collection with single-particle analysis by electron microscopy is a powerful tool to study spatial and temporal gradients in components of coarse particles. These gradients may correlate with human health effects associated with exposure to coarse-mode particulate matter.

Association between dust weather and number of admissions for patients with respiratory diseases in spring in Lanzhou

Controlling the confounding factors on respiratory hospitalizations such as long-term trend, meteorological factor, atmospheric pollution, and calendar effect, the research is designed to study the effect of sand-dust weather on respiratory diseases from 2001 to 2005 in Lanzhou City on the basis of the semi-parametric generalized additive model (GAM). The results indicate that there is an association between sand-dust weather and the increase in respiratory hospitalizations, and with lagging effect. There are gender and age differences in the effect of sand-dust weather on health, on male severer than on female (RR value being 1.148 for male, while 1.144 for female without statistical significance), and much greater on the aged ≥ 65 years than on < 65 years (RR value being 1.266 for ≥ 65 yr, and 1.119 for < 65 yr).

Intra-urban air pollution in a rapidly growing Sahelian city

In this paper we analyze spatial and temporal variations of air pollution (PM(1), PM(2.5), PM(10), CO, NO(x), O(3), Toluene and Benzene) and climate in areas of different development typology in Ouagadougou, Burkina Faso. Analyses are based on measurements from fixed sites and car traverse measurements during field studies in 2007 and 2010. Large spatial and temporal variations were found, showing a generally poor air quality situation, with extreme levels of PM(10), commonly exceeding air quality guidelines of WHO. Pollution levels increase considerably with increased atmospheric stability. Important sources were transported dust and re-suspension of dust from unpaved roads, but also traffic emissions and biomass burning. The spatial variations are examined with focus on effects for variations in potential exposure depending on for example area of residence and daily activity pattern, showing that great differences are likely to exist. Ouagadougou, like most developing countries worldwide, currently experiences an extremely rapid population growth in combination with limited financial means. This is likely to create increasingly harmful air pollution situations for the rapidly growing populations of these areas, and shows an urgent need for increased understanding of the pollution situation as well as development of mitigation strategies.

Saharan dust and association between particulate matter and case-specific mortality: a case-crossover analysis in Madrid (Spain)

BACKGROUND

Saharan dust intrusions are a common phenomenon in the Madrid atmosphere, leading induce exceedances of the 50 μg/m(3)--EU 24 h standard for PM10.

METHODS

We investigated the effects of exposure to PM(10) between January 2003 and December 2005 in Madrid (Spain) on daily case-specific mortality; changes of effects between Saharan and non-Saharan dust days were assessed using a time-stratified case-crossover design.

RESULTS

Saharan dust affected 20% of days in the city of Madrid. Mean concentration of PM(10) was higher during dust days (47.7 μg/m(3)) than non-dust days (31.4 μg/m(3)). The rise of mortality per 10 μg/m(3) PM(10) concentration were always largely for Saharan dust-days. When stratifying by season risks of PM(10), at lag 1, during Saharan dust days were stronger for respiratory causes during cold season (IR% = 3.34% (95% CI: 0.36, 6.41) versus 2.87% (95% CI: 1.30, 4.47)) while for circulatory causes effects were stronger during warm season (IR% = 4.19% (95% CI: 1.34, 7.13) versus 2.65% (95% CI: 0.12, 5.23)). No effects were found for cerebrovascular causes.

CONCLUSIONS

We found evidence of strongest effects of particulate matter during Saharan dust days, providing a suggestion of effect modification, even though interaction terms were not statistically significant. Further investigation is needed to understand the mechanism by which Saharan dust increases mortality.

Estimated short-term effects of coarse particles on daily mortality in Stockholm, Sweden

BACKGROUND

Although serious health effects associated with particulate matter (PM) with aerodynamic diameter ≤ 10 μm (PM₁₀) and ≤ 2.5 μm (PM(2.5); fine fraction) are documented in many studies, the effects of coarse PM (PM(2.5-10)) are still under debate.

OBJECTIVE

In this study, we estimated the effects of short-term exposure of PM(2.5-10) on daily mortality in Stockholm, Sweden.

METHOD

We collected data on daily mortality for the years 2000 through 2008. Concentrations of PM₁₀, PM(2.5), ozone, and carbon monoxide were measured simultaneously in central Stockholm. We used additive Poisson regression models to examine the association between daily mortality and PM2.5-10 on the day of death and the day before. Effect estimates were adjusted for other pollutants (two-pollutant models) during different seasons.

RESULTS

We estimated a 1.68% increase [95% confidence interval (CI): 0.20%, 3.15%] in daily mortality per 10-μg/m³ increase in PM(2.5-10) (single-pollutant model). The association with PM(2.5-10) was stronger for November through May, when road dust is most important (1.69% increase; 95% CI: 0.21%, 3.17%), compared with the rest of the year (1.31% increase; 95% CI: -2.08%, 4.70%), although the difference was not statistically significant. When adjusted for other pollutants, particularly PM(2.5), the effect estimates per 10 μg/m³ for PM(2.5-10) decreased slightly but were still higher than corresponding effect estimates for PM(2.5).

CONCLUSIONS

Our analysis shows an increase in daily mortality associated with elevated urban background levels of PM(2.5-10). Regulation of PM(2.5-10) should be considered, along with actions to specifically reduce PM(2.5-10) emissions, especially road dust suspension, in cities.

Hydrogen sulfide and particle matter levels associated with increased dispensing of anti-asthma drugs in Iceland's capital

BACKGROUND

Air pollutants in Iceland's capital area include hydrogen sulfide (H2S) emissions from geothermal power plants, particle pollution (PM10) and traffic-related pollutants. Respiratory health effects of exposure to PM and traffic pollutants are well documented, yet this is one of the first studies to investigate short-term health effects of ambient H2S exposure.

OBJECTIVES

The aim of this study was to investigate the associations between daily ambient levels of H2S, PM10, nitrogen dioxide (NO2) and ozone (O3), and the use of drugs for obstructive pulmonary diseases in adults in Iceland's capital area.

METHODS

The study period was 8 March 2006 to 31 December 2009. We used log-linear Poisson generalized additive regression models with cubic splines to estimate relative risks of individually dispensed drugs by air pollution levels. A three-day moving average of the exposure variables gave the best fit to the data. Final models included significant covariates adjusting for climate and influenza epidemics, as well as time-dependent variables.

RESULTS

The three-day moving average of H2S and PM10 levels were positively associated with the number of individuals who were dispensed drugs at lag 3-5, corresponding to a 2.0% (95% confidence interval [CI] 0.4, 3.6) and 0.9% (95% CI 0.1, 1.8) per 10 μg/m3 pollutant concentration increase, respectively.

CONCLUSION

Our findings indicated that intermittent increases in levels of particle matter from traffic and natural sources and ambient H2S levels were weakly associated with increased dispensing of drugs for obstructive pulmonary disease in Iceland's capital area. These weak associations could be confounded by unevaluated variables hence further studies are needed.

Exposure assessment for estimation of the global burden of disease attributable to outdoor air pollution

Ambient air pollution is associated with numerous adverse health impacts. Previous assessments of global attributable disease burden have been limited to urban areas or by coarse spatial resolution of concentration estimates. Recent developments in remote sensing, global chemical-transport models, and improvements in coverage of surface measurements facilitate virtually complete spatially resolved global air pollutant concentration estimates. We combined these data to generate global estimates of long-term average ambient concentrations of fine particles (PM(2.5)) and ozone at 0.1° × 0.1° spatial resolution for 1990 and 2005. In 2005, 89% of the world's population lived in areas where the World Health Organization Air Quality Guideline of 10 μg/m(3) PM(2.5) (annual average) was exceeded. Globally, 32% of the population lived in areas exceeding the WHO Level 1 Interim Target of 35 μg/m(3), driven by high proportions in East (76%) and South (26%) Asia. The highest seasonal ozone levels were found in North and Latin America, Europe, South and East Asia, and parts of Africa. Between 1990 and 2005 a 6% increase in global population-weighted PM(2.5) and a 1% decrease in global population-weighted ozone concentrations was apparent, highlighted by increased concentrations in East, South, and Southeast Asia and decreases in North America and Europe. Combined with spatially resolved population distributions, these estimates expand the evaluation of the global health burden associated with outdoor air pollution.

Characterizing mortality effects of particulate matter size fractions in the two capital cities of the Canary Islands

Most of the studies differentiating the effect of size-classified particulate matter (PM) exposure have been carried out in cities where the average levels of fine particles (PM(2.5)) were higher than those of coarse particles (PM(10-2.5)). These studies have suggested that PM(2.5) is associated with daily mortality, but there is only limited evidence that PM(10-2.5) is independently associated with mortality. The citizens of the Canary Islands are exposed to PM which is highly influenced by mineral dust because of the islands' proximity to the Western Coast of Morocco. This offers an excellent opportunity to analyze in detail the short-term association between PM size fractions and total, respiratory and heart disease mortality. A time-series study from 2001 to 2004 was carried out. For each PM size fraction and mortality outcome, Generalized Additive Poisson Model was performed controlling for potential confounding. Different lag structures, unconstrained distributed lag models and two-pollutant models were examined. After assessing the linearity in the relationship, a piecewise linear analysis for exploring the existence of different slopes for different ranges of PM was carried out. The 10 μg/m(3) increase in PM(2.5) and PM(10-2.5) levels was associated with a 7.5% (95% confidence interval=0.4-15.0) and a 7.4 (95% CI=1.5-13.7) increase in heart and respiratory disease mortality, respectively. Spline curves were quite linear over the PM concentrations seen on most days (dominated by combustion sources) in these cities, meanwhile on days with higher particulate levels (natural sources) a risk increase above certain PM levels was found, suggesting a curvilinear association and that, at least in some locations, PM(10-2.5) can play an important role in PM-related toxicity. The overall findings suggest that the establishment of new air quality standards for the short-term effect of PM(2.5) and PM(10-2.5) and further limiting levels of PM(10) in European Union is advisable.

Short-term effects of particulate matter on total mortality during Saharan dust outbreaks: a case-crossover analysis in Madrid (Spain)

BACKGROUND

The role of Saharan dust outbreaks on the relationship between particulate matter and daily mortality has recently been addressed in studies conducted in Southern Europe, although they have not given consistent results.

METHODS

We investigated the effects of coarse (PM(10-2.5)) and fine particulate matter (PM(2.5)) in Madrid on total mortality during Saharan dust and non-dust days using a case-crossover design.

RESULTS

During Saharan dust days, an increase of 10mg/m(3) of PM(10-2.5) raised total mortality by 2.8% compared with 0.6% during non-dust days (P-value for interaction=0.0165).

CONCLUSION

We found evidence of stronger adverse health effects of PM(10-2.5) during Saharan dust outbreaks effects for impacted European populations, but not for PM(2.5). Further research is needed to understand mechanisms by which Saharan dust increases risk of mortality.

Nanowired drug delivery for neuroprotection in central nervous system injuries: modulation by environmental temperature, intoxication of nanoparticles, and comorbidity factors

Recent developments in nanomedicine resulted in targeted drug delivery of active compounds into the central nervous system (CNS) either through encapsulated material or attached to nanowires. Nanodrug delivery by any means is supposed to enhance neuroprotection due to rapid accumulation of drugs within the target area and a slow metabolism of the compound. These two factors enhance neuroprotection than the conventions drug delivery. However, this is still uncertain whether nanodrug delivery could alter the pharmacokinetics of compounds making it more effective or just longer exposure of the compound for extended period of time is primarily responsible for enhanced effects of the drugs. Our laboratory is engaged in understanding of the nanodrug delivery using TiO(2) nanowires in CNS injuries models, for example, spinal cord injury (SCI), hyperthermia and/or intoxication of nanoparticles with or without other comorbidity factors, that is, diabetes or hypertension in rat models. Our observations suggest that nanowired drug delivery is effective under normal situation of SCI and hyperthermia as evidenced by significant reduction in the blood-brain barrier (BBB) breakdown, brain edema formation, cognitive disturbances, neuronal damages, and brain pathologies. However, when the pathophysiology of these CNS injuries is aggravated by nanoparticles intoxication or comorbidity factors, adjustment in dosage of nanodrug delivery is needed. This indicates that further research in nanomedicine is needed to explore suitable strategies in achieving greater neuroprotection in CNS injury in combination with nanoparticles intoxication or other comorbidity factors for better clinical practices.

The effects of particulate matter sources on daily mortality: a case-crossover study of Barcelona, Spain

BACKGROUND

Dozens of studies link acute exposure to particulate matter (PM) air pollution with premature mortality and morbidity, but questions remain about which species and sources in the vast PM mixture are responsible for the observed health effects. Although a few studies exist on the effects of species and sources in U.S. cities, European cities-which have a higher proportion of diesel engines and denser urban populations-have not been well characterized. Information on the effects of specific sources could aid in targeting pollution control and in articulating the biological mechanisms of PM.

OBJECTIVES

Our study examined the effects of various PM sources on daily mortality for 2003 through 2007 in Barcelona, a densely populated city in the northeast corner of Spain.

METHODS

Source apportionment for PM ≤ 2.5 μm and ≤ 10 µm in aerodynamic diameter (PM2.5 and PM10) using positive matrix factorization identified eight different factors. Case-crossover regression analysis was used to estimate the effects of each factor.

RESULTS

Several sources of PM2.5, including vehicle exhaust, fuel oil combustion, secondary nitrate/organics, minerals, secondary sulfate/organics, and road dust, had statistically significant associations (p < 0.05) with all-cause and cardiovascular mortality. Also, in some cases relative risks for a respective interquartile range increase in concentration were higher for specific sources than for total PM2.5 mass.

CONCLUSIONS

These results along with those from our multisource models suggest that traffic, sulfate from shipping and long-range transport, and construction dust are important contributors to the adverse health effects linked to PM.

The oxidative potential and biological effects induced by PM10 obtained in Mexico City and at a receptor site during the MILAGRO Campaign

As part of a field campaign that studied the impact of Mexico City pollution plume at the local, sub-regional and regional levels, we studied transport-related changes in PM(10) composition, oxidative potential and in vitro toxicological patterns (hemolysis, DNA degradation). We collected PM(10) in Mexico City (T(0)) and at a suburban-receptor site (T(1)), pooled according to two observed ventilation patterns (T(0) → T(1) influence and non-influence). T(0) samples contained more Cu, Zn, and carbon whereas; T(1) samples contained more of Al, Si, P, S, and K (p < 0.05). Only SO(4)(-2) increased in T(1) during the influence periods. Oxidative potential correlated with Cu/Zn content (r = 0.74; p < 0.05) but not with biological effects. T(1) PM(10) induced greater hemolysis and T(0) PM(10) induced greater DNA degradation. Influence/non-influence did not affect oxidative potential nor biological effects. Results indicate that ventilation patterns had little effect on intrinsic PM(10) composition and toxicological potential, which suggests a significant involvement of local sources.

A case-crossover analysis of Asian dust storms and mortality in the downwind areas using 14-year data in Taipei

This study aims to assess the association between Asian dust storms (ADS) and daily mortality in Taipei, Taiwan. A time-stratified case-crossover design was used to investigate the effects of ADS on mortality. Odds ratios (ORs) of total non-accidental (ICD-9 <800), cardiovascular (ICD-9 390-459, 785), and respiratory deaths (ICD-9 460-519, 786) were estimated for residents in Taipei metropolis over a 14-year study period between 1994 and 2007 by conditional logistic regression. Air pollution levels and temperature data were recorded by a network of 16 monitoring stations spreading around Taipei. Compared with reference days, particulate matter with aerodynamic diameter less than 10 and 2.5μm (PM(10) and PM(2.5)) increased statistically significantly by 24.2μg/m(3) and 7.9μg/m(3) per dust day, respectively. There were also statistically significant increases in sulfur dioxide (SO(2)) and ozone (O(3)) but decreases in temperature during ADS. Excess deaths were increased significantly for residents of all ages for total non-accidental deaths, with OR=1.019 (95% CI 1.003-1.035), and also for residents above 65years old, with OR=1.025 (95% CI 1.006-1.044) for total non-accidental deaths and OR=1.045 (95% CI 1.0011-1.081) for cardiovascular deaths, respectively but not for respiratory deaths during ADS. Such increases in mortality remained statistically significant in the regression models with either SO(2) or O(3). This study found that acute exposure to long-range transported Asian dust can increase the number of non-accidental and cardiovascular deaths for people of all ages and the elderly population aged above 65 on the dust storm days in Taipei, Taiwan. Further studies are still needed to find out whether mass concentrations alone or specific components in PM are responsible for excess cardiovascular deaths by ADS.