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Dust Storms, Human Health and a Global Early Warning System

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Abstract

Arid regions, the source of most airborne mineral dusts, comprise a third of the Earth’s land surface, where some two billion people are exposed daily to the fine particles raised by wind. Crossing political borders and travelling on air currents around the world, these particles not only affect the health of local communities, but also put many other populations extant at risk for cardiovascular and respiratory illnesses and a host of other health problems. Risks of exposure are affected by climatic conditions and their local and regional weather characteristics. And today, because of advancements in science and technology we are at the threshold of significantly reducing these health problems. Examples of meningitis, asthma and Valley fever are used to illustrate how risks may be lowered through a Dust-Health Early Warning System. A little more than a half-century of dedicated measurements of particulate air quality and of environmental science enhanced by Earth-orbiting satellites reveal the truth of airborne dust extent, and much of its variability in time and space. These truths have been essential in advancing numerical, dynamical models of the atmosphere that mimic and predict weather systems that loft the airborne dusts that medical sciences and epidemiology are proving harmful. This union of scientific disciplines and services makes possible today a means to improve public health around the world through a Global Dust-Health Early Warning System.

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... And, as the following discussion will show, observations must keep pace with modelling. Models that now forecast and simulate downwind mineral fractions (Nickovic et al. 2012;Nickovic et al. 2013) The Centre proposes to restart operation of the Dust Regional Atmospheric Model (DREAM/NMM -a dust storm simulation model to simulate spore emission, transport and deposition) over the US Southwest and northern Mexico Sprigg 2016), principally for Valley fever, asthma and cardiovascular epidemiology, and risk avoidance. A next step for the Caribbean would integrate and downscale DREAM/ NMM with the Africa dust plume forecasts to achieve high spatial resolution (<3 km) dust forecasts across the Caribbean, including Trinidad and the northern reaches of South America, to Florida and west into Central America. ...
... Two categories of D-HEWS warnings from the perspective of SDS-WAS objectives are described in Sprigg (2016), where precepts for the D-HEWS are developed further. An example of the first category is medium-range forecasts and tracking of dust plumes off the Sahara Desert that affect air quality, asthma and other respiratory and cardiovascular complications from Barbados to Florida and westward (e.g., Molinie 2015). ...
Technical Report
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8. Appendix: Case Studies
... And, as the following discussion will show, observations must keep pace with modelling. Models that now forecast and simulate downwind mineral fractions (Nickovic et al. 2012;Nickovic et al. 2013) The Centre proposes to restart operation of the Dust Regional Atmospheric Model (DREAM/NMM -a dust storm simulation model to simulate spore emission, transport and deposition) over the US Southwest and northern Mexico Sprigg 2016), principally for Valley fever, asthma and cardiovascular epidemiology, and risk avoidance. A next step for the Caribbean would integrate and downscale DREAM/ NMM with the Africa dust plume forecasts to achieve high spatial resolution (<3 km) dust forecasts across the Caribbean, including Trinidad and the northern reaches of South America, to Florida and west into Central America. ...
... Two categories of D-HEWS warnings from the perspective of SDS-WAS objectives are described in Sprigg (2016), where precepts for the D-HEWS are developed further. An example of the first category is medium-range forecasts and tracking of dust plumes off the Sahara Desert that affect air quality, asthma and other respiratory and cardiovascular complications from Barbados to Florida and westward (e.g., Molinie 2015). ...
... Notable examples include the Regional Master Plan for prevention and control of dust and sand storms in northeast Asia, involving the governments of China, Japan, Mongolia and South Korea (UNCCD, 2005), and the creation in Barcelona of a regional dust forecasting centre for Northern Africa, the Middle East and Europe (Terradellas, 2015). There are plans to introduce a Global Dust-Health Early Warning System (Sprigg, 2016). ...
... Dust suspended in the atmosphere has implications for human health due to its physical, chemical and biological properties and this is one of the best studied aspects of desert dust hazards (Griffin, 2007;Sandstrom and Forsberg, 2008;Goudie, 2014;Sprigg, 2016). Exposure to dust in the atmosphere can result in conjunctivitis and dermatological disorders while inhalation can cause respiratory illnesses such as silicosis (also known as desert lung syndrome) and act as a trigger for many others, including asthma, bronchitis, emphysema and chronic obstructive pulmonary disease. ...
Article
Dust storms originate in many of the world’s drylands and frequently present hazards to human society, both within the drylands themselves but also outside drylands due to long-range transport of aeolian sediments. Major sources of desert dust include the Sahara, the Middle East, central and eastern Asia, and parts of Australia, but dust-raising occurs all across the global drylands and, on occasion, beyond. Dust storms occur throughout the year and they vary in frequency and intensity over a number of timescales. Long-range transport of desert dust typically takes place along seasonal transport paths. Desert dust hazards are here reviewed according to the three phases of the wind erosion system: where dust is entrained, during the transport phase, and on deposition. This paper presents a synthesis of these hazards. It draws on empirical examples in physical geography, medical geology and geomorphology to discuss case studies from all over the world and in various fields. These include accelerated soil erosion in agricultural zones – where dust storms represent a severe form of accelerated soil erosion – the health effects of air pollution caused by desert aerosols via their physical, chemical and biological properties, transport accidents caused by poor visibility during desert dust events, and impacts on electricity generation and distribution. Given the importance of desert dust as a hazard to human societies, it is surprising to note that there have been relatively few attempts to assess their impact in economic terms. Existing studies in this regard are also reviewed, but the wide range of impacts discussed in this paper indicates that desert dust storms deserve more attention in this respect.
... Anderson (2013) reported 150,000 cases/year in US. According to Sprigg (2016) the exact location of these endemic fungi in North America is poorly known, but these occur in alternately damp and dry soils of hot areas of US. Also according to this author, it is clear that the Coccidioides fragments (3-5 μm) might be transported with dust, from North American desert areas to neighbouring populated areas, and he gave a number of references reporting of dust-Valley fever outbreaks in Mexico and Southern US regions, reaching even the Washington State (Litvintseva et al., 2015). ...
... The broad spatial pattern and seasonality of meningitis epidemics in the African Sahel (Sultan et al., 2005;Martigny and Chiapello, 2013) suggests that certain environmental factors, such as low absolute humidity (Cheesbrough et al., 1995;Molesworth et al., 2003) and relative humidity (Dukic et al., 2012), temperature (Dukic et al., 2012) and dusty atmospheric conditions (Sultan et al., 2005;Thomson et al., 2006Thomson et al., , 2009Agier et al., 2013;Deroubaix et al., 2013;Pérez García-Pando et al., 2014;Sprigg, 2016) play an important role. Identifying the specific climate factors that drive meningitis epidemics is challenging because many environmental variables have a prominent seasonal cycle that co-varies with disease incidence, and the effects of climate and dust on the pathogenesis and transmission of the bacteria have not been studied in vivo. ...
Article
We review the major features of desert dust outbreaks that are relevant to the assessment of dust impacts upon human health. Our ultimate goal is to provide scientific guidance for the acquisition of relevant population exposure information for epidemiological studies tackling the short and long term health effects of desert dust. We first describe the source regions and the typical levels of dust particles in regions close and far away from the source areas, along with their size, composition, and bio-aerosol load. We then describe the processes by which dust may become mixed with anthropogenic particulate matter (PM) and/or alter its load in receptor areas. Short term health effects are found during desert dust episodes in different regions of the world, but in a number of cases the results differ when it comes to associate the effects to the bulk PM, the desert dust-PM, or non-desert dust-PM. These differences are likely due to the different monitoring strategies applied in the epidemiological studies, and to the differences on atmospheric and emission (natural and anthropogenic) patterns of desert dust around the world. We finally propose methods to allow the discrimination of health effects by PM fraction during dust outbreaks, and a strategy to implement desert dust alert and monitoring systems for health studies and air quality management. Keywords: Mineral dust, Atmospheric particulate matter, Aerosols, Epidemiology, Natural and anthropogenic contributions
... The biological agents (e.g., fungi, bacteria, and viruses) and the mineral and chemical compositions of dust, such as silicate, carbonates, oxides, sulfates, mercury, cadmium, arsenic, and salts, may have adverse effects on human health and quality of life. There are many studies of desert dust storms and health risks (Griffin, 2007;Sandstrom and Forsberg, 2008;Goudie, 2014;Sprigg, 2016;Jeon et al., 2011;Soleimani et al., 2016;Kellogg et al., 2004). As illustrated in Table 2, many studies have shown that desert dusts are associated with mortality and morbidity due to respiratory diseases (e.g., asthma, pneumonia, rhinitis, tracheitis, silicosis, and coccidiomycosis), cardiovascular diseases (arrhythmia, ischemic heart disease, stroke, and cerebrovascular disease), cardiopulmonary diseases (chronic obstructive pulmonary disease), and injuries and death from transport accidents caused by poor visibility. ...
... As illustrated in Table 2, many studies have shown that desert dusts are associated with mortality and morbidity due to respiratory diseases (e.g., asthma, pneumonia, rhinitis, tracheitis, silicosis, and coccidiomycosis), cardiovascular diseases (arrhythmia, ischemic heart disease, stroke, and cerebrovascular disease), cardiopulmonary diseases (chronic obstructive pulmonary disease), and injuries and death from transport accidents caused by poor visibility. In addition, it may cause mental health affects due to stress (Perez et al., 2012;Ma et al., 2016;Middleton et al., 2008;Sprigg, 2016). In the Middle East (Iran, Iraq, Kuwait, and Saudi Arabia), hospital admissions can be high during dust events. ...
Article
Dust storms are an important environmental problem worldwide. The main sources of dust storms include the Sahara, the Middle East, and central and northeastern Asia. Dust originating from these regions can be dispersed across oceans and in some cases globally. The storms occur throughout the year and vary in frequency and intensity. The biological agents (e.g., fungi, bacteria and viruses) and the mineral and chemical compositions of dust may have adverse effects on human health and quality of life. Desert dusts may cause respiratory diseases, cardiovascular diseases, cardiopulmonary diseases, mental health issues, injuries and death from transport accidents caused by poor visibility. This paper presents dust storm human health research conducted in the Middle East in both indoor and outdoor environments. Results illustrate that particle concentration and bioaerosol types in the atmosphere are affected by climate change and meteorological factors. Recent data trends indicate that annual dust aerosol concentrations have increased worldwide. According to studies conducted in the Middle East, the incidence of respiratory and cardiovascular mortality and hospital visits have increased dramatically following dust storm exposures but very few have demonstrated a regional causation. National and international collaborative research is needed to advance our understanding of the global implications of dust storms and what may be the most effective means of mitigation.
... The proximate belief that Valley fever policy and atmospheric science are within reach of an operational warning and advisory system may be traced through three key publications: from a means to identify with greater confidence where Coccidioides thrive and how atmosphere/land models can forecast and simulate patterns of downwind risk ; an implementation strategy for a Global Dust Health Early Warning System (Sprigg, 2016); and the UNEP, et al. ...
Article
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The long journey of research to lower risks of Coccidioidomycosis (CM) began in the late 19 th century in Argentina and continued north to Mexico, the US and other countries. During this trip, medical science led the way. Although interdisciplinary research is not alien to medical science, e.g. geographic epidemiology, interaction with other disciplines has been low priority. This paper argues that the efficacy of CM mitigation and treatment can be improved through multi-and inter-disciplinary information exchange, particularly with earth and environmental sciences. Greater interaction and open publication practice are essential. Section 1 describes CM-epidemiology, the clinical features, the diagnosis and finally, the treatment. Section 2 discusses epidemiological evidence for atmospheric influence on cases of CM. Section 3 highlights the most important contributions and controversies in the history of CM-research through scientometric or bibliometric evaluations of research that are based on Garfield's work on the propagation of scientific thinking.
... The frequency and intensity of dust storms are increasing due to land-use and land-cover changes and climate-related factors (Section 2.4) particularly in some regions of the world such as the Arabian Peninsula (Jish Prakash et al. 2015;Yu et al. 2015;Gherboudj et al. 2017;Notaro et al. 2013;Yu et al. 2013;Alobaidi et al. 2017;Maghrabi et al. 2011;Almazroui et al. 2018) and broader Middle East (Rashki et al. 2012;Türkeş 2017;Namdari et al. 2018) as well as Central Asia (Indoitu et al. 2015;Xi and Sokolik 2015), with growing negative impacts on human health (high confidence) (Díaz et al. 2017;Goudarzi et al. 2017;Goudie 2014;Samoli et al. 2011). Dust storms transport particulate matter, pollutants, pathogens and potential allergens that are dangerous for human health over long distances (Goudie and Middleton 2006;Sprigg 2016). Particulate matter (PM; that is, the suspended particles in the air of up to 10 micrometres (PM10) or less in size), have damaging effects on human health (Díaz et al. 2017;Goudarzi et al. 2017;Goudie 2014;Samoli et al. 2011). ...
... Another direction is to control emissions, a contradiction in general belief that arid land dust emissions are a given, to be tolerated and impossible to mitigate.1-3-day forecasts of synoptic scale weather-driven airborne particulate matter plume trajectory, downwind concentration, and deposition: Several dust prediction methodologies, expressed in different model constructions, some combined, have shown promise over the Western U.S. for more than a decade (e.g.,Morain et al. 2010;Vukovic et al. 2014;Sprigg et al. 2014;Sprigg 2016;Tong et al. 2017). Arizona's Pima County Department of Environmental Quality posts PM2.5 daily model forecasts for public education and outreach (https://webcms.pima.gov/cms/One.aspx?portalId=169&pageId=689815 accessed 01/03/2022),provided by Tong's George Mason University research group. ...
... Small particles can penetrate into the lungs and cause adverse health effects via oxidative stress. Dust may contain heavy metals, organic compounds, and microorganisms and carry them to downwind areas, increasing respiratory, cardiovascular, cardiopulmonary, cancer, and mental diseases (Goudie 2014, Griffin et al. 2007, Ma et al. 2016, Middleton 2017, Perez et al. 2012, Sandstrom and Forsberg, 2008, Soleimani et al. 2020, Sprigg 2016. Airborne microorganisms (bio-aerosol) Communicated by Diane Purchase * Hossein Mohammad Asgari h.masgari@kmsu.ac.ir contain bacteria, fungi, viruses, protozoa, algae, and plant pollens (Lu et al. 2018;Maki et al. 2018). ...
Article
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Dust events impose negative socio-economic, health, and environmental impacts on vulnerable areas and reflect their sources’ physiochemical and biological characteristics. This study aimed to assess the impact of two dust sources on the concentration and diversity of airborne fungi in one of the dustiest areas in the world. This study is the first attempt to investigate the relationship between dust sources fungal community and those in airborne dust. Also, the contribution of dust sources to airborne fungi was estimated. Air masses arriving at the study area were assessed using local wind rose and the HYSPLIT model. Sampling was carried out from airborne dust at the Arvand Free Zone as target areas and soil in the dried parts of the Hor al-Azim and Shadegan wetlands as source areas to explore the relationship between fungi in the dust sources and the downwind area. The samples were analyzed in the lab to extract DNA. The internal transcribed spacer (ITS) regions of the rDNA gene were amplified using the primers ITS1F and ITS4, and then PCR products were sent to the lab for sequencing. The raw DNA data were processed using the QIIME virtual box to pick operational taxonomic units and taxonomy assignments. The most common fungi at the genus level were in the order of Penicillium > Aspergillus > Alternaria > Fusarium > Paradendryphiella > Talaromyces. The similarity between air and soil fungal genera was investigated using richness and diversity indices, the phylogenetic tree, and principal component analysis. The results showed that the community structures of ambient fungi in the Hor al-Azim and Shadegan dust sources were more similar to those on dusty days than non-dusty days. The source tracker model was used to quantify the contributions of known dust sources to airborne fungi. The results showed that the main source of airborne fungi was Hor al-Azim on dusty and non-dusty days. This study’s results can help managers identify and prioritize dust sources regarding fungal species.
... Dust emission is an important process that has an impact on climate (Boucher et al., 2013;Shao et al., 2011;Tegen et al., 1997), the global chemical flux (Lawrence & Neff, 2009;Mahowald et al., 2009), public health (Goudie, 2013;Sprigg, 2016), and the degradation of croplands (Bridges & Oldeman, 1999;Chappell et al., 2019;Chappell et al., 2012;Oldeman, 1992;Sterk et al., 1996;Visser & Sterk, 2007). Due to climate change, the emission of dust from disturbed soil surfaces from arid regions is expected to increase (Mahowald & Luo, 2003;Shepherd et al., 2016;Tegen et al., 2004;Woodward et al., 2005), which could enhance the on-and off-site effect of dust emission. ...
Article
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The Free State has been identified as the region with the most dust sources in South Africa. These dust sources can be linked with the large, heavily cultivated cropland areas in this province, which leaves fields vulnerable to wind erosion after the harvest in the winter. For this study, the focus was on the factors that influence the emission from bare, flat surfaces on agricultural lands in this region. The Portable In-Situ Wind Erosion Laboratory (PI-SWERL) was used to measure the emission flux from adjacent crusted and loose surfaces, which was combined with shear strength, moisture, and soil texture measurements. Boosted regression tree (BRT) analyses were used to identify the variable with the highest relevance on the emission flux. On the whole dataset, that the shear strength is the most important variable that controls the emission. This is reflected in the significantly lower emission from the crusted surfaces (0.49 mg m⁻² s⁻¹) compared to that of loose surfaces (2.34 mg m⁻² s⁻¹). However, for crusted surfaces, the presence of abraders appeared to be the most significant factor in emission, showing a power relationship between the abrader count and the emission flux (R² = 0.76). In the case of the loose surfaces, the presence of clay and silt was a major influence in emissivity, with a linear relationship between the two variables (R² = 0.68). This difference in factors depending on the agricultural disturbance, asks for a more holistic approach when predicting emission from such arid cropland areas.
... Mineral dust is one of the most abundant aerosol types in the atmosphere, playing a significant role in the climate system through influencing the Earth's radiation budget (i.e., absorbing and scattering terrestrial and solar radiation (Choobari et al. 2014), hydrological cycle (e.g., Karydis et al. 2017), carbon cycle (causing nutrient changes for ocean and terrestrial ecosystems, Jickells et al. 2005), soil organic carbon changes (Song et al. 2019;Du et al. 2021), and soil characteristics and geomorphology ). In addition to its significant impact on climate, dust storms also cause other effects on soil erosion (Nordstrom and Hotta 2004), health-related impacts (e.g., Griffin 2007;Sandstrom and Forsberg 2008;Goudie, 2014;Sprigg, 2016), satellite (Saleh and Abuhdima 2011) and railway (Cheng et al. 2015) communication problems, poor visibility conditions and its associated traffic accidents (Holyoak et al. 2011;Deetz et al. 2016), and water quality issues (Nativ et al. 1997). These effects not only occur in the dust source regions but also are observed in close vicinity or far from the source regions due to the long-distance transport of dust particles by strong wind circulations. ...
Article
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The Southeastern Anatolia Region (SEAR), the third-lowest mean annual precipitation region in Turkey, has semi-arid climate and plateau characteristics. The proximity of the region to North Africa and the Middle East dust source areas enables long-range transport of desert dust particles toward the SEAR by strong winds. Among the other dust source regions, the Arabian Peninsula has a crucial role in terms of affecting the SEAR with a high-annual frequency and high dust concentration values. We investigated the atmospheric patterns of three extreme Arabian dust episodes that affect the SEAR in this study. Dust episodes were determined using present weather (SYNOP) codes of ten stations in the SEAR during the 2014–2019 period. The source regions were found using HYSPLIT backward trajectory analysis. In this study, we benefited from synoptic maps, in situ PM10 observations, numerical simulations of the WRF-Chem model, and MODIS satellite images to analyze the extreme dust episodes. The results showed that the surface low pressure over the Persian Gulf and strong southerly winds at the 700-hPa level enabled the transport of dust particles from the surface to the mid-atmospheric levels. If the center of the upper-level ridge extended from Saudi Arabia to southern Turkey, the atmospheric blocking mechanism prevented the dispersion of dense dust particles from the SEAR to its surrounding, which caused the observation of high dust concentrations in the SEAR. In general, the WRF-Chem model outputs are in good agreement with ground-based PM10 concentrations and MODIS true-color images in terms of temporal and spatial distributions of dust concentrations.
... The emission of dust can have offsite effects on the regional and global climate [1][2][3], global geochemical fluxes [4,5], and human health [6,7]. For the emitting surface, dust emissions can lead to land degradation due to the removal of fine soil particles and organic material, especially in semi-arid and arid environments [8][9][10][11][12]. ...
Article
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The sandy croplands in the Free State have been identified as one of the main dust sources in South Africa. The aim of this study was to investigate the occurrence and strength of physical soil crusts on cropland soils in the Free State, to identify the rainfall required to form a stable crust, and to test their impact on dust emissions. Crust strength was measured using a fall cone penetrometer and a torvane, while laboratory rainfall simulations were used to form experimental crusts. Dust emissions were measured with a Portable In-Situ Wind Erosion Laboratory (PI-SWERL). The laboratory rainfall simulations showed that stable crusts could be formed by 15 mm of rainfall. The PI-SWERL experiments illustrated that the PM10 emission flux of such crusts is between 0.14% and 0.26% of that of a non-crusted Luvisol and Arenosol, respectively. The presence of abraders on the crust can increase the emissions up to 4% and 8% of the non-crusted dust flux. Overall, our study shows that crusts in the field are potentially strong enough to protect the soil surfaces against wind erosion during a phase of the cropping cycle when the soil surface is not protected by plants.
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This study investigates soil stabilization through two soil strengthening techniques, specifically; Bio-cementation through Microbial induced calcite precipitation (MICP) and Bio-polymerization using Xanthan gum for aeolian erosion control applications. The performances of these techniques were evaluated in terms of improvement in Threshold friction velocity (TFV), soil mass loss (%), and soil crust thickness formed with different levels of the treatment by conducting a series of experiments in the laboratory-scale wind tunnel and the microstructural observations with the help of FESEM and X-ray diffraction techniques. The results from wind erosion studies exhibited an improvement in TFV from 20 km/h for untreated to 45 km/h for MICP and biopolymer treated sand. A reduction in the soil mass loss from 75.23% for untreated to as least as 0% with both MICP and biopolymer treatment was observed. The results also indicated that the concentration of urea-cacl2 and biopolymer both played a critical role in soil improvement in both treatment methods. In MICP treated soil, the maximum wind speed of 45 km/h was encountered as TFV with 0.5M urea-cacl2. Whereas the TFV of biopolymer treated soil encountered the maximum wind speed of 45 km/h with a minimum of 0.25% of Xanthan Gum biopolymer solution.
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The risks associated with airborne soil particles (dust) are often underappreciated, and the gap between the knowledge pool and public awareness can be costly for society. This study reviews the emission, chemical, physical, and biological characteristics of dust and its effects on human and environmental health and safety in the Americas. American dust originates from both local sources and long-range transport from Africa and Asia. Dust properties, trends and interactions with criteria air pollutants are summarized. Human exposure to dust has been associated with adverse health effects, including asthma, fungal infections, and premature death. One of the most striking effects of dust is Coccidioidomycosis (Valley fever), an infection caused by inhaling soil-dwelling fungi unique to this region. Dust affects environmental health through providing nutrients to phytoplankton, contaminating water supply and food, spreading crop and marine pathogens, infecting domestic and wild animals, transporting heavy metals and radionuclides, and reducing solar power generation. Dust is also a well-documented safety hazard to road transportation, aviation, and marine navigation, in particular in the southwestern United States where blowing dust is one of the deadliest weather hazards. To mitigate these harmful effects, coordinated regional and international efforts are needed to enhance dust observations and prediction capabilities (especially in South America), implement soil conservation measures, design specific dust mitigation projects for transportation, and conduct surveillance for Valley fever and other diseases. While focusing on the Americas, many of the dust effects found in this region also exist in other parts of the world.
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This study aims to introduce alternative environmentally friendly compositions for soil-dust suppression. Carbon dioxide was utilized to produce free carbonate (CO32–) by a laboratory electrolysis cell. Different carbonate mineral compositions were then provided by adding Fe²⁺, Mg²⁺, and Ca²⁺ ions to the sodium carbonate solution. Different carbonate minerals were eventually used as soil stabilizing agents for sandy soil-dust suppression. Laboratory tests including unconfined compressive strength (UCS), direct shear test, California bearing ratio (CBR), and permeability tests in addition to field tests were performed to assess the feasibility of using CO2 induced carbonate minerals as soil stabilizing agent. It was found that the UCS and cohesion intercept of the treated specimens increased in comparison with the untreated specimens. CBR rating of the treated specimens indicated a harder surface which resulted in a lower permeability of the treated specimens. The study showed this alternative approach is a promising effort in utilization of CO2 for soil surface stability improvement.
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Convective dust storms, or haboobs, form when strong surface winds loft loose soils in convective storm outflow boundaries. Haboobs are a public safety hazard and can cause a near instantaneous loss of visibility, inimical air quality, and contribute significantly to regional dust and radiation budgets. Nevertheless, reliable predictions of convective dust events are inhibited by a lack of understanding regarding the complex and non-linear interactions between density currents, or convective cold pools, and dust radiative effects. In this study, the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) is utilized to simulate the effect dust radiation interactions have on a long-lived haboob case study that spans three distinct radiative regimes: day (high shortwave), evening (low shortwave), and night [longwave (LW) only]. A sophisticated algorithm is used to track and identify the numerous convective old pool boundaries in the simulations and assemble statistics that represent the impact of dust radiative effects. To first order, dust scattering of shortwave radiation in the day leads to a colder, dustier, and faster moving convective cold pool. In the transition period of early evening, the shortwave effects diminish while LW dust absorption leads to warmer, slower density currents that loft less dust as they propagate. At night, the haboob is again warmer due to dust absorption, but gustier in the more stable nocturnal surface layer, leading to enhanced dust emissions.
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Dust aerosols affect human life, ecosystems, atmospheric chemistry and climate in various aspects. Studies have revealed intensified dust activity in the western US during the past decades despite the weaker dust activity in non-US regions. It is important to extend the historical dust records, to better understand their temporal changes, and use such information to improve the daily dust forecasting skill as well as the projection of future dust activity under the changing climate. This study develops dust records in Arizona in 2005–2013 using multiple observation datasets, including in-situ measurements at the surface Air Quality System (AQS) and Interagency Monitoring of Protected Visual Environments (IMPROVE) sites, and level 2 deep blue aerosol product by the Moderate Resolution Imaging Spectroradiometer. The diurnal and inter-annual variability of identified dust events are shown related to observed weather patterns (e.g., wind and soil moisture) and vegetation conditions, suggesting a potential for use of satellite soil moisture and vegetation index products to interpret and predict dust activity. Back-trajectories computed using NOAA's Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) Model indicate that the Sonoran and Chihuahuan deserts are important dust source regions during identified dust events in Phoenix, Arizona. Finally, we evaluate the performance of the US National Air Quality Forecasting Capability (NAQFC) 12 km CMAQ model during a recent strong dust event in the western US accompanied by stratospheric ozone intrusion. It is shown that the current modeling system well captures the temporal variability and the magnitude of aerosol concentrations during this event, and the usefulness and limitations of different observations in model evaluation are discussed. Directions of integrating observations to further improve dust emission modeling in CMAQ are also suggested.
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A dust storm of fearful proportions hit Phoenix in the early evening hours of 5 July 2011. This storm, an American haboob, was predicted hours in advance because numerical, land–atmosphere modeling, computing power and remote sensing of dust events have improved greatly over the past decade. High-resolution numerical models are required for accurate simulation of the small scales of the haboob process, with high velocity surface winds produced by strong convection and severe downbursts. Dust productive areas in this region consist mainly of agricultural fields, with soil surfaces disturbed by plowing and tracks of land in the high Sonoran Desert laid barren by ongoing draught. Model simulation of the 5 July 2011 dust storm uses the coupled atmospheric-dust model NMME–DREAM (Non-hydrostatic Mesoscale Model on E grid, Janjic et al., 2001; Dust REgional Atmospheric Model, Nickovic et al., 2001; Pérez et al., 2006) with 4 km horizontal resolution. A mask of the potentially dust productive regions is obtained from the land cover and the normalized difference vegetation index (NDVI) data from the Moderate Resolution Imaging Spectroradiometer (MODIS). The scope of this paper is validation of the dust model performance, and not use of the model as a tool to investigate mechanisms related to the storm. Results demonstrate the potential technical capacity and availability of the relevant data to build an operational system for dust storm forecasting as a part of a warning system. Model results are compared with radar and other satellite-based images and surface meteorological and PM10 observations. The atmospheric model successfully hindcasted the position of the front in space and time, with about 1 h late arrival in Phoenix. The dust model predicted the rapid uptake of dust and high values of dust concentration in the ensuing storm. South of Phoenix, over the closest source regions (~25 km), the model PM10 surface dust concentration reached ~2500 μg m−3, but underestimated the values measured by the PM10 stations within the city. Model results are also validated by the MODIS aerosol optical depth (AOD), employing deep blue (DB) algorithms for aerosol loadings. Model validation included Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), equipped with the lidar instrument, to disclose the vertical structure of dust aerosols as well as aerosol subtypes. Promising results encourage further research and application of high-resolution modeling and satellite-based remote sensing to warn of approaching severe dust events and reduce risks for safety and health.
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The European Aerosol Research Lidar Network, EARLINET, was founded in 2000 as a research project for establishing a quantitative, comprehensive, and statistically significant database for the horizontal, vertical, and temporal distribution of aerosols on a continental scale. Since then EARLINET has continued to provide the most extensive collection of ground-based data for the aerosol vertical distribution over Europe. This paper gives an overview of the network's main developments since 2000 and introduces the dedicated EARLINET special issue, which reports on the present innovative and comprehensive technical solutions and scientific results related to the use of advanced lidar remote sensing techniques for the study of aerosol properties as developed within the network in the last 13 years. Since 2000, EARLINET has developed greatly in terms of number of stations and spatial distribution: from 17 stations in 10 countries in 2000 to 27 stations in 16 countries in 2013. EARLINET has developed greatly also in terms of technological advances with the spread of advanced multiwavelength Raman lidar stations in Europe. The developments for the quality assurance strategy, the optimization of instruments and data processing, and the dissemination of data have contributed to a significant improvement of the network towards a more sustainable observing system, with an increase in the observing capability and a reduction of operational costs. Consequently, EARLINET data have already been extensively used for many climatological studies, long-range transport events, Saharan dust outbreaks, plumes from volcanic eruptions, and for model evaluation and satellite data validation and integration. Future plans are aimed at continuous measurements and near-real-time data delivery in close cooperation with other ground-based networks, such as in the ACTRIS (Aerosols, Clouds, and Trace gases Research InfraStructure Network) www.actris.net, and with the modeling and satellite community, linking the research community with the operational world, with the aim of establishing of the atmospheric part of the European component of the integrated global observing system.
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Atmospheric mineral dust has recently become an important research field in Earth system science because of its impacts on radiation, clouds, atmospheric dynamics and chemistry, air quality, and biogeochemical cycles. Studying and modeling dust emission and transport over the world's largest source region, the Sahara, is particularly challenging because of the complex meteorology and a very sparse observational network. Recent advances in satellite retrievals together with ground-and aircraft-based field campaigns have fostered our understanding of the spatiotemporal variability of the dust aerosol and its atmospheric drivers. We now have a more complete picture of the key processes in the atmosphere associated with dust emission. These cover a range of scales from (1) synoptic scale cyclones in the northern sector of the Sahara, harmattan surges and African easterly waves, through (2) low-level jets and cold pools of mesoscale convective systems (particularly over the Sahel), to (3) microscale dust devils and dusty plumes, each with its own pronounced diurnal and seasonal characteristics. This paper summarizes recent progress on monitoring and analyzing the dust distribution over the Sahara and discusses implications for numerical modeling. Among the key challenges for the future are a better quantification of the relative importance of single processes and a more realistic representation of the effects of the smaller-scale meteorological features in dust models. In particular, moist convection has been recognized as a major limitation to our understanding because of the inability of satellites to observe dust under clouds and the difficulties of numerical models to capture convective organization.
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Light detection and ranging (LIDAR) can estimate daily volumes of sand dust particles from the East Asian desert to Japan. The objective of this study was to investigate the relationship between sand dust particles and pulmonary function, and respiratory symptoms in adult patients with asthma. One hundred thirty-seven patients were included in the study. From March 2013 to May 2013, the patients measured their morning peak expiratory flow (PEF) and kept daily lower respiratory symptom diaries. A linear mixed model was used to estimate the correlation of the median daily levels of sand dust particles, symptoms scores, and PEF. A heavy sand dust day was defined as an hourly concentration of sand dust particles of >0.1 km(-1). By this criterion, there were 8 heavy sand dust days during the study period. Elevated sand dust particles levels were significantly associated with the symptom score (0.04; 95% confidence interval (CI); 0.03, 0.05), and this increase persisted for 5 days. There was no significant association between PEF and heavy dust exposure (0.01 L/min; 95% CI, -0.62, 0.11). The present study found that sand dust particles were significantly associated with worsened lower respiratory tract symptoms in adult patients with asthma, but not with pulmonary function.
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In the framework of the World Meteorological Organisation's Sand and Dust Storm Warning Advisory and Assessment System, we evaluated the predictions of five state-of-the-art dust forecast models during an intense Saharan dust outbreak affecting Western and Northern Europe in April 2011. We assessed the capacity of the models to predict the evolution of the dust cloud with lead-times of up to 72 h using observations of aerosol optical depth (AOD) from the Aerosol Robotic Network (AERONET) and the Moderate Resolution Imaging Spectroradiometer (MODIS), and dust surface concentrations from a ground-based measurement network. In addition, the predicted vertical dust distribution was evaluated with vertical extinction profiles from the Cloud and Aerosol Lidar with Orthogonal Polarization (CALIOP). To assess the diversity in forecast capability among the models, the analysis was extended to wind field (both surface and profile), synoptic conditions, emissions and deposition fluxes. Models predict the onset and evolution of the AOD for all analysed lead-times. On average, differences among the models are larger than differences among lead-times for each individual model. In spite of large differences in emission and deposition, the models present comparable skill for AOD. In general, models are better in predicting AOD than near-surface dust concentration over the Iberian Peninsula. Models tend to underestimate the long-range transport towards Northern Europe. Our analysis suggests that this is partly due to difficulties in simulating the vertical distribution dust and horizontal wind. Differences in the size distribution and wet scavenging efficiency may also account for model diversity in long-range transport.
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Dust aerosols affect human life, ecosystems, atmospheric chemistry and climate in various aspects. Some studies have revealed intensified dust activity in the western US during the past decades despite the weaker dust activity in non-US regions. It is important to extend the historical dust records, to better understand their temporal changes, and to use such information to improve the daily dust forecasting skill as well as the projection of future dust activity under the changing climate. This study develops dust records in Arizona in 2005–2013 using multiple observation data sets, including in situ measurements at the surface Air Quality System (AQS) and Interagency Monitoring of Protected Visual Environments (IMPROVE) sites, and level 2 deep blue aerosol product by the Moderate Resolution Imaging Spectroradiometer. The diurnal and inter-annual variability of identified dust events are shown related to observed weather patterns (e.g., wind and soil moisture) and surface conditions (e.g., land cover type and vegetation conditions), suggesting a potential for use of satellite soil moisture and land products to help interpret and predict dust activity. Backtrajectories computed using NOAA's Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model indicate that the Sonoran and Chihuahuan deserts are important dust source regions during identified dust events in Phoenix, Arizona. Finally, we assess the impact of a recent strong dust event on western US air quality, using various observational and modeling data sets, during a period with a stratospheric ozone intrusion event. The capability of the current US National Air Quality Forecasting Capability (NAQFC) Community Multi-scale Air Quality (CMAQ) modeling system to represent the magnitude and the temporal variability of aerosol concentrations is evaluated for this event. Directions for integrating observations to further improve dust emission modeling in CMAQ are also suggested.
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Evidence on the association between short-term exposure to desert dust and health outcomes is controversial. To estimate the short-term effects of particulate matter ≤ 10 μm (PM10) on mortality and hospital admissions in 13 south-European cities, distinguishing between PM10 originating from desert and from other sources. We identified desert dust advection days in multiple Mediterranean areas for 2001-2010 by combining modelling tools, back-trajectories and satellite data. For each advection day, we estimated PM10 concentrations originating from desert, and computed PM10 from other sources by difference. We fitted city-specific Poisson regression models to estimate the association between PM from different sources (desert and non-desert) and daily mortality and emergency hospitalizations. Finally, we pooled city-specific results in a random-effects meta-analysis. On average, 15% of days were impacted by desert dust at ground level (desert PM10 > 0 μg/m(3)). Most episodes occurred in spring-summer, with increasing gradient of both frequency and intensity North-South and West-East of the Mediterranean basin. We found significant associations of both PM10 concentrations with mortality. Increases of 10-μg/m(3) in non-desert and desert PM10 (lag 0-1 days) were associated with increases in natural mortality of 0.55% (95% CI: 0.24, 0.87%) and 0.65% (95% CI: 0.24, 1.06%), respectively. Similar associations were estimated for cardio-respiratory mortality and hospital admissions. PM10 originated from desert was positively associated with mortality and hospitalizations in Southern Europe. Policy measures should aim at reducing population exposure to anthropogenic airborne particles even in areas with large contribution from desert dust advections.
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The objective of the study was to investigate the influence of Asian dust storms (ADS) on pulmonary function of school children and the relationship of this effect with interleukin-8. Morning peak expiratory flow (PEF) was measured daily in 399 children from April to May 2012 and in 384 of these children from March to May 2013. The data were analyzed for an association between ADS events and PEF by linear mixed models. Interleukin-8 transcriptional activity was assessed in THP-G8 cells stimulated by airborne particles collected on ADS days. Seven ADS days were identified: April 23 and 24, 2012; March 8 to 10, 2013; and March 19 and 20, 2013. Changes in PEF after ADS exposure were −8.17 L/min (95% confidence interval, −11.40 to −4.93) in 2012 and −1.17 L/min (−4.07 to 1.74) in 2013, and there was a significant difference between 2012 and 2013. Interleukin-8 transcriptional activity was significantly higher in 2012 at -fold compared to in March 8 to 10, 2013, and in March 19 and 20, 2013. The influence of ADS events on pulmonary function of children differs with each ADS event and may be related to interleukin-8 production.
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OBJECTIVE: Major sand storms are frequent in the Middle East. This study aims to investigate the role of air particulate matter (PM) level in acute asthma in children in Riyadh, Saudi Arabia. METHODS: An aerosol spectrometer was used to evaluate PM < 10μm in diameter (PM10) and PM < 2.5 μm in diameter (PM2.5) concentrations in the air every 30 minutes throughout February and March 2012 in Riyadh. Data on children 2-12 years of age presenting to the emergency department of a major children’s hospital with acute asthma during the same period were collected including their acute asthma severity score. RESULTS: The median with interquartile range (IQR) levels of PM10 and PM2.5 were 454 μg/m3 (309,864) and 108 μg/m3 (72,192) respectively. There was no correlation between the average daily PM10 levels and the average number of children presenting with acute asthma per day (r = –0.14, P = 0.45), their daily asthma score (r = 0.014, P = 0.94), or admission rate ( r= –0.08, P = 0.65). This was also true for average daily PM2.5 levels. In addition, there was no difference in these variables between days with PM10 >1000 μg/m3, representing major sand storms, plus the following 5 days and other days with PM10 < 1000 μg/m3. CONCLUSION: Sand storms, even major ones, had no significant impact on acute asthma exacerbations in children in Riyadh, Saudi Arabia. The very high levels of PM, however, deserve further studying especially of their long-term effects.
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We used real-time polymerase chain reaction and culture to demonstrate persistent colonization of soils by Coccidioides immitis, an agent of valley fever, in Washington State linked to recent human infections and located outside the endemic range. Whole-genome sequencing confirmed genetic identity between isolates from soil and one of the case-patients.
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Fine particulate matter is one of the most important factors contributing to air pollution. Epidemiological studies have related increased levels of atmospheric particulate matter to premature human mortality caused by cardiopulmonary disease and lung cancer. However, a limited number of investigations have focused on the contribution of airborne desert dust particles. Here we assess the effects of dust particles with an aerodynamic diameter smaller than 2.5 μm (DU2.5) on human mortality for the year 2005. We used the EMAC atmospheric-chemistry general circulation model at high resolution to simulate global atmospheric dust concentrations. We applied a health impact function to estimate premature mortality for the global population of 30 yr and older, using parameters from epidemiological studies. We estimate a global cardiopulmonary mortality of about 402 000 in 2005. The associated years of life lost are about 3.47 million per year. We estimate the global fraction of the cardiopulmonary deaths caused by atmospheric desert dust to be about 1.8%, though in the 20 countries most affected by dust this is much higher, about 15-50%. These countries are primarily found in the so-called "dust belt" from North Africa across the Middle East and South Asia to East Asia
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Human saliva is clinically informative of both oral and general health. Since next generation shotgun sequencing (NGS) is now widely used to identify and quantify bacteria, we investigated the bacterial flora of saliva microbiomes of two healthy volunteers and five datasets from the Human Microbiome Project, along with a control dataset containing short NGS reads from bacterial species representative of the bacterial flora of human saliva. GENIUS, a system designed to identify and quantify bacterial species using unassembled short NGS reads was used to identify the bacterial species comprising the microbiomes of the saliva samples and datasets. Results, achieved within minutes and at greater than 90% accuracy, showed more than 175 bacterial species comprised the bacterial flora of human saliva, including bacteria known to be commensal human flora but also Haemophilus influenzae, Neisseria meningitidis, Streptococcus pneumoniae, and Gamma proteobacteria. Basic Local Alignment Search Tool (BLASTn) analysis in parallel, reported ca. five times more species than those actually comprising the in silico sample. Both GENIUSand BLAST analyses of saliva samples identified major genera comprising the bacterial flora of saliva, but GENIUS provided a more precise description of species composition, identifying to strain in most cases and delivered results at least 10,000 times faster. Therefore, GENIUS offers a facile and accurate system for identification and quantification of bacterial species and/or strains in metagenomic samples.
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On 5 July 2011, a massive dust storm struck Phoenix, Arizona (USA), raising concerns for increased cases of valley fever (coccidioidomycosis, or, cocci). A quasi-operational experimental airborne dust forecast system predicted the event and provides model output for continuing analysis in collaboration with public health and air quality communities. An objective of this collaboration was to see if a signal in cases of valley fever in the region could be detected and traced to the storm – an American haboob. To better understand the atmospheric life cycle of cocci spores, the DREAM dust model (also herein, NMME-DREAM) was modified to simulate spore emission, transport and deposition. Inexact knowledge of where cocci-causing fungus grows, the low resolution of cocci surveillance and an overall active period for significant dust events complicate analysis of the effect of the 5 July 2011 storm. In the larger context of monthly to annual disease surveillance, valley fever statistics, when compared against PM10 observation networks and modeled airborne dust concentrations, may reveal a likely cause and effect. Details provided by models and satellites fill time and space voids in conventional approaches to air quality and disease surveillance, leading to land–atmosphere modeling and remote sensing that clearly mark a path to advance valley fever epidemiology, surveillance and risk avoidance.
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Abstract As a result of the challenge of recent dust storms to public health, we tested the postulate that desert dust collected in the southwestern United States imparts a biological effect in respiratory epithelial cells and an animal model. Two samples of surface sediment were collected from separate dust sources in northeastern Arizona. Analysis of the PM20 fraction demonstrated that the majority of both dust samples were quartz and clay minerals (total SiO2 of 52 and 57%). Using respiratory epithelial and monocytic cell lines, the two desert dusts increased oxidant generation, measured by Amplex Red fluorescence, along with carbon black (a control particle), silica, and NIST 1649 (an ambient air pollution particle). Cell oxidant generation was greatest following exposures to silica and the desert dusts. Similarly, changes in RNA for superoxide dismutase-1, heme oxygenase-1, and cyclooxygenase-2 were also greatest after silica and the desert dusts supporting an oxidative stress after cell exposure. Silica, desert dusts, and the ambient air pollution particle NIST 1649 demonstrated a capacity to activate the p38 and ERK1/2 pathways and release pro-inflammatory mediators. Mice, instilled with the same particles, showed the greatest lavage concentrations of pro-inflammatory mediators, neutrophils, and lung injury following silica and desert dusts. We conclude that, comparable to other particles, desert dusts have a capacity to (1) influence oxidative stress and release of pro-inflammatory mediators in respiratory epithelial cells and (2) provoke an inflammatory injury in the lower respiratory tract of an animal model. The biological effects of desert dusts approximated those of silica.
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The European Aerosol Research Lidar Network, EARLINET was founded in 2000 as a research project for establishing a quantitative, comprehensive and statistically significant database for the horizontal, vertical, and temporal distribution of aerosols on a continental scale. Since then EARLINET is continuing to provide the most extensive collection of ground-based data for the aerosol vertical distribution over Europe. This paper gives an overview of the network's main developments since 2000 and introduces the dedicated EARLINET special issue which reports on the present innovative and comprehensive technical solutions and scientific results related to the use of advanced lidar remote sensing techniques for the study of aerosol properties as developed within the network in the last thirteen years. Since 2000, EARLINET has strongly developed in terms of number of stations and spatial distribution, from 17 stations in 10 countries in 2000, to 27 stations in 16 countries in 2013. EARLINET has strongly developed also in terms of technological advances with the spread of advanced multi-wavelength Raman lidar stations in Europe. The developments for the quality assurance strategy, the optimization of instruments and data processing and dissemination of data have contributed to a significant improvement of the network towards a more sustainable observing system, with an increase of the observing capability and a reduction of operational costs. Consequently, EARLINET data have already been extensively used for many climatological studies, long-range transport events, Saharan dust outbreaks, plumes from volcanic eruptions and for model evaluation and satellite data validation and integration. Future plans are in the direction of continuous measurements and near real time data delivery in close cooperation with other ground-based networks, as in the ACTRIS research infrastructure, and with the modelling and satellite community, bridging the research community with the operational world towards the establishment of the atmospheric part of the European component of the integrated global observing system.
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Background: Epidemics of meningococcal meningitis are concentrated in sub-Saharan Africa during the dry season, a period when the region is affected by the Harmattan, a dry and dusty northeasterly trade wind blowing from the Sahara into the Gulf of Guinea. Objectives: We examined the potential of climate-based statistical forecasting models to predict seasonal incidence of meningitis in Niger at both the national and district levels. Data and methods: We used time series of meningitis incidence from 1986 through 2006 for 38 districts in Niger. We tested models based on data that would be readily available in an operational framework, such as climate and dust, population, and the incidence of early cases before the onset of the meningitis season in January–May. Incidence was used as a proxy for immunological state, susceptibility, and carriage in the population. We compared a range of negative binomial generalized linear models fitted to the meningitis data. Results: At the national level, a model using early incidence in December and averaged November–December zonal wind provided the best fit (pseudo-R2 = 0.57), with zonal wind having the greatest impact. A model with surface dust concentration as a predictive variable performed indistinguishably well. At the district level, the best spatiotemporal model included zonal wind, dust concentration, early incidence in December, and population density (pseudo-R2 = 0.41). Conclusions: We showed that wind and dust information and incidence in the early dry season predict part of the year-to-year variability of the seasonal incidence of meningitis at both national and district levels in Niger. Models of this form could provide an early-season alert that wind, dust, and other conditions are potentially conducive to an epidemic.
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Simulations of climate, including atmospheric chemistry and carbon cycle, are conducted for the period from 1850 through 2100 with a new earth system model (ESM) of the Meteorological Research Institute (MRI), MRI-ESM1. This model has been developed as an extension of the atmosphere-ocean coupled general circulation model, MRI-CGCM3, by adding chemical and biogeochemical processes. The dynamic and thermodynamic processes are entirely the same in both models. The horizontal resolution of MRI-ESM1 is higher than that of the ozone model that handles chemical processes which require high computational cost. In the control experiment, it is confirmed that the climatic drift of the model is insignificant with regard to surface air temperature (SAT), the radiation budget, and trace gas (carbon dioxide (CO2) and ozone) concentrations. Compared with a control experiment by MRI-CGCM3, SAT is slightly higher because of a higher tropospheric ozone concentration. The performance of MRI-ESM1 is validated by conducting a historical experiment. Overall, MRI-ESM1 simulates well observed historical changes in SAT and trace gas concentrations. However, increases in the SAT and atmospheric CO2 concentration are underestimated, associated with a positive feedback process through soil respiration. Namely the underestimation of atmospheric CO2 increase causes weak SAT rise which makes soil respiration inactive, and then the excess of net land surface CO2 uptake suppresses increase of the atmospheric CO2 concentration. The simulated present-day climate states of SAT, radiation fluxes, precipitation, and trace gas concentrations are also in good agreement with observations although there are errors of radiations, precipitation, and ozone concentration especially over the southern tropical Pacific in the simulation. These errors appear to be originated from the excess of convective activity: so-called double ITCZ (intertropical convergence zone). Both MRI-ESM1 and MRI-CGCM3 are similarly able to reproduce the present-day climatology. In future projections, the global mean SAT rise at the end of the 21st century relative to the pre-industrial era is 3.4°C in the experiment using the Representative Concentration Pathways 8.5 (RCP8.5) by MRI-ESM1, whereas it is 4.0°C in the MRI-CGCM3 experiment. The atmospheric CO2 concentration projected by MRI-ESM1 for the end of the 21st century is about 800 ppm, which is lower by 130 ppm than that prescribed in the RCP8.5 experiment with MRI-CGCM3. This difference is consistent with the above-mentioned difference in the SAT rise between MRI-ESM1 and MRI-CGCM3. The global mean total column ozone increases by about 25 DU during the period from 2000 to 2100, which is comparable to that prescribed in the experiment with MRI-CGCM3. It is also investigated how aerosols simulated with a newly introduced aerosol-chemistry process influence weak SAT rise at the end of the 20th century in MRI-ESM1.
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A technique is presented to produce real-time, daily vegetation composites at 0.01$^{circ}$ resolution $({sim}{rm 1}~{rm km})$ over the Conterminous United States (CONUS) for use in the NASA Land Information System (LIS) and weather prediction models. Green vegetation fraction (GVF) is derived from direct-broadcast swaths of normalized difference vegetation index from the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the NASA Earth Observing System satellites. The real-time data and increased resolution compared to the 0.144$^{circ}$$({sim}{rm 16}~{rm km})$ resolution monthly GVF climatology in community models result in an improved representation of vegetation in high-resolution models, especially in complex terrain. The MODIS GVF fields show seasonal variations that are similar to the community model climatology, and respond realistically to temperature and precipitation anomalies. The wet spring and summer 2010 over the U.S. Plains led to higher regional GVF than in the climatology. The GVF substantially decreased over the U.S. Southern Plains from 2010 to 2011, consistent with the transition to extreme drought in summer 2011. LIS simulations depict substantial sensitivity to the MODIS GVF, with regional changes in heat fluxes around 100 ${rm Wm}^{-2}$ over the northern U.S. in June 2010. CONUS LIS simulations during the 2010 warm season indicate that the larger MODIS GVF in the western U.S. led to higher latent heat fluxes and initially lower sensible heat fluxes, with a net drying effect on the soil. With time, the drier soil eventually lead to higher mean sensible heat fluxes such that the total surface energy- output increased by late summer 2010 over the western U.S. A sensitivity simulation of a severe weather event using real-time MODIS GVF data results in systematic changes to low-level temperature, moisture, and instability fields, and improves the evolution of simulated precipitation.
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Every year huge quantities of soil dust are carried by winds from Africa, across the Atlantic, and to the Caribbean. No other ocean region is so extensively and persistently impacted by such high concentrations of dust, a region that extends over 7000 km from the coast of Africa to the Caribbean and to the bounding continental shores of the Americas. In effect, the Caribbean Basin can be thought of as the receptor site of the Saharan dust source, a source that accounts for over half of global dust emissions. It is generally recognized that on a global scale mineral dust can affect many aspects of climate, marine biogeochemical processes, soil fertility, air quality, and human health. However, it is difficult to assess the impact on the Caribbean Basin because of the dearth of studies in this region. A better understanding is needed of the factors that affect the transport of dust, the physical and chemical properties of the transported materials, and how these might change during transport. Of particular interest is how climate change might affect dust transport in the future. Presented here is a brief overview of research relevant to the region and issues in dust-related research that need to be addressed.
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The level 2 aerosol bacicscatter and extinction profiles from the NASA Micropulse Lidar Network (MPLNET) at Kanpur, India, have been studied from May 2009 to September 2010. Monthly averaged extinction profiles from MPLNET shows high extinction values near the surface during October March. Higher extinction values at altitudes of 2-4 km are observed from April to June, a period marked by frequent dust episodes. Version 3 level 2 Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) aerosol profile products have been compared with corresponding data from MPLNET over Kanpur for the above-mentioned period. Out of the available back-scatter profiles, the16 profiles used in this study have time differences less than 3 h and distances less than 130 km. Among these profiles, four cases show good comparison above 400 m with R-2 greater than 0.7. Comparison with AERONET data shows that the aerosol type is properly identified by the CALIOP algorithm. Cloud contamination is a possible source of error in the remaining cases of poor comparison. Another source of error is the improper backscatter-to-extinction ratio, which further affects the accuracy of extinction coefficient retrieval.
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Dust storms and associated mineral aerosol transport are driven primarily by meso- and synoptic-scale atmospheric processes. It is therefore essential that the dust aerosol process and background atmospheric conditions that drive dust emissions and atmospheric transport are represented with sufficiently well-resolved spatial and temporal features. The effects of airborne dust interactions with the environment determine the mineral composition of dust particles. The fractions of various minerals in aerosol are determined by the mineral composition of arid soils; therefore, a high-resolution specification of the mineral and physical properties of dust sources is needed. Several current dust atmospheric models simulate and predict the evolution of dust concentrations; however, in most cases, these models do not consider the fractions of minerals in the dust. The accumulated knowledge about the impacts of the mineral composition in dust on weather and climate processes emphasizes the importance of including minerals in modeling systems. Accordingly, in this study, we developed a global dataset consisting of the mineral composition of the current potentially dust-producing soils. In our study, we (a) mapped mineral data to a high-resolution 30 s grid, (b) included several mineral-carrying soil types in dust-productive regions that were not considered in previous studies, and (c) included phosphorus.
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The Nile Delta major cities, particularly Cairo, experienced stagnant air pollution episodes, known as Black Cloud, every year over the past decade during autumn. Low-elevated thermal inversion layers play a crucial role in intensifying pollution impacts. Carbon monoxide, ozone, atmospheric temperature, water vapor, and methane measurements from the tropospheric emission spectrometer (TES) on board the Aura have been used to assess the dominant component below the inversion layer. In this study, time series analysis, autocorrelations, and cross correlations are performed to gain a better understanding of the connections between those parameters and their local effect. Satellite-based data were obtained for the years 2005–2010. The parameters mentioned were investigated throughout the whole year in order to study the possible episodes that take place in addition to their change from year to year. Ozone and carbon monoxide were the two major indicators to the most basic episodes that occur over Cairo and the Delta region.
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The vitality of Caribbean coral reefs has undergone a continual state of decline since the late 1970s, a period of time coincidental with large increases in transatlantic dust transport. It is proposed that the hundreds of millions of tons/year of soil dust that have been crossing the Atlantic during the last 25 years could be a significant contributor to coral reef decline and may be affecting other ecosystems. Benchmark events, such as near synchronous Caribbean-wide mortalities of acroporid corals and the urchin Diadema in 1983, and coral bleaching beginning in 1987, correlate with the years of maximum dust flux into the Caribbean. Besides crustal elements, in particular Fe, Si, and aluminosilicate clays, the dust can serve as a substrate for numerous species of viable spores, especially the soil fungus Aspergillus. Aspergillus sydowii, the cause of an ongoing Caribbean-wide seafan disease, has been cultured from Caribbean air samples and used to inoculate sea fans.
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Inclusion of mineral dust radiative effects could lead to a significant improvement in the radiation balance of numerical weather prediction models with subsequent improvements in the weather forecast itself. In this study the radiative effects of mineral dust have been fully incorporated into a regional atmospheric dust model. Dust affects the radiative fluxes at the surface and the top of the atmosphere and the temperature profiles at every model time step when the radiation module is processed. These changes influence the atmospheric dynamics, moisture physics, and near-surface conditions. Furthermore, dust emission is modified by changes in friction velocity and turbulent exchange coefficients; dust turbulent mixing, transport, and deposition are altered by changes in atmospheric stability, precipitation conditions, and free-atmosphere winds. A major dust outbreak with dust optical depths reaching 3.5 at 550 nm over the Mediterranean region on April 2002 is selected to assess the radiative dust effects on the atmosphere at a regional level. A strong dust negative feedback upon dust emission (35–45% reduction of the AOD) resulted from the smaller outgoing sensible turbulent heat flux decreasing the turbulent momentum transfer from the atmosphere and consequently dust emission. Significant improvements of the atmospheric temperature and mean sea-level pressure forecasts are obtained over dust-affected areas by considerably reducing both warm and cold temperature biases existing in the model without dust-radiation interactions. This study demonstrates that the use of the proposed model with integrated dust and atmospheric radiation represents a promising approach for further improvements in numerical weather prediction practice and radiative impact assessment over dust-affected areas.
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We have developed a dust aerosol module integrated into a global aerosol transport model, called MASINGAR (Model of Aerosol Species IN the Global AtmospheRe). The dust module treats dust-emission processes based on the saltation-bombardment theory. A global soil texture database is used to determine the size distribution of parent soils. Erodibility factors for vegetation cover, snow cover, land-use type, and soil type are considered. Dry and wet deposition processes are dependent on particle size. To obtain a climatological global dust emission, deposition, and spatial distribution, we performed a 25-year simulation which is assimilated to the 1979-2003 condition, using a nudging scheme. The simulated annual mean global emission flux and atmospheric dust load (with 0.2 ≤ D ≤ 20 μm) are 2149 (1817-2339) Tg yr−1 and 17.9 (15.6-20.4) Tg. The surface concentrations and depositions are compared with observed data, and the dust emission flux is compared with previous model studies. The model reproduces the simulated seasonal variation of dust concentration at stations near East Asian dust sources, where most previous models have underestimated the amounts and amplitudes. The global simulation results indicate that the quantitative estimation of the dust budget is sensitive to the size distribution of the emitted dust.
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SUMMARY Coccidioidomycosis is the endemic mycosis caused by the fungal pathogens Coccidioides immitis and C. posadasii. This review is a summary of the recent advances that have been made in the understanding of this pathogen, including its mycology, genetics, and niche in the environment. Updates on the epidemiology of the organism emphasize that it is a continuing, significant problem in areas of endemicity. For a variety of reasons, the number of reported coccidioidal infections has increased dramatically over the past decade. While continual improvements in the fields of organ transplantation and management of autoimmune disorders and patients with HIV have led to dilemmas with concurrent infection with coccidioidomycosis, they have also led to advances in the understanding of the human immune response to infection. There have been some advances in therapeutics with the increased use of newer azoles. Lastly, there is an overview of the ongoing search for a preventative vaccine.
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An integrated modeling system has been developed to accurately describe the dust cycle in the atmosphere. It is based on the SKIRON/Eta modeling system and the Eta/NCEP regional atmospheric model. The dust modules of the entire system incorporate the state of the art parameterizations of all the major phases of the atmospheric dust life such as production, diffusion, advection, and removal. These modules also include effects of the particle size distribution on aerosol dispersion. The dust production mechanism is based on the viscous/turbulent mixing, shear-free convection diffusion, and soil moisture. In addition to these sophisticated mechanisms, very high resolution databases, including elevation, soil properties, and vegetation cover are utilized. The entire system is easily configurable and transferable to any place on the Earth, it can cover domains on almost any size, and its horizontal resolution can vary from about 100 km up to approximately 4 km. It can run on one-way-nested form if necessary. The performance of the system has been tested for various dust storm episodes, in various places and resolution using gridded analysis or forecasting fields from various sources (ECMWF and NCEP) for initial and boundary conditions. The system is in operational use during the last two years, providing 72 hour forecasts for the Mediterranean region. The results are available on the internet (http://www.icod.org.mt and http://forecast.uoa.gr).
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An extraordinarily severe yellow sand event was observed in Korea for the period of 21-23 March 2002. This event has been simulated using the three-dimensional eulerian transport model with meteorological outputs of the Regional Data Assimilation and Prediction System (RDAPS) together with the statistically derived dust emission conditions from WMO 3 hourly synoptic reporting data for seven spring seasons (March-May) from 1996 to 2002 in East Asia. The statistically derived dust-rise conditions with the help of the Chinese soil map in the source regions are found to be the threshold wind speed of 9.5, 7.5, 6.0 and 9.2 m s-1 and the upper limit of relative humidity of 60, 35, 30% and 40% in the Gobi, Sand, Loess and Mixed soil regions, respectively. These dust-rise conditions are implemented to the eulerian long-range transport model to simulate the extraordinarily intensive yellow sand event observed in Korea in terms of temporal and spatial variations of dust concentrations, starting and ending times of the yellow sand event over the Korean peninsula. It is found that the model simulates quite well the observed concentrations of more than 1,000 mug m-3 within the same order of magnitude and the starting and ending times of yellow sand in Korea within an hour. The spatial distribution of vertically integrated dust concentration in the model is quite well coincided with that of aerosol index obtained by total ozone mapping spectrometer (TOMS). The simulated dust particle sizes indicate that most of mass concentrations of dust in the source regions are mainly contributed by dust particles larger than PM10 whereas those at distant regions from the sources are largely attributed to the PM10 particles, suggesting the usefulness of the particle size spectrum in identifying the origin of a dust storm. The presently derived emission conditions enable to forecast the yellow sand event in Korea more reasonably than previously used conditions of threshold friction velocities.
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NASA Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) Version 3.01 5-km nighttime 0.532 mu m aerosol optical depth (AOD) datasets from 2007 are screened, averaged and evaluated at 1 degrees x 1 degrees resolution versus corresponding/co-incident 0.550 mu m AOD derived using the US Navy Aerosol Analysis and Prediction System (NAAPS), featuring two-dimensional variational assimilation of quality-assured NASA Moderate Resolution Imaging Spectroradiometer (MODIS) and Multi-angle Imaging Spectroradiometer (MISR) AOD. In the absence of sunlight, since passive radiometric AOD retrievals rely overwhelmingly on scattered radiances, the model represents one of the few practical global estimates available from which to attempt such a validation. Daytime comparisons, though, provide useful context. Regional-mean CALIOP vertical profiles of night/day 0.532 mu m extinction coefficient are compared with 0.523/0.532 mu m ground-based lidar measurements to investigate representativeness and diurnal variability. In this analysis, mean nighttime CALIOP AOD are mostly lower than daytime (0.121 vs. 0.126 for all aggregated data points, and 0.099 vs. 0.102 when averaged globally per normalised 1 degrees x 1 degrees bin), though the relationship is reversed over land and coastal regions when the data are averaged per normalised bin (0.134/0.108 vs. 0140/0.112, respectively). Offsets assessed within single bins alone approach +/- 20 %. CALIOP AOD, both day and night, are higher than NAAPS over land (0.137 vs. 0.124) and equal over water (0.082 vs. 0.083) when averaged globally per normalised bin. However, for all data points inclusive, NAAPS exceeds CALIOP over land, coast and ocean, both day and night. Again, differences assessed within single bins approach 50% in extreme cases. Correlation between CALIOP and NAAPS AOD is comparable during both day and night. Higher correlation is found nearest the equator, both as a function of sample size and relative signal magnitudes inherent at these latitudes. Root mean square deviation between CALIOP and NAAPS varies between 0.1 and 0.3 globally during both day/night. Averaging of CALIOP along-track AOD data points within a single NAAPS grid bin improves correlation and RMSD, though day/night and land/ocean biases persist and are believed systematic. Vertical profiles of extinction coefficient derived in the Caribbean compare well with ground-based lidar observations, though potentially anomalous selection of a priori lidar ratios for CALIOP retrievals is likely inducing some discrepancies. Mean effective aerosol layer top heights are stable between day and night, indicating consistent layer-identification diurnally, which is noteworthy considering the potential limiting effects of ambient solar noise during day.
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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.
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