Non-dusty Days Research Articles

Combined impact of heat and dust on diabetes hospitalization in Kuwait

IntroductionIn Kuwait, a severe diabetes and obesity epidemic coexists with intense dust storms and harsh summer heat. While, theoretically, this interplay between dust, heat, and diabetes presents a serious public...

Short-term and long-term effects of exposure to PM10

IntroductionA dust storm is a harmful event in the environment and human health resulting from certain chemicals in the air that transcend predefined levels. Developing countries, such as Iran, suffer from this basic threat (dust particles) to health. The purpose of the research was to evaluate the effects of PM10 particulate matter on mortality related to cardiovascular diseases (CVD) in the year 2022–2023 in Andimeshk City, with the AirQ + programmed. Material and methodThe recommended approach for evaluating effects on health, as recognized by the world health organization (WHO), uses the Air Quality Health Impact Assessment Software (Air Q 2.2.3). The polluted air information required for model runs was obtained from the Environmental Department of Khuzestan. The Khuzestan Meteorological Organization gave information on the levels of particulate matter for both dusty and non-dusty days. The mortality numbers came from the Iranian Statistics Centre and the Health Ministry. The data was collected in a volumetric manner for the year 2022–2023. ResultThe lowest PM10 concentration reported in a year in Andimeshk city belonged to January 9 (14.19 μg/m3), while the most polluted day of the year was November 6 (5634.61 μg/m3). The total monthly concentration of PM10 for April, May, June, July, August, September, October, November, December, January, and February respectively, 2917.9, 3227.82, 3175.89, 2966.24, 3520.46, 3393.1, 4671.07, 13121.26, 3042.63, 1851.67, 2627.52, and 6758.12 μg/m3. ConclusionThe results of this study showed that the studied area is a polluted city in terms of the concentration of dust particles. So, during a year, only 8 days, PM10 concentration did not exceed the standard. One of the main reasons for air pollution in Andimshek city is the neighborhood of Khuzestan province with Iraq and Saudi Arabia, which have dry areas and dust storms.

Seasonal variability of airborne mold concentrations as related to dust in a coastal urban area in the Eastern Mediterranean.

Recent studies have demonstrated that the amount of specific airborne mold types and their concentrations increase during dust events. This study investigates the seasonal variation of airborne mold concentrations before, during, and after the dust transport in an eastern Mediterranean coastal area, Izmir city, Turkey. A total of 136 airborne mold samples were collected between September 2020 and May 2021. Two different culture media, namely Potato Dextrose Agar (PDA) and Malt-Extract Agar (MEA), were used for enumeration and genus-based identification of the airborne mold. In addition to culture media, the influences of air temperature, relative humidity, and particulate matter equal to or less than 10µm (PM10) were also investigated seasonally. The HYSPLIT trajectory model and web-based simulation results were mainly used to determine dusty days. The mean total mold concentrations (TMC) on dusty days (543 Colony Forming Unit (CFU)/m3 on PDA and 668CFU/m3 on MEA) were approximately 2-2.5 times higher than those on non-dusty days (288CFU/m3 on PDA and 254CFU/m3 on MEA) for both culture media. TMC levels showed seasonal variations (p < 0.001), indicating that meteorological parameters influenced mold concentrations and compositions. Some mold genera, including Cladosporium sp., Chrysosporium sp., Aspergillus sp., Bipolaris sp., Alternaria sp., and yeast, were found higher during dusty days than non-dusty days. Thus, dust event impacts levels and types of airborne molds and has implications for regions where long-range dust transport widely occurs.

Effect of dusty weather on the performance of the PV/Trombe wall: Experimental assessment

The current article studies the effect of dusty weather conditions on the performance of PV/Trombe wall Photovoltaic. Two experimental models were built to study the impact of climatic changes and operating conditions on the PV/Trombe wall, one with DC fans and the other without DC fans. The operating conditions for dusty and non-dusty days were tested to show their impact on system efficiency. In the case of the model using DC fans on a clear day, the electrical and thermic efficiency of the model reached 10.2% and 17.6%, respectively. While in the case of the model without DC fans and on a clear day, the electrical and thermic efficiency of the model reached 8.4% and 40.1%, respectively. In the case of the model using DC fans on a dusty day, the electrical and thermic efficiency of the model reached 6.6% and 11.9%, respectively. While in the case of the model without DC fans and on a dusty day, the electrical and thermic efficiency of the model reached 3.5% and 34.1%, respectively. Dusty weather conditions reduce the electrical efficiency of the PV/TW system; the average daily electrical efficiency increase was 2.4% under clear weather conditions compared to dusty weather conditions. Also, the dusty weather conditions lead to an apparent decrease in the temperatures of the solar panel and air in the room. The decrease was 12% compared to a clear day.

Status of TNF-α and IL-6 as pro-inflammatory cytokines in exhaled breath condensate of late adolescents with asthma and healthy in the dust storm and non-dust storm conditions.

Exposure to airborne particulate matter (PM) can be considered as an important risk factor for human health. Some cytokines have been recognized as the biomarkers of exposure to air pollution. Experimental studies indicate that PM exposure could be associated with inflammation. Thus, the purpose of this study was to evaluate whether the exposure to air PM is associated with biomarkers of inflammation. The specific aim of this study was to determine the correlation between airborne PM levels and IL-6 and TNF-α as airway inflammation biomarkers among two groups of late adolescents in northwest of Iran. This study included 46 subjects, comprising 23 asthmatic subjects and 23 non-asthmatic persons. Environmental PM (PM10, PM2.5 and PM1) levels were measured in dust storm and non-dust storm days during both cold and warm seasons. Following the sampling of PM, Two pro-inflammatory cytokines of IL-6 and TNF-α in exhaled breath condensate (EBC) were also determined in the EBC samples via commercial ELISA kits. Daily mean ambient air PM10, PM2.5 and PM1 concentrations during the dust storm days was 221.79, 93.13 and 25.52 μg m-3 and in non-dusty days 48.37, 18.54 and 6.1 μg m-3, respectively. Biomarkers levels were significantly (p < 0.001) higher in asthmatic students compared to the non-asthmatic subjects. EBC cytokines levels were increased in dust storm days compared to the non-dusty days (p < 0.001) and were positively correlated with different size of ambient PM concentration. Dust storm conditions can increase the pro-inflammatory cytokines and cause adverse effects on pulmonary health and lung tissue damage.

The Relationship Between Dust Sources and Airborne Bacteria in the Southwest of Iran.

The biological agents are carried from deserts and dried lands to long distances by high dust volumes. Their adverse effects can be reduced by specifying and controlling dust sources and their related biological agents. Thus, the current work examined the relationship between the bacteria in air and soil samples by taking samples from the soil surface of two dust sources, as well as from air samples during spring from Khorramshahr and Abadan cities. The dust event is the most influential factor on airborne bacteria. There is an insignificant negative (-0.06), insignificant positive (0.14), and weak positive (0.24) correlation between airborne bacteria and UV radiation, relative humidity, and temperature, respectively. After preparing a 16S ribosomal DNA (rDNA) clone library from the soil and air samples, operational taxonomic unit picking and taxonomic assignment were conducted using QIIME Virtual Box. In the present work, Bacillus was the dominant species. The relationship between dust sources and air samples was determined by principal component analysis. Bacteria in the Hoor-Al-Azim dust source and airborne bacteria on dusty and non-dusty days showed a more significant correlation compared to bacteria in the Shadegan dust source. Source Tracker software was used to estimate the contribution of dust sources. The primary source of dust was associated with the dried areas of Hoor-Al-Azim on the non-dusty and dusty days. Finally, the long transport of airborne bacteria was assessed by moderate resolution imaging spectroradiometer (MODIS) and the back trajectory model of Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) data. The research findings can help decision-makers prioritize dust sources to control the adverse effects of dust.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11356-022-21563-6.

Health Effects of Dust Storms on the South Edge of the Taklimakan Desert, China: A Survey-Based Approach.

Dust storms have already become the most serious environmental problem on the south edge of the Taklimakan desert because of their frequent occurrences. To investigate the health effects of dust storms on public health in Moyu County, one of the most severe dust-storm-affected areas located at the south edge of the Taklimakan desert, China, primary data were collected from 1200 respondents by using a questionnaire survey for 15 health symptoms. The data were analyzed by comparing the mean tool (independent t-test and ANOVA) and the severity of different symptoms among different age groups. Principal component analysis (PCA) was applied to further analyze the multivariate relationships between meteorological factors, dust storm intensity, air pollution level, and severity degree of the different symptoms. The results show that significant correlations exist between dust storm intensity, air pollutants (PM2.5, PM10, O3, SO2, NO2, and CO), meteorological factors, and health symptoms. During dusty weather, no matter the age group, the number of respondents who suffered from different health symptoms was higher compared to non-dusty days. Three types of dusty days were considered in this study: suspended dust, blowing dust, and sand storms. The impacts of sand storm weather on public health are stronger than those from blowing dust weather, suspended dust weather (haze), and non-dust weather. The people in the age groups above 60 years and below 15 years were more sensitive to different dust weather than people in the age groups between 15 and 60. “Dry throat with bitter taste”, “Depression”, “Dry and itchy throat”, and “Mouth ulcer” are the main symptoms caused by dust storms.

Assessing the relationship between airborne fungi and potential dust sources using a combined approach.

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.

Quantification of long-range transported aeolian dust towards the Indian peninsular region using satellite and ground-based data - A case study during a dust storm over the Arabian Sea

The Arabian Sea is an enclosed basin surrounded by land and is prone to receive large amount of aeolian dust from the continent. This can significantly impact surface water biogeochemical processes. In this study, an attempt has been made to quantify the amount of dust transported from Middle East region to Indian subcontinent (sampling site is Goa; 15.45°N 73.80°E; located in the northeast Arabian Sea) via the Arabian Sea. We identified a dust storm episode (02–10 April 2015) in the Arabian Peninsula and its propagation to the study site (Goa) using satellite data (MODIS and CALIPSO). The impact of the dust storm at Goa has been computed using ambient particulate matter concentration and satellite retrieved optical parameter. These observations were further substantiated using ground-based micro-pulse lidar measurement. The daily averaged lidar profile shows relatively high depolarization ratio (0.1–0.25), as well as high daily average backscatter coefficient (up to 0.08 Sr−1 Km−1) and extinction coefficient (up to 0.9 Km−1) during the storm period compared to non-dusty days. During this period, a two-layer (rich in non-spherical particle) structure with significantly high linear depolarization ratio is observed, indicating the impact of the dust storm at the coastal region of India. Ambient mass concentration of dust estimated using CALIPSO profile are comparable with the gravimetric mass measured from high volume sample collection. The back-trajectory analysis further supports the advection of air-mass from the Middle East to Eastern Arabian Sea. This study highlight the significant role of long-range transport in impacting dust load at the remote/receptor sites.

Particulate matters and bioaerosols during Middle East dust storms events in Ilam, Iran

Particulate matters can be transferred distances from their sources. Due to different chemical and microbial characteristics, they can potentially impact on public health and ecosystems. Therefore, in this study we aimed to study the concentrations of particulate matters (PM2.5 and PM10) and types of bacteria in the ambient air of Ilam city during dusty (PM10 ≥ 150 µg/m3) and non-dusty days from February 2012 to February 2013. Totally, there existed more dust storm events during warm and dry months. The Mann-Whitney test confirmed a significant relationship between dusty and non-dusty days (P < 0.05). Totally, by increasing the PM concentrations, the number of bacterial colonies increased. Kruskal-Wallis test showed that there was a significant relationship between the number of bacterial colonies and season. The mostly observed bacterial colonies were Staphylococcus, Cryptococcus, Corynebacterium, Bacillus, Actinosynnema, Nocardioides, Arthrobacter, Flavimonas, Paenibacillus, Pseudomonas, Microbacterium, Planococcus, Streptomyces, Kurthia, Neisseria Agrococcus, Curtobacterium, Duganella, Ancylobacter, Paracoccus, Propionibacterium, Pseudomonas, Rhizobium and Enterococci. The predominant direction of dust plumes in Ilam city was from the west of Ilam from neighboring countries. The higher number of microbial colonies during dusty days in this city obviously showed the important role of these events on microbial characteristics.

PM10 levels at urban, suburban, and background locations in the eastern Mediterranean: local versus regional sources with emphasis on African dust

PM10 levels were determined at different locations in a coastal site in the eastern Mediterranean to assess the relative contribution of local versus regional sources. Two campaigns were conducted: during the first, PM10 was monitored at three urban locations (kerbside/traffic/background) at different sampling periods, whereas during the second one, PM10 was simultaneously measured at two locations (urban/suburban). Both campaigns have shown that African dust transport was a major carrier of coarse particles. Daily PM10 concentrations of 547 μg m−3 and 234 μg m−3 were measured during the first and the second campaigns, respectively, both of them associated with severe dust storms. However, some dust episodes influenced lesser PM10 levels. The contribution from dust episodes to the measured concentration was estimated at 2–527 μg m−3 during the first campaign and 4–218 μg m−3 during the second campaign. Classification into dusty and non-dusty days has shown that local anthropogenic sources also influence ambient PM10 concentrations; however, few exceedances of the daily limit of 50 μg m−3 occurred during both campaigns. Particularly, it was found that domestic heating during cold months was a major contributor to PM10 levels followed by emissions from traffic with higher contribution of the latter during summer months (high touristic season) as well as non-traffic emissions (road dust resuspension). Hourly average PM10 concentration during the second campaign has shown that traffic-related emissions and/or road dust resuspension were associated with up to 40 μg m−3 whereas during wintertime late evening hours, PM10 concentration from heating reached up to 60 μg m−3 at the central urban location.

Short-term effects of ambient air pollution and cardiovascular events in Shiraz, Iran, 2009 to 2015.

Air pollution and dust storms are associated with increased cardiovascular hospital admissions. The aim of this study was to investigate the association between short-term exposure to ambient air pollutants and CVD (cardiovascular disease) events in a long-term observational period. The study included the events of cardiovascular diseases (namely coronary artery disease, ischemic heart disease, myocardial infarction, and pneumo thrombo embolism) within the population of Shiraz, from March 21, 2009 to March 20, 2015. Also, each patient's demographics were recorded. Main meteorological variables and five ambient pollutants (CO, O3, SO2, NO2, and PM10) were recorded. Statistical analysis was performed using linear regression (GLM) and a generalized additive model (GAM) estimating Poisson distribution and adjusted for the main risk factors and ambient meteorological variables. A mild prevalence (51.5%) of coronary artery disease (CAD) was registered in 6425 events. In GLM analysis, we observed an association among the pollutants with the coronary artery disease hospital admissions which was in the order of CO, NO2, and PM10. The highest association of each pollutant with hospital admission was observed as PM10 at lag 4 (RR = 1.08; 95% CI 1.02, 1.14 and p < 0.05), NO2 at lag 0 (RR = 1.22; 95% CI 1.00, 1.48), and CO at lag 0 (RR = 1.52 95% CI = (1.16, 1.99)). However, on dusty days, there were significantly higher numbers of referrals of cardiovascular patients (mean = 7.54 ± 4.44 and p = 0.002,) than on non-dusty days. According to these data, dust storms and some types of pollutants in the air are responsible for more admissions to hospitals for cardiovascular problems.

Aerosol and Meteorological Parameters Associated with the Intense Dust Event of 15 April 2015 over Beijing, China

The northeastern parts of China, including Beijing city, the capital of China, were hit by an intense dust storm on 15 April 2015. The present paper discusses aerosol and meteorological parameters associated with this dust storm event. The back trajectory clearly shows that the dust originated from Inner Mongolia, the border of China, and Mongolia regions. Pronounced changes in aerosol and meteorological parameters along the dust track were observed. High aerosol optical depth (AOD) with low Ångström exponent (AE) are characteristics of coarse-mode dominated dust particles in the wavelength range 440–870 nm during the dusty day. During dust storm, dominance of coarse aerosol concentrations is observed in the aerosol size distribution (ASD). The single scattering albedo (SSA) retrieved from AERONET station shows increase with higher wavelength on the dusty day, and is found to be higher compared to the days prior to and after the dust event, supported with high values of the real part and decrease in the imaginary part of the refractive index (RI). With regard to meteorological parameters, during the dusty day, CO volume mixing ratio (COVMR) is observed to decrease, from the surface up to mid-altitude, compared with the non-dusty days due to strong winds. O3 volume mixing ratio (O3VMR) enhances at the increasing altitudes (at the low-pressure levels), and decreases near the surface at the pressure levels 500–925 hPa during the dust event, compared with the non-dusty periods. An increase in the H2O mass mixing ratio (H2OMMR) is observed during dusty periods at the higher altitudes equivalent to the pressure levels 500 and 700 hPa. The mid-altitude relative humidity (RH) is observed to decrease at the pressure levels 700 and 925 hPa during sand storm days. With the onset of the dust storm event, the RH reduces at the surface level.

Investigation of optical and radiative properties of aerosols during an intense dust storm: A regional climate modeling approach

The dynamical and optical properties of aerosols during an intense dust storm event over the Arabian Sea have been studied using Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) and space borne instruments such as MODIS, MISR, CALIPSO and CERES during the period 17 to 24 March, 2012. The model captures the spatio-temporal and vertical variations of meteorological and optical parameters, however an overestimation in simulated aerosol optical parameters are observed when compared to satellite retrievals. The correlation coefficients (R) between simulated and observed AOD from MODIS and MISR are found to be 0.54 and 0.32 respectively. Model simulated AOD on dusty days (20 and 21 March 2012) increased by 2–3 times compared to non-dusty days (17 and 24 March 2012) and the single scattering albedo (SSA) and the asymmetry parameter increased from 0.96 to 0.99 and from 0.56 to 0.66, respectively. The R between simulated shortwave (SW) radiation at top of the atmosphere (TOA) and TOA SW radiation obtained from CERES is found to be 0.43, however the model simulated SW radiation at the TOA showed an underestimation with respect to CERES. The shortwave aerosol radiative forcing (SWARF) during the event over surface and TOA are ∼ -19.3 and ∼ -14.2 Wm-2 respectively, which is about 2–5 times higher when compared to the respective forcing values during non-dust days. Estimated net radiative forcing was in the range of −13 to −21 Wm-2 at TOA and −12 to −20 Wm-2 at the surface. The heating rate during event days within the lower atmosphere near 850 hPa is found to 0.32 − 0.4 K day−1 and 0.18 − 0.22 K day−1 on dusty and non-dusty days, respectively. Results of this study may be useful for a better modeling of atmospheric aerosols and its optical and radiative properties over oceanic region.

Effect of Dust Storms on the Atmospheric Microbiome in the Eastern Mediterranean.

We evaluated the impact of Saharan dust storms on the local airborne microbiome in a city in the Eastern Mediterranean area. Samples of particles with diameter less than 10 μm were collected during two spring seasons on both dusty and nondusty days. DNA was extracted, and partial 16S rRNA gene amplicons were sequenced using the Illumina platform. Bioinformatic analysis showed the effect of dust events on the diversity of the atmospheric microbiome. The relative abundance of desert soil-associated bacteria increased during dust events, while the relative abundance of anthropogenic-influenced taxa decreased. Quantitative polymerase chain reaction measurements of selected clinically significant antibiotic resistance genes (ARGs) showed that their relative abundance decreased during dust events. The ARG profiles on dust-free days were similar to those in aerosol collected in a poultry house, suggesting a strong agricultural influence on the local ambient profiles. We conclude that dust storms enrich the ambient airborne microbiome with new soil-derived bacteria that disappear as the dust settles, suggesting that the bacteria are transported attached to the dust particles. Dust storms do not seem to be an important vector for transport of probed ARGs.

The Signature of Aerosols and Meteorology in Long-Term Cloud Radar Observations of Trade Wind Cumuli

Abstract The signature of aerosols and meteorology on the development of precipitation from shallow cumuli in the trades is investigated with ground-based lidar and radar remote sensing. The measurements are taken from a cloud observatory recently established on the windward shore of Barbados. Cloud microphysical development is explored through an analysis of the radar echo of shallow cumuli before the development of active precipitation. The increase of reflectivity with height (Z gradient) depends on the amount of cloud water, which varies with meteorology, and cloud droplet number concentration N, which varies with the aerosol. Clouds with a large Z gradient have a higher tendency to form precipitation than clouds with a small Z gradient. Under similar meteorological conditions, the Z gradient is expected to be large in an environment with few aerosols and small in an environment with many aerosols. The aerosol environment is defined using three methods, but only one (based on the Raman lidar linear-depolarization ratio) to measure dusty conditions correlates significantly with the Z gradient. On average, nondusty days are characterized by a larger Z gradient. However, the dust concentration varies seasonally and covaries with relative humidity. Large-eddy simulations show that small changes in the relative humidity can have as much influence on the development of precipitation within the cloud layer as large changes in N. When clouds are conditioned on their ambient relative humidity, the sensitivity of the Z gradient to dust vanishes.

Determination of the Concentration and Composition of PM10 during the Middle Eastern Dust Storms in Sanandaj, Iran.

The present study investigated the effect of the Middle East dust storm episodes on the concentration and composition of PM10 during April to September 2013 in Sanandaj City, western Iran. Sampling was once every six days, and on dusty days using an Omni air sampler. The PM10 sample was collected on polytetrafluoroethylene filters. Average of 24 h values of PM10 mass concentrations was determined. Half of each sample filter and blank filter was analyzed for water -soluble ions and the other half was digested for metal analysis. The average PM10 concentration was 160.63 μg/m3. The lowest and highest concentrations of PM10 were in May and June respectively. The average PM10 concentration during the non-dusty days was 96.88 (μg /m3). Nevertheless, it increased by 4.8 times during the dusty days. Ca2+, Cl-, NO3-, and Na+ accounted for 71% of total water-soluble ions on the dusty days. During the dusty days, the dominant elements in PM10 were Na, Ca, Mg, Al, and Fe contributing to 95.72% of total measured metals. The correlation coefficient and enrichment factor analysis have shown that on dusty days, Al, Ca, Fe, K, Mg, Na, Sr, and V were the elements with the crustal sources. Concentrations of PM10 during dusty days were considerably higher than that during non-dusty days. In addition, concentrations of water-soluble ions and metals were also higher during dusty days.

Comparative analysis of chemical composition and sources of aerosol particles in urban Beijing during clear, hazy, and dusty days using single particle aerosol mass spectrometry

A single particle aerosol mass spectrometer (SPAMS) was employed to characterize the particles in urban Beijing in the spring of 2011. The whole sampling time was divided into clear, hazy, and dusty day periods. Based on SPAMS results, the chemical composition of size-resolved particles in five major classes, including K-rich, carbonaceous, industry metal, dust, and Na-rich particles, and their corresponding sources were compared during clear, hazy, and dusty days. Air mass back trajectories are used to identify likely source regions for each period. Under stagnant meteorological conditions, local and regional emissions are a key factor in haze formation. K-rich and carbonaceous particles dominated under all conditions (25–54%), with higher contributions (23% and 29%) from industrial metal particles during hazy days, which could be attributed to the emission of biomass burning, coal combustion, and vehicle exhaust during all periods, whereas industrial metal processes are also a likely source for K-rich particles during hazy days. The aging of particles was observed over the whole sampling period, as evidenced by the presence of secondary species in all particle classes. Industrial metal particles possibly originate from industrial metal processes, vehicle exhaust, and coal combustion etc, while road and soil dust is also a possible source during dusty days. Dust particles increased greatly (17%) in a dust storm event with a coarse mode distribution, which are mainly associated with the mineral dust from deserted regions, whereas they could originate from local dust and coal combustion during non-dusty days. Last, Na-rich particles are mainly associated with industrial metal particles, coal, and fuel combustion during hazy days, and mineral dust during dusty days, respectively. Sea salt is a possible source of Na-rich particles under all conditions. Our analysis could shed a light on the understanding of the different source apportionment of aerosol particles under different meteorology/pollution conditions.

Composite analysis of impacts of dust aerosols on surface atmospheric variables and energy budgets in a semiarid region of China

Loess Plateau is one of the dust aerosol source regions featured by its sandy underlying surface and affected significantly by dust events. In order to investigate climatic forcing of dust aerosols in semiarid region, continuous observations of particulate matter (PM10 concentration), meteorological elements, and energy fluxes were collected at Semiarid Climate Observatory and Laboratory in northwestern China from March to May during 2007–2010. The result shows that dusty days are often evoked under the condition when a strengthening trough is combined with the development of strong convection. During dusty days, the frequency of northerly winds increases significantly with the average wind velocity to be around 4.0 m/s; temperature is low during the daytime and high at nighttime. Relative humidity and surface pressure, however, are about 15% and 70% lower than average in dusty days, respectively. Energy balance closure is typically poor in dusty days. During daytime, the downward/upward solar radiation at land surface is less in dusty days than in nondusty days with the largest difference of 206.7 W/m2 and 33.25 W/m2, respectively. Difference in downward longwave radiation between dusty and nondusty days is 35 W/m2, accounting for 11.7% and 14% of the daily mean for dusty and nondusty days, respectively. The net radiation flux, as well as sensible/latent heat fluxes at surface is smaller during the daytime but larger at nighttime in dusty days. The maximum differences of sensible/latent heat fluxes between dusty and nondusty days can reach for 41.9% and 12.1% of the maximum net radiation, respectively.

Changes in aerosol optical properties due to dust storms in the Middle East and Southwest Asia

Super dust storms occurred over the Middle East and southwest Asia on March 2012. These storms reduced the air quality over the Gulf Region, Iraq, Iran, and Pakistan. Airports were shut down due to poor visibility, schools were closed, and hundreds of people were hospitalized with respiratory problems. In order to better understand the effects of such dust storms we have analyzed aerosol optical and radiative properties during this event using data from the Moderate Resolution Imaging Spectroradiometer and the Aerosol Robotic Network. Maximum aerosol optical depth (AOD) values occurred on the18th of March in Kuwait, Bahrain, Qatar, and Saudi Arabia, where values of 4.9, 4.4, 4.3, and 4.9 were recorded, respectively. In Oman, the Arabian Sea, and Iran, maximum AOD values occurred on the 19th of March, reaching 4.5, 5, and 5, respectively. The dust storm then spread across Pakistan, passing through Multan, Faisalabad, and Lahore where maximum AOD values of 2.1, 2.6, and 2.7, respectively, were attained on the 20th of March. The maximum aerosol volume size distributions (VSDs) in Lahore occurred on dusty days and minimum VSDs on non-dusty days. The VSD, single scattering albedo, refractive index, and asymmetry parameter values on dusty days suggested that dust aerosols were predominant over anthropogenic aerosols in these urban environments. The shortwave aerosol radiative forcing (ARF) values (on both dusty and non-dusty days) ranged between −50Wm−2 and −194Wm−2 (average: −114±40Wm−2) at the earth's surface, and between −31Wm−2 and −105Wm−2 (average: −58±25Wm−2) at the top of the atmosphere (TOA). The longwave aerosol ARF values ranged between +6Wm−2 and +20Wm−2 (average: +12±4Wm−2) at the earth's surface, and between +7Wm−2 and +30Wm−2 (average: +16±7Wm−2) at the TOA. Longwave radiations therefore produced significant warming, both at the TOA and at the earth's surface.