High-volume Cascade Impactor Research Articles

Review on Sampling Methods and Health Impacts of Fine (PM2.5, ≤2.5 µm) and Ultrafine (UFP, PM0.1, ≤0.1 µm) Particles

Airborne particulate matter (PM) is of great concern in the modern-day atmosphere owing to its association with a variety of health impacts, such as respiratory and cardiovascular diseases. Of the various size fractions of PM, it is the finer fractions that are most harmful to health, in particular ultrafine particles (PM0.1; UFPs), with an aerodynamic diameter ≤ 100 nm. The smaller size fractions, of ≤2.5 µm (PM2.5; fine particles) and ≤0.1 µm (PM0.1; ultrafine particles), have been shown to have numerous linkages to negative health effects; however, their collection/sampling remains challenging. This review paper employed a comprehensive literature review methodology; 200 studies were evaluated based on the rigor of their methodologies, including the validity of experimental designs, data collection methods, and statistical analyses. Studies with robust methodologies were prioritised for inclusion. This review paper critically assesses the health risks associated with fine and ultrafine particles, highlighting vehicular emissions as the most significant source of particulate-related health effects. While coal combustion, diesel exhaust, household wood combustors’ emissions, and Earth’s crust dust also pose health risks, evidence suggests that exposure to particulates from vehicular emissions has the greatest impact on human health due to their widespread distribution and contribution to air pollution-related diseases. This article comprehensively examines current sampling technologies, specifically focusing on the collection and sampling of ultrafine particles (UFP) from ambient air to facilitate toxicological and physiochemical characterisation efforts. This article discusses diverse approaches to collect fine and ultrafine particulates, along with experimental endeavours to assess ultrafine particle concentrations across various microenvironments. Following meticulous evaluation of sampling techniques, high-volume air samplers such as the Chem Vol Model 2400 High Volume Cascade Impactor and low-volume samplers like the Personal Cascade Impactor Sampler (PCIS) emerge as effective methods. These techniques offer advantages in particle size fractionation, collection efficiency, and adaptability to different sampling environments, positioning them as valuable tools for precise characterisation of particulate matter in air quality research and environmental monitoring.

Black carbon and PM0.49 characterization in manila north harbour port, Metro Manila, Philippines

Globalization and industrialization have increased the shipping activities in Metro Manila. This increase in economic activity has contributed to the exacerbation of atmospheric particle pollution, particularly black carbon (BC) and particulate matter (PM). In this study, PM0.49 and BC were characterized in North Harbour in Metro Manila, Philippines. Using a multiple-split high-volume cascade impactor, PM0.49 and PM2.5 were collected from December 2019 to January 2020. Equivalent BC (eBC) mass concentrations were measured using an aethalometer (AE33, Magee Scientific) while chemical analysis was also performed using ion chromatography. The PM0.49 was tested for its morphological and mineralogical characteristics. Daily analysis showed no significant difference between the weekday and weekend pollution concentration in the port, although mean concentration (70 ± 21 μg/m3) exceeds that of the 24-hr Philippine air quality guideline value of 50 μg/m3 for PM2.5 concentrations. The particle compositions of PM0.49 are mostly from Si-rich particles and Pb-rich particles. High variability was observed for Mg, Si, Ca, Fe, Cd, Zn, Mn, S, Cl, V, and Cr heavy metals. The carbonaceous species with the highest concentration was organic carbon (OC) (33 ± 9 μg/m3) followed by BC (16 ± 3 μg/m3) and eBC (12 ± 3 μg/m3). An analysis of the ionic species showed SOX and NOX emissions as the primary ions, which are mostly related to ship emissions while the mineralogical analysis showed that soot particles are the main composition of the particles. Overall, the pollution assessment showed that North Harbour is polluted with heavy metals but within the Philippine air quality pollutant standard. In brief, the results of this study suggest that atmospheric pollution in the study site was mostly caused by local anthropogenic sources, particularly vessel emissions. The researchers suggest that a longer study period be conducted to further assess the seasonal variation of atmospheric particle pollution in North Harbour, Metro Manila.

Impact of weather on the behaviour of Alternaria spore and Alt a 1 concentration in the air of Ankara (Turkey)

Intact fungal spores and smaller fungal fragments such as hyphae are sources of airborne allergens. Information on the distribution of sub-spore allergenic particles in the atmosphere is however limited. Therefore, the main aim of this study was to explore the behaviour of Alternaria aeroallergens in the atmosphere of Ankara, central Turkey. Aerobiological monitoring was carried out in the 2020 season. A Burkard volumetric spore trap was used for fungal spore collection, and a high-volume cascade impactor for allergen collection. The Alt a 1 levels in two air fractions (particulate matter (PM) > 10 µm and 10 > PM > 2.5 µm) were measured by an enzyme-linked immunosorbent assay. The seasonal spore integral (SSIn) was 1846 spore day/m3. In the same period, a total of 95.71 pg/m3 Alt a 1 concentration was recorded, of which 93% was recorded in PM>10 and 7% in PM10–2.5 air fraction. The amount of allergen per spore was 5.18 × 10−2 pg/spore/m3. The highest concentration for both spores and allergens was observed on 30 June, i.e. before the local crop harvest. Four days with highest spore levels occurred about one week after the rainfall (> 1 mm). Hot and humid weather probably contributed to the intensive development of fungi and an increase in the concentration of spores in the atmosphere. Our findings suggest that in areas with semi-arid climate, such as central Turkey, the weather conditions have a greater effect on behaviour of the distribution of Alternaria aeroallergens than agricultural practices.

Road tunnel-derived coarse, fine and ultrafine particulate matter: physical and chemical characterization and pro-inflammatory responses in human bronchial epithelial cells

BackgroundTraffic particulate matter (PM) comprises a mixture of particles from fuel combustion and wear of road pavement, tires and brakes. In countries with low winter temperatures the relative contribution of mineral-rich PM from road abrasion may be especially high due to use of studded tires during winter season. The aim of the present study was to sample and characterize size-fractioned PM from two road tunnels paved with different stone materials in the asphalt, and to compare the pro-inflammatory potential of these fractions in human bronchial epithelial cells (HBEC3-KT) in relation to physicochemical characteristics.MethodsThe road tunnel PM was collected with a vacuum pump and a high-volume cascade impactor sampler. PM was sampled during winter, both during humid and dry road surface conditions, and before and after cleaning the tunnels. Samples were analysed for hydrodynamic size distribution, content of elemental carbon (EC), organic carbon (OC) and endotoxin, and the capacity for acellular generation of reactive oxygen species. Cytotoxicity and pro-inflammatory responses were assessed in HBEC3-KT cells after exposure to coarse (2.5–10 μm), fine (0.18–2.5 μm) and ultrafine PM (≤ 0.18 μm), as well as particles from the respective stone materials used in the pavement.ResultsThe pro-inflammatory potency of the PM samples varied between road tunnels and size fractions, but showed more marked responses than for the stone materials used in asphalt of the respective tunnels. In particular, fine samples showed significant increases as low as 25 µg/mL (2.6 µg/cm2) and were more potent than coarse samples, while ultrafine samples showed more variable responses between tunnels, sampling conditions and endpoints. The most marked responses were observed for fine PM sampled during humid road surface conditions. Linear correlation analysis showed that particle-induced cytokine responses were correlated to OC levels, while no correlations were observed for other PM characteristics.ConclusionsThe pro-inflammatory potential of fine road tunnel PM sampled during winter season was high compared to coarse PM. The differences between the PM-induced cytokine responses were not related to stone materials in the asphalt. However, the ratio of OC to total PM mass was associated with the pro-inflammatory potential.

Daily Variation of Air Pollutants Near an Elevated Highway System

I-81 is an elevated viaduct and goes through the heart of Syracuse, with local businesses and communities located underneath it. The safety limit of the viaduct is ending, and the NY Department of Transportation (DOT) is looking for recommendations to rebuild the roadway using its current elevated design or lower the highway to ground level creating a community grid. People living below I-81 are concerned about increases in air pollution if I-81 is lowered. With no knowledge of current air quality levels in this community, assessing how lowering the highway would impact the neighborhood is impossible. We began an air quality monitoring campaign to measure pollutant levels simultaneously near the highway and on the ground below. Models generated by the DOT suggest traffic levels will not change if the highway is lowered. By monitoring air quality at highway and ground levels, results will offer a glimpse of potential air quality problems that could arise. To assess daily variation in traffic-related particulate matter (PM) near this highway, a site adjacent to I-81 was selected. Two high-volume cascade impactors were placed at ground and highway levels of a building to collect daily PM samples for two weeks over two seasons. Two real-time PM monitors measured PM number concentration with elevation. For fine PM at the rooftop location, the average number of particles was 1.2 times higher with a maximum of 10 times higher. Three days in summer had exceptionally high vehicle flow and had PM concentrations ranging from 4.5 to 10 times higher at highway level. Results from gravimetric analyses agreed with measured number concentrations. This data shows particle count and PM concentration are variable with elevation and suggests that vehicle emissions may be more influential at highway level, implying air quality may be affected if the community grid option is pursued.

Seasonal Evolution of Size-Segregated Particulate Mercury in the Atmospheric Aerosol Over Terra Nova Bay, Antarctica.

Size-fractionated particulate mercury (PHg) measurements were performed from November 2017 to January 2018 at Terra Nova Bay (Antarctica) for the first time. Samples were collected every 10 days by a six-stage high-volume cascade impactor with size classes between 10 μm and 0.49 μm. Total PHg concentrations were maxima (87 ± 8 pg m−3) in November, then decreased to values ~40% lower and remained almost constant until the end of the sampling period (~30 pg m−3). The trimodal aerosol mass distribution reveals that from 30% to 90% of the total PHg came in the size > 1.0 μm. Hg in the two coarse fractions was probably produced by the adsorption of oxidized Hg species transported by air masses from the Antarctic plateau or produced locally by sea ice edges. PHg in accumulation mode seemed to be related to gas–particle partitioning with sea salt aerosol. Finally, average dry deposition fluxes of PHg were calculated to be 0.36 ± 0.21 ng m−2 d−1 in the accumulation mode, 47 ± 44 ng m−2 d−1 in the first coarse mode, and 37 ± 31 ng m−2 d−1 in the second coarse mode. The present work contributed to the comprehension of the Hg biogeochemical cycle, but further research studies are needed.

Black carbon and size-segregated elemental carbon, organic carbon compositions in a megacity: a case study for Istanbul

In this study, black carbon (BC), particulate matter (PM), nitrogen oxides (NOx), and sulphur dioxide (SO2) were monitored between May 2019 and February 2020. During this sampling period, size-segregated particle samples were collected by a high-volume cascade impactor, once a week. Elemental carbon (EC) and organic carbon (OC) were investigated on the size-segregated particles. The study was carried out at Esenler district of Istanbul. Main sources in the vicinity of the sampling area are Central Coach Station of Istanbul, residential buildings, small-scale industrial facilities, and O-1 and O-2 highway connection. The average BC concentration was 2763 ± 1974 ng/m3. PM10 and PM2.5 concentrations were 38.2 ± 17.4 and 21.5 ± 12.4 μg/m3, respectively. BC comprised 12.8% and 7.2% of PM2.5 and PM10, respectively. Diurnal variation of BC had a similar trend with NO2 concentrations, which showed peak concentrations during rush hours. BC had high Pearson correlation coefficients with NO, NO2, and PM2.5. The geographical position of possible emission sources was estimated through conditional probability function. The Central Coach Station of Istanbul had the highest geographical possibility for BC sources. EC and OC exhibited bimodal size distribution. The coarse mode peak was at 0.95–1.5-μm size bin for OC, whilst it was at 1.5–3-μm size bin for EC. Since EC and BC exhibit the same origin with different measurement principles, we concluded that resuspension of road dust also contributed ambient BC concentrations.

Organic chemical characterization of size segregated particulate matter samples collected from a thermal power plant area

Kütahya city, a thermal power plant (TPPs) affected region of Turkey, has serious air quality problems like similar industrial regions of the world due to the emissions from three closely-located coal-fired TPPs, residential coal combustion along with the contribution of several industrial stacks. The organic chemical speciation of ambient size-segregated particulate matter (PM) was investigated during two seasons at two sites with different pollution characteristics (urban and rural). The ambient PM was collected using a high volume cascade impactor, with 6 stages: PM>10.2, PM10.2-4.2, PM4.2-2.1, PM2.1-1.3, PM1.3-0.69 and PM<0.69. Collected PM samples were extracted with organic solvents and the organic composition (Polycyclic aromatic hydrocarbons (PAHs), n-alkanes and carboxylic acids) was determined by GC-MS. Sources of the organic species were assessed using molecular PAH diagnostic ratios, carbon preference index and wax percentages. More than 70% of the PM-bound PAHs were quantified in submicron particles. Similarly, 34–42% of n-alkanes and approximately 30% of the carboxylic acids were found on the smallest particles. The main sources of the PM-bound organic species were considered as the anthropogenic emissions such as coal and biomass combustion and also vehicular emissions rather than the biogenic sources. Considerably high cancer risk levels were obtained through inhalation of PAHs. Seasonal variations and size distributions of the carboxylic acids and levoglucosan were also evaluated. Polar organic compound concentrations were higher in the summer period at both locations probably due to the higher sunlight intensity and temperature favoring their photochemical formation.

Free and combined L- and D-amino acids in Arctic aerosol

Aerosol samples were collected with a high-volume cascade impactor with a 10 day sampling frequency at the Gruvebadet observatory, close to Ny-Ålesund (Svalbard Islands). A total of 42 filters were analyzed for free and combined amino acids, as they are key components of bio-aerosol. This article provides the first investigation of free and combined L- and d-amino acids in Arctic atmospheric particulate matter. The main aim of this study was to determine how these compounds are distributed in size-segregated aerosols after short-range and long-range atmospheric transport and understand the possible sources of amino acids. The total load of free amino acids ranged from 2.0 to 10.8 pmol m−3, while combined amino acids ranged from 5.5 to 18.0 pmol m−3. At these levels amino compounds could play a role in the chemistry of cloud condensation nuclei and fine particles, for example by influencing their buffering capacity and basicity. Free and combined amino acids were mainly found in the fine aerosol fraction (<0.49 μm) and their concentrations could be affect by several sources, the most important of which were biological primary production and biomass burning.

Size-segregated urban aerosol characterization by electron microscopy and dynamic light scattering and influence of sample preparation

Size-segregated particulate matter (PM) is frequently used in chemical and toxicological studies. Nevertheless, toxicological in vitro studies working with the whole particles often lack a proper evaluation of PM real size distribution and characterization of agglomeration under the experimental conditions. In this study, changes in particle size distributions during the PM sample manipulation and also semiquantitative elemental composition of single particles were evaluated. Coarse (1–10 μm), upper accumulation (0.5–1 μm), lower accumulation (0.17–0.5 μm), and ultrafine (<0.17 μm) PM fractions were collected by high volume cascade impactor in Prague city center. Particles were examined using electron microscopy and their elemental composition was determined by energy dispersive X-ray spectroscopy. Larger or smaller particles, not corresponding to the impaction cut points, were found in all fractions, as they occur in agglomerates and are impacted according to their aerodynamic diameter. Elemental composition of particles in size-segregated fractions varied significantly. Ns-soot occurred in all size fractions. Metallic nanospheres were found in accumulation fractions, but not in ultrafine fraction where ns-soot, carbonaceous particles, and inorganic salts were identified. Dynamic light scattering was used to measure particle size distribution in water and in cell culture media. PM suspension of lower accumulation fraction in water agglomerated after freezing/thawing the sample, and the agglomerates were disrupted by subsequent sonication. Ultrafine fraction did not agglomerate after freezing/thawing the sample. Both lower accumulation and ultrafine fractions were stable in cell culture media with fetal bovine serum, while high agglomeration occurred in media without fetal bovine serum as measured during 24 h.

The effect of meteorological conditions on aerosol size distribution in Istanbul

Ambient aerosols were sampled by a high-volume cascade impactor in Istanbul, through May 2012 and November 2014. Seventy-eight size-segregated samples were gathered within the period at six different stages. The particles exhibited tri-modal distribution. The peak at 7.2 and 7.2–3 μm had a strong relation, indicating same sources. Increased relative humidity enriched 0.95–1.5-μm particle fraction in winter. Particles between 0.49 and 3 μm were inversely related to ambient temperature. Dilution effect of the wind was significant for PM1.5. Wind acted as a source for larger particles by carrying them from other source regions. Multiple linear regression was applied to particulate matter fractions in order to model the concentrations of each fraction related to meteorological data. In the model, the particle fractions of 1.5–0.95 and 0.95–0.49 μm exhibited the highest prediction performance.

Artefacts in semivolatile organic compound sampling with polyurethane foam substrates in high volume cascade impactors

ABSTRACTPolyurethane foam (PUF) is known to sorb gas-phase semivolatile organic compounds (SVOCs) from ambient air and is used routinely in conventional high volume filter-sorbent sampling of such pollutants. PUF rings have also been employed as impaction substrates in a high volume cascade impactor (HVCI) used as a sampler for the evaluation of particle toxicity. Though nonvolatile particles (e.g., trace metals, inorganic ions) have been the primary focus, the sampler has also been used to measure particulate SVOC concentrations in ambient air. The aim of this work is to investigate the validity of the latter approach. The results of three sets of experiments conducted in Canada and Denmark are reported herein. Model compounds included native and deuterated polycyclic aromatic hydrocarbons (PAHs). The experiments demonstrated that HVCI PUF substrates sorb gas-phase PAH compounds and that the sorbed mass is subject to mobilization through and out of the sampler. Particulate concentrations of low molecular...

Gas and particle size distributions of polychlorinated naphthalenes in the atmosphere of Beijing, China

Polychlorinated naphthalenes (PCNs) were listed as persistent organic pollutants in the Stockholm Convention in 2015. Despite numerous studies on PCNs, little is known about their occurrence in atmospheric particulate matter of different sizes. In this study, 49 PCN congeners were investigated for their concentrations and size-specific distributions in an urban atmosphere, and preliminary exposure assessments were conducted. Ambient air samples were collected using a high-volume cascade impactor for division into a gas fraction and four particle size fractions. Samples were collected from October 2013 to June 2014 at an urban site in Beijing, China. The concentration range for PCNs in the atmosphere (gas + particle fractions) was 6.77–25.90 pg/m3 (average 16.28 pg/m3). The particle-bound concentration range was 0.17–2.78 pg/m3 (average 1.73 pg/m3). Therefore, PCNs were mainly found in the gas phase. The concentrations of PCNs in a fraction increased as the particle size decreased (dae > 10 μm, 10 μm ≥ dae > 2.5 μm, 2.5 μm ≥ dae > 1.0 μm and dae ≤ 1.0 μm). Consequently, PCNs were ubiquitous in inhalable fine particles, and the ΣPCNs associated with PM1.0 and PM2.5 reached 68.4% and 84.3%, respectively. Tetra-CNs and penta-CNs (the lower chlorinated homologues) predominated in the atmosphere. The homologue profiles in different size particles were almost similar, but the particulate profiles were different from those in the gas phase. Among the individual PCNs identified, CN38/40, CN52/60 and CN75 were the dominant compounds in the atmosphere. CN66/67 and CN73 collectively accounted for most of the total dioxin-like TEQ concentrations of the PCNs. Exposure to toxic compounds, such as PCNs present in PM1.0 or PM2.5, may affect human health. This work presents the first data on size-specific distributions of PCNs in the atmosphere.

Evolution of size-segregated aerosol mass concentration during the Antarctic summer at Northern Foothills, Victoria Land

Abstract Within the framework of the Italian National Programm for Antarctic Research (PNRA), the first direct gravimetric measurements of size-segregated aerosol fractions were carried out at Faraglione Camp, ∼3-km far from the Italian station “M. Zucchelli” (Terra Nova Bay, Ross Sea), during the 2014–2015 austral summer. A six-stage high-volume cascade impactor with size classes between 10 μm and 0.49 μm, and, in parallel, for comparison purposes, a PM 10 high-volume sampler (50% cut-off aerodynamic diameter of 10 μm) were used. A 10-day sampling strategy was adopted. Aerosol mass measurements were carried out before and after exposure by using a microbalance specifically designed for the filter weight and placed inside a glove bag in order to maintain stable temperature and humidity conditions during weighing sessions. Measured atmospheric concentrations (referred to the “actual air conditions” of mean temperature of 268 K and mean pressure of 975 hPa) of size-segregated aerosol fractions showed the following values, given as size range, means (interquartile range): D p −3 ; 0.49–0.95 μm, 0.20 (0.19–0.24) μg m −3 ; 0.95–1.5 μm, 0.16 (0.13–0.21) μg m −3 ; 1.5–3.0 μm 0.075 (0.05–0.11) μg m −3 ; 3.0–7.2 μm 0.12 (0.02–0.19) μg m −3 ; 7.2–10 μm 0.06 (0.01–0.03) μg m −3 . The average mass concentration of the total PM 10 at Faraglione Camp for the entire sampling period was 0.92 (0.67–1.1) μg m −3 . Although a great variability, the aerosol mass concentration showed a tri-modal distribution, with an accumulation mode (in the range 0.1–1.0 μm) and two coarse modes (CM1 in the range 1.0–3.0 μm, and CM2 in the range 3.0–10 μm). From 50% to 90% of the PM 10 mass comes from particles of a size smaller than 1.0 μm. The two coarse modes represented from ∼5% to ∼35% of the PM 10 , showing opposite seasonal trends (CM1 decreased while CM2 increased). During summer, PM 10 mass concentration increased to a maximum of ∼1.6 μg m −3 at mid-December, while in January it decreased to values that are typical of November. Both accumulation and upper super-micron fractions showed a maximum in the same period contributing to the PM 10 peak of mid-summer.

Protein amino acids as markers for biological sources in urban aerosols

Biological aerosol particles are recently gaining increased attention, but global estimates of their emissions are unclear. Traditional organic tracers for biological particles have not been able to capture the diversity of biological sources such as residential wood burning. Here, we have analyzed protein content in air particulate matter over a year in a suburban area near Shibuya, in order to identify contributions from biological sources. Aerosols were separated into five size fractions using a high-volume cascade impactor. Amino acid profiles were obtained from acid hydrolysates by high-performance liquid chromatography and were subsequently used in a receptor model for source apportionment. Results show that protein content ranged from 0.5 to 2 % throughout the year in all size fractions. We observed contributions from seasonally variable emission sources such as pollen and fallen leaves in coarse particles, larger than 7 µm, at elevated concentrations during spring and winter. We also found contributions from pollen and fallen leaves in the smallest size fraction, lower than 1.1 µm, after spring. This finding indicates that sources are broken up to smaller particles in the urban environment. Overall, our findings demonstrate that protein content can be used as marker for biological aerosol particles, and that protein amino acid composition can distinguish multiple sources.

Day and night variation in chemical composition and toxicological responses of size segregated urban air PM samples in a high air pollution situation

Urban air particulate pollution is a known cause for adverse human health effects worldwide. China has encountered air quality problems in recent years due to rapid industrialization. Toxicological effects induced by particulate air pollution vary with particle sizes and season. However, it is not known how distinctively different photochemical activity and different emission sources during the day and the night affect the chemical composition of the PM size ranges and subsequently how it is reflected to the toxicological properties of the PM exposures. The particulate matter (PM) samples were collected in four different size ranges (PM10-2.5; PM2.5-1; PM1-0.2 and PM0.2) with a high volume cascade impactor. The PM samples were extracted with methanol, dried and thereafter used in the chemical and toxicological analyses. RAW264.7 macrophages were exposed to the particulate samples in four different doses for 24 h. Cytotoxicity, inflammatory parameters, cell cycle and genotoxicity were measured after exposure of the cells to particulate samples. Particles were characterized for their chemical composition, including ions, element and PAH compounds, and transmission electron microscopy (TEM) was used to take images of the PM samples. Chemical composition and the induced toxicological responses of the size segregated PM samples showed considerable size dependent differences as well as day to night variation. The PM10-2.5 and the PM0.2 samples had the highest inflammatory potency among the size ranges. Instead, almost all the PM samples were equally cytotoxic and only minor differences were seen in genotoxicity and cell cycle effects. Overall, the PM0.2 samples had the highest toxic potential among the different size ranges in many parameters. PAH compounds in the samples and were generally more abundant during the night than the day, indicating possible photo-oxidation of the PAH compounds due to solar radiation. This was reflected to different toxicity in the PM samples. Some of the day to night difference may have been caused also by differing wind directions transporting air masses from different emission sources during the day and the night. The present findings indicate the important role of the local particle sources and atmospheric processes on the health related toxicological properties of the PM. The varying toxicological responses evoked by the PM samples showed the importance of examining various particle sizes. Especially the detected considerable toxicological activity by PM0.2 size range suggests they're attributable to combustion sources, new particle formation and atmospheric processes.

Variation of the group 5 grass pollen allergen content of airborne pollen in relation to geographic location and time in season

Allergies to grass pollen are the number one cause of outdoor hay fever. The human immune system reacts with symptoms to allergen from pollen. We investigated the natural variability in release of the major group 5 allergen from grass pollen across Europe. Airborne pollen and allergens were simultaneously collected daily with a volumetric spore trap and a high-volume cascade impactor at 10 sites across Europe for 3 consecutive years. Group 5 allergen levels were determined with a Phl p 5-specific ELISA in 2 fractions of ambient air: particulate matter of greater than 10 μm in diameter and particulate matter greater than 2.5 μm and less than 10 μm in diameter. Mediator release by ambient air was determined in FcεRI-humanized basophils. The origin of pollen was modeled and condensed to pollen potency maps. On average, grass pollen released 2.3 pg of Phl p 5 per pollen. Allergen release per pollen (potency) varied substantially, ranging from less than 1 to 9 pg of Phl p 5 per pollen (5% to 95% percentile). The main variation was locally day to day. Average potency maps across Europe varied between years. Mediator release from basophilic granulocytes correlated better with allergen levels per cubic meter (r(2) = 0.80, P < .001) than with pollen grains per cubic meter (r(2) = 0.61, P < .001). In addition, pollen released different amounts of allergen in the non-pollen-bearing fraction of ambient air, depending on humidity. Across Europe, the same amount of pollen released substantially different amounts of group 5 grass pollen allergen. This variation in allergen release is in addition to variations in pollen counts. Molecular aerobiology (ie, determining allergen in ambient air) might be a valuable addition to pollen counting.

Particle size distribution of halogenated flame retardants and implications for atmospheric deposition and transport.

This study investigates the distribution of polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCD) and a group of novel flame retardants (NFRs) on atmospheric aerosols. Two high volume cascade impactors were used to collect particulate fractions of ambient air over a one year period at urban and rural sites. The majority of FRs were found on the finest aerosols (<0.95 μm). Concentrations of HBCD were higher than those of ΣPBDEs. Moreover, we noted seasonality and spatial differences in particle size distributions, yet a large portion of the observed differences were due to differences in particulate matter (PM) itself. When normalized by PM, the size distributions of the FRs exhibited much greater heterogeneity. Differences existed between the FR distributions by molecular weight, with the higher molecular weight FRs (e.g., BDE-209, Dechlorane Plus) distributed more uniformly across all particulate size fractions. The seasonal, spatial, and compound-specific differences are of crucial importance when estimating dry and wet deposition of FRs as smaller aerosols have longer atmospheric residence times. Estimated wet and dry deposition of four representative FRs (BDE-47, BDE-209, HBCD, and Dechlorane Plus) using size-segregated aerosol data resulted in lower deposition estimates than when bulk aerosol data were used. This has implications for estimates of long-range atmospheric transport and atmospheric residence times, as it suggests that without size-specific distributions, these parameters could be underestimated for FRs.

Water-soluble inorganic ions in urban aerosols of the continental part of Balkans (Belgrade) during the summer – autumn (2008)

Abstract Size-segregated aerosol samples were collected using six stages High Volume Cascade Impactor. Aerosol mass and water soluble ions concentrations were determined. The Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model was used to study the origin of air masses arriving to Belgrade in the investigated period. The obtained results of aerosol mass and water-soluble ion concentrations have been divided into six sub-data sets based on air mass categories. The highest average mass concentration of the fine mode (Dp ≤ 0.49 μm) was found for air masses coming to Belgrade from the southeast and northwest directions, and of the coarse mode (3.0 &lt; Dp ≤7.2 μm) for air masses arriving from the northwest direction. The highest concentrations of SO4 2– were found in the fine particles transported to the investigated area by air masses from southeast direction. The analysis of contribution of marine aerosol components (Na+ and Cl-), the Correlation and Cluster Analysis indicated the influence of marine aerosol on urban aerosol of the central Balkans coming from the Western Mediterranean and northern direction. NH4 + and SO4 2- and K+ dominated in the fine mode for all air mass categories. PCA demonstrated the dominant impact of secondary aerosol formation processes on urban aerosols.

Size fractionated aerosol composition at roadside and background environments in the Madrid urban atmosphere

The chemical composition of size-segregated particulate matter (PM) was studied during summer and winter sampling campaigns, at two different urban sites (roadside and urban background) in the city of Madrid, Spain. PM was sampled with high volume cascade impactors, in 4 size ranges: 10–2.5, 2.5–1, 1–0.5 and <0.5μm. The carbonaceous content (OC and EC) was determined by a thermo-optical method, whilst the water soluble ionic species were measured by ion chromatography. The most common synoptic meteorological situations, including those causing the transport of African dusty air masses, were identified in both seasons. Whether the PM10 mass or the highest concentrations of EC and OC were found predominantly in the ultrafine size fraction at both sites. In contrast with roadside, at the urban background, the particle mass concentrations for the different size ranges were statistically higher in summer than in winter. Observed inter-site differences suggest the existence of other sources and formation processes contributing in the summer period to the levels of PM at the urban background site apart from road traffic emissions. Secondary organic carbon (SOC) showed a clear seasonal pattern, with much higher concentrations in summer than in winter in both places, as well as higher relative contributions at the urban background than at the road traffic site. (NH4)2SO4 levels were at their maximum at both sites in summer in PM0.5. Differently, higher values were reached in winter for NH4NO3 in PM0.5 and for NaCl in PM2.5–10. From the ion balances, it was observed that, in summer, the formation of secondary inorganic compounds included an unusual enrichment in Ca2+ in the submicrometre fraction, either at roadside or at urban background.