Published papers

Mass gathering events in Japan have gradually mitigated their novel coronavirus disease (COVID-19) control regulations, along with a minimum infection risk. The Japan Professional Football League (J.League) conducted pilot surveys on holding events with chant cheers. In this commentary, we introduce the collaborative efforts based on scientific knowledge among experts, J.League, and their fans. We performed risk assessment in advance, by updating a previously developed model. We further observed the average proportion of masks worn, chant cheering time of participants, and CO2 levels in the stand. The number of new COVID-19 cases in an event with 5,000 chant cheering participants and 35,000 non-chant cheering participants was estimated to be 1.02 times of an event, with 40,000 non-chant cheering participants. The average proportion of masks worn during the game was 98.9 %, for chant cheer participants. The chant cheering participants spent 50.0–51.1 % of their time chant cheering. Monitored average CO2 levels were ≤ 540 ppm, suggesting high ventilation rates in the stand. The high proportion of masks worn represents the willingness of norm-conscious fans to cooperate in regular recovery of the sport. This has proved to be one of the successful models for future mass gathering events.

Conventional methods for collecting and extracting aerosol particles are challenging in accurately characterizing particle-bound polycyclic aromatic hydrocarbons (PAHs) contamination and conducting cellular exposure studies. Therefore, developing direct aerosol sample collection and simple pretreatment analytical methods is necessary. This study describes the optimization of the QuEChERS (quick, easy, cheap, effective, rugged, and safe) extraction method for the determination of PAHs in powder-form environmental standard materials (SRM1944) and proves it is also effective for analyzing PAHs in powder aerosol particle samples collected by cyclone. In this study, we used an I-optimal design response surface method combined with a desirability function to investigate the extraction effect of PAHs under different combinations of QuEChERS extraction factors, including extraction solvent, salt, and clean-up reagent. The optimized conditions of the method were determined using the 2-factor interaction (2FI) model combined with boundary conditions, resulting in acetonitrile/dichloromethane (7:1, v/v), Na2SO4/NaCl (1:1, w/w), and primary and secondary amine (PSA) as extraction solvents, extraction salts, and clean-up reagent, respectively. The optimized method showed good recoveries of PAHs reaching 76%–118% and 85%–121% for SRM1944 and standard solution. The results for cyclone-collected ambient powder aerosol particles extracted by the optimized QuEChERS illustrated that this improved procedure has good PAHs extraction efficiency as the traditional Soxhlet method, while reducing hazardous organic solvents usage, experimental cost (per mg sample) by 97% and sample pretreatment time. Overall, this combination of “powder aerosol particle collection and modified QuEChERS extraction” provides new insight on aerosol sample collection, extraction, and in vitro/in vivo exposure studies.

The respiratory effects of particulate matter (PM) in subway station platforms or tunnels have attracted considerable research attention. However, no studies have characterized the effects of subway PM on allergic immune responses. In this study, iron oxide (α-Fe2O3 and Fe3O4) particles—the main components of subway PM—were intratracheally administered to BALB/c mice where ovalbumin (OVA) induced allergic pulmonary inflammation. Iron oxide particles enhanced OVA-induced eosinophil recruitment around the bronchi and mucus production from airway epithelium. The concentrations of type 2 cytokines, namely, interleukin (IL)-5 and IL-13, in bronchial alveolar lavage fluids were increased by iron oxide particles. Iron oxide particles also increased the number of type 2 innate lymphoid cells and CD86+ cells in the lung. Moreover, phagocytosis of particles in lung cells was confirmed by Raman spectroscopy. In a subsequent in vitro study, bone marrow-derived antigen-presenting cells (APCs) isolated from NC/Nga mice were exposed to iron oxide particles and OVA. They were also exposed to outdoor ambient PM: Vehicle Exhaust Particulates (VEP) and Urban Aerosols (UA) as references. Iron oxide particles promoted the release of lactate dehydrogenase, C-X-C motif chemokine ligand 1 and IL-1α from APCs, which tended to be stronger than those of VEP. These results suggest that iron oxide particles enhance antigen presentation in the lungs, promoting allergic immune response in mice; iron oxide particles-induced death and inflammatory response of APCs can contribute to allergy exacerbation. Although iron oxide particles do not contain various compounds like VEP, iron oxide alone may have sufficient influence.

Iron (Fe), the main component of non-exhaust particulates, is known to have variable health effects that depend on the chemical species of iron. This study characterized the possible contribution of iron oxides and hydroxides to airborne brake wear particles under realistic vehicle driving and braking conditions with different brake pad friction materials. We found significant differences in wear factors and PM10 and PM2.5 emissions between non-asbestos organic (NAO) and European performance (ECE) brake pads. Iron was the dominant contributor to PM10 and PM2.5 brake wear particles for both NAO and ECE. The iron concentration ratio in the particle mass (PM) was comparable to the disc-to-pads ratio measured by wear mass. The fact that magnetite, which is of interest with respect to health effects, was less abundant in NAO than in ECE suggested that tribo-oxidations occurred in NAO. Metallic iron is generated not only from abrasive wear but also from tribo-chemical reduction with magnetite as the starting material. We found that there were differences in PM emissions between brake friction materials, and that the phase transformations of iron differed between friction materials. These differences were apparent in the distribution of iron oxides and hydroxides. Heat, tribo-oxidation, and tribo-reduction are intricately involved in these reactions.

The charging state of submicron particles strongly affects the number of particles deposited on the inner surface of human airways during inhalation, and an increase in this number leads to adverse effects on human health. However, the key factors controlling the charging state of particles are poorly understood because of the limited measurements of the number concentrations of charged submicron particles. In order to experimentally investigate the key factors controlling the number concentration of charged particles, the technique for accurately measuring the number concentration of non-charged particles (Nnon-charge) was improved based on a system consisting of optical particle counters and a parallel-plate particle separator to which a high voltage (1.0–1.5 kV) was applied. The ratio of the Nnon-charge to the total number concentration of particles (Ntotal), with diameters 0.3–0.5 µm, was used as a metric of the number fraction of non-charged particles. A decrease in the Nnon-charge/Ntotal ratio with an increase in the negative ion concentration (nion–) and the nion–/Ntotal ratio under stable meteorological conditions showed an increase in the number of charged particles by collisions between aerosols and ions. Under fluctuating humidity conditions, the Nnon-charge/Ntotal ratio also decreased with an increase in the nion– and the nion–/Ntotal ratio. Particularly, the decrease rate in the Nnon-charge/Ntotal ratio was greater at higher nion– and nion–/Ntotal ratio values than that under stable meteorological conditions. This suggests that the generation of water vapor drives an increase in ion concentration, leading to frequent collisions between excessive negative ions and aerosols. A quantitative understanding of the changes in the number fraction of charged particles with increasing humidity and nion– can assist in estimating the number of particles deposited on the inner surface of human airways.

Spatial distributions of interleukin-8 (IL-8)-based relative inflammation potentials (IP) of PM2.5 from vehicle exhaust and non-exhaust emission sources in Japan are derived using the meteorology–chemistry model (NHM-Chem) and laboratory experiments. In this study, IP is first defined as multiplying PM2.5 from different emission sectors by supernatant IL-8 concentrations released using PM2.5 samples, normalized to that of particle-free controls. The simulated IP of primary exhaust particles IP(E) accounts for 3%–30% of the total vehicle IP (exhaust + non-exhaust, primary + secondary), IP(V), which is low in densely populated regions (3%–15%) and high (5%–30%) in less populated regions, because there are fewer exhaust PM2.5 emitters (diesel trucks) in more populated regions. The contribution of IP(V) to IP of the total environmental PM2.5, IP(A), varied substantially in space by approximately 3–5 times (the contributions are greater in larger cities as there is more traffic). In our estimates, IP(V) is approximately one and two orders of magnitude higher than IP(E) and IP(T), the IP of fresh tire wear particles (TWPs), respectively. IP(T) has a minor contribution to IP(V) and IP(A). Recently, however, aged TWPs have been reported to be toxic; thus, the aging process of TWPs needs to be considered in the future.

Microplastics are ubiquitous in the atmosphere, leading to human exposure through inhalation. Airborne microplastics undergo degradation due to sunlight irradiation, yet the respiratory risks associated with degraded microplastics remain poorly understood. In this study, we investigated the respiratory effects of polyethylene terephthalate (PET) degraded by artificial sunlight and created a transport and degradation model of PET for risk assessment. PET fibers were cut and subjected to artificial sunlight irradiation. Mice exposed to aged PET showed increased airway resistance induced by methacholine (MCh) inhalation, along with lung inflammation and neutrophil infiltration. Terephthalic acid (TPA) was continuously released from PET aged by artificial sunlight. Exposure to TPA also caused lung inflammation and enhanced airway resistance induced by MCh in mice. These findings indicate that aged PET can cause respiratory impairment via TPA release. A simple transport and degradation model was developed to quantitatively relate the abundance of aged PET produced in this study (i.e. 4,000 × 96 W m-2 h) and aged fractions of PET that can be generated in the atmosphere. Our results suggested 10% to 60% of PET was degraded as that produced in this study over sunny regions in summer, whereas only lower than 1% in high-latitude cities in Europe in winter. This study demonstrates the importance of considering the abundance of aged PET and further development of a transport and degradation model of PET to assess the risk of degraded PET in the atmosphere.

Exposure to fine particulate matter (PM2.5) has been epidemiologically reported to wors-en the prognosis of ischemic stroke; however, the details have not been investigated. One of the major toxic mechanisms of PM2.5 inhalation is oxidative stress, which is mediated by reactive oxygen species generated by PM2.5 components such as metals and polycyclic aromatic hydrocarbons. In this study, we examined the effects of long-term exposure to urban particulate matter, focusing on oxidative stress, on prognosis after ischemic stroke in mice. When mice were intranasally exposed for 28 days to an urban aerosol collected in Beijing, China (CRM28), microglial activation was observed in the cerebral cortex, indicating that CRM28 induced neuroinflammation. CRM28 exposure resulted in increased serum levels of brain natriuretic peptide and troponin I, suggesting that cardiac injury was elicited by CRM28. Lung inflammation was also observed following CRM28 exposure; however, systemic inflammation was not detected. Mice exposed to CRM28 showed an exacerbation of mortality after ischemic stroke induction compared with vehicle mice. A vitamin E-rich diet suppressed CRM28-induced lipid peroxidation in the heart and lungs but not in the brain. A vitamin E-rich diet also attenuated cardiac injury and lung inflammation induced by CRM28 exposure, whereas neuroinflammation was not affected. Mortality after ischemic stroke improved with the administration of a vitamin E-rich diet. Considering that systemic inflammation did not occur, cardiac injury induced by oxidative stress under exposure to urban particulate matter may be involved in increased mortality after ischemic stroke. Antioxidation under air pollution is fundamental for protection against ischemic stroke.

This study reports contact pressure-sliding speed maps for friction, wear and particle emissions from high-speed train brakes. Two particle spectrometers measured the airborne wear particles generated with a pin-on-disc tribometer. Particles were characterized with transmission electron microscopy and energy dispersive X-ray fluorescence. The results indicate that both the friction and wear of brake pads and discs gradually decreased as sliding speed increased, which showed less dependence on contact pressure. Particle concentrations gradually increased with increasing sliding speed. Low contact pressure and sliding speed tended to generate particles smaller than 2.5 μm. The train brake emitted particles had higher average geometric mean diameters than the car brake emitted particles, which were primarily composed of iron, copper and chromium and were oxidized.

In this study, we measured polycyclic aromatic hydrocarbons (PAHs) in aerosols in Xi'an, China from 2005 to 2007, by using a modified Soxhlet extraction followed by a clean-up procedure using automated column chromatography followed by HPLC/fluorescence detection. The sources of PAHs were apportioned by using the positive matrix factorization (PMF) method. The PM10 concentration in winter (161.1 ± 66.4 μg m- 3, n = 242) was 1.5 times higher than that in summer (110.9 ± 34.7 μg m- 3, n = 248). ΣPAH concentrations, which are the sum of the concentrations of all detected PAHs, in winter (344.2 ± 149.7 ng m- 3, n = 45) was 2.5 times higher than that in summer (136.7 ± 56.7 ng m- 3, n = 24) in this study. These strong seasonal variations in atmospheric PAH concentration are possibly due to coal combustion for residential heating. According to the source apportionment with PMF method in this study, the major sources of PAHs in Xi'an are categorized as (1) mobile sources such as vehicle exhaust that constantly contribute to PAH pollution, and (2) stationary sources such as coal combustion that have a large contribution to PAH pollution in winter. © 2010 Elsevier B.V. All rights reserved.

Biological contamination of fresh produce by fungi in storage is becoming a serious problem. Gaseous chlorine dioxide (ClO2) has been used to prevent fungal growth on fresh produce; however, the specific effects of gaseous ClO2 at concentrations low enough to be safe for the human body on fungal growth remain unknown. Therefore, in this study, we aimed to investigate the effect of low-concentration gaseous ClO2 on fungal growth in sweet potatoes over 1 month. Here, a mechanochemical reaction involving the collision of two types of powders was used to produce low concentrations of gaseous ClO2. The experiment was conducted in a container and chlorine dioxide gas was diffused by a circulator to verify its microbiostatic effect in a large space. A clear microbiostatic effect was observed in potatoes without skin when exposed to low-concentration ClO2 for 3 days. Notably, low concentrations (< 1.0 ppm) of ClO2 reduced Rhizopus stolonifer growth in sweet potatoes with skin over 1 month. Therefore, low concentrations of gaseous ClO2 are sufficient to inhibit fungal growth via gas diffusion.

Chronic obstructive pulmonary disease (COPD) is induced by inhalation of toxic substances such as cigarettes and air pollution. Dry powder inhalers (DPIs) are the primary treatment for these diseases. However, they have some problems, such as residuals in a capsule caused by electrostatic force before reaching the human lungs. This study investigated the particle tribocharging mechanism in a DPI using a tandem differential mobility analyzer (TDMA) and a combined discrete element method and computational fluid dynamics (DEM-CFD) approach. In the TDMA experiment, the charging state of the particles changed from negative to positive charge in the DPI device fabricated by the 3D printer. This is because tribocharging is caused by particle–particle collisions and particle–wall collisions. In the numerical simulation, particle–wall collisions occurred more frequently than particle–particle collisions. Therefore, the particle–wall collisions change the charging state of the particle in the DPI device. These results suggest that collisions between particles and walls of the device cause the particles to become charged, leading to a decrease in their deposition in the deeper regions of the lungs. Moreover, the large turbulence kinetic energy of the airflow in the DPI device caused particle–wall collisions because the particles were widely dispersed in the DPI device. These results suggest that optimum turbulence kinetic energy is necessary to reduce particle aggregation and improve the delivery efficiency of DPIs to the human lungs.

We report measurement of molecular and carbon isotopic compositions of atmospheric polycyclic aromatic hydrocarbons (PAHs) in three Chinese cities, Beijing, Chongqing, and Hangzhou. Precision of δ13C measurement by GC/C/ IRMS ranged from 0.4 to 0.7‰, and accuracy ranged from 0.0 to 0.4‰. δ13C of atmospheric PAHs ranged from -22.9 to -27.2‰ for Chongqing, from -24.2 to -26.8‰ for Hangzhou, from -21.1 to -26.1‰ for Beijing summer and from -22.5 to -25.7‰ for Beijing winter. Atmospheric PAHs of both Chongqing and Hangzhou become more depleted in 13C with increasing PAH molecular weight. On the other hand, atmospheric PAHs in Beijing become more enriched in 13C with increasing PAH molecular weight. The difference of isotopic signature between "Beijing" and "Chongqing + Hangzhou" is statistically significant (t-test, P < 0.05). The isotopic trends of PAHs in Chongqing and Hangzhou are similar to that obtained from fluidized-bed coal combustion particles, whereas the isotopic trend of PAHs in Beijing air is similar to that obtained from automotive exhaust particles. According to this observation, it appears that automotive exhausts significantly affect PAH loading to Beijing air and that coal combustion is the main cause of PAH existence in Chongqing and Hangzhou air. While the isotopic signatures can classify the three Chinese cities into two groups, the molecular profiles do not show a clear trend among them. This can be explained by the following description: carbon isotopic signatures of PAHs are expected to have source- and/or combustion field-specific values and patterns mainly, whereas molecular compositions of PAHs depend on various factors such as source material, burning temperature, air/fuel ratio, and environmental alteration during transport. © 2002 Elsevier Science Ltd. All rights reserved.

A quantitative apportionment of polycyclic aromatic hydrocarbons (PAHs) derived from fossil fuel combustion (14C-free) and biomass burning (contemporary 14C) was carried out using a recently developed compound-specific radiocarbon analysis (CSRA) method for a sediment core from an urban reservoir located in the central Tokyo metropolitan area, Japan. The 14C abundance of PAHs in the sediments was measured by accelerator mass spectrometry (AMS) after extraction and purification by three types of column chromatography, by high performance liquid chromatography (HPLC), and, subsequently, by a preparative capillary gas chromatography (PCGC) system. This method yielded a sufficient quantity of pure compounds and allowed a high degree of confidence in the determination of 14C. The fraction modern values (fM) of individual PAHs (phenanthrene, alkylphenanthrenes, fluoranthene, pyrene and benz[a]anthracene) in the sediments ranged from 0.06 to 0.21. These results suggest that sedimentary PAHs (those compounds mentioned above) were derived mostly from fossil fuel combustion. Three sectioned-downcore profiles (∼40 cm) of the 14C abundance in phenanthrene and alkylphenanthrenes showed a decreasing trend with depth, that was anti-correlated with the trend of ∑PAHs concentration. The fM values of phenanthrene were also larger than those of alkylphenanthrenes in each section of the core. This result indicates that phenanthrene received a greater contribution from biomass burning than alkylphenanthrenes throughout the core. This finding highlights the method used here as an useful approach to elucidate the source and origin of PAHs in the environment. © 2004 Elsevier B.V. All rights reserved.

This paper describes the daily concentrations of trace metals and ionic constituents in the aerosol of Beijing, China from March 2001 to August 2003. Daily PM 10 concentrations were also measured from September 2001 to August 2003. The daily average PM 10 concentration at Beijing, China from September 2001 to August 2003 was 171±117 μg m -3 (n=673), which is 5-fold higher than at Yokohama, Japan. Trace metal concentrations were analyzed by using inductively coupled plasma mass spectrometry equipped with a laser ablation sample introduction (LA/ICP-MS), which is a rapid and simultaneous method for multi-element analysis. The daily average metal concentrations in TSP in Beijing from March 2001 to August 2003 were: Al: 3.5±2.4 (n=727), Ti: 0.47±0.35 (n=720), V: 0.013±0.010 (n=716), Cr: 0.019±0.015 (n=618), Mn: 0.24±0.16 (n=730), Fe: 5.5±3.9 (n=728), Co: 0.0046±0.0055 (n=629), Ni: 0.022±0.024 (n=680), Cu: 0.11±0.11 (n=660), Zn: 0.77±0.60 (n=726), As: 0.048±0.047 (n=731), Se: 0.010±0.010 (n=550), Cd: 0.0068±0.0082 (n=709), Sb: 0.033±0.036 (n=687), and Pb: 0.43±0.50 (n=728) (unit, μg m -3). All the metal concentrations in TSP in Beijing, China were 1.7-21.8 times higher than those in TSP in the center of Tokyo, Japan. Notably, As concentrations in TSP in Beijing were 20-fold higher than those in Tokyo. Source identification of aerosols in Beijing was carried out by using the chemical mass balance (CMB) receptor model, with the daily concentration of metals in the aerosol. The major primary sources of the aerosol of Beijing were considered to be soil dust and coal combustion. Vehicle exhaust contribution tended to increase. © 2004 Elsevier B.V. All rights reserved.

The use of a platinum-cerium bimetallic fuel additive has been proposed as a cost-effective strategy for reducing particulatematter (PM) andNOx emissions fromdiesel-powered engines.Although previous studies have demonstrated that the use of platinum-cerium bimetallic fuel additive reduced emissions from diesel engines, there have been no reported investigations of howthe use of these fuel-borne catalysts (FBCs) impact the chemical and physical properties of diesel PMemissions. The present study demonstrates that the use of a platinum-cerium bimetallic fuel additive has a significant impact on the detailed chemical composition and size distribution of PM emitted from a diesel engine. Tests were conducted to explore the impact of different fuel concentrations of the fuel-borne catalyst at different engine-operating conditions. These tests were performed with a medium-duty diesel engine that was not equipped with exhaust gas recirculation or a diesel particulate filter (DPF). The results demonstrated that the use of the additive significantly reduced the emissions of PM2.5 and carbonaceous species. The reduction was 34% for thePM2.5mass, 54% for thePM2.5 elemental carbon, and 23%for thePM2.5 organic carbonwhen 0.1 ppmPt and 7.5ppmCe of the additivewere used. Emissions of particle-phase metals originating from the additive had a significant contribution to particle matter emissions when 0.7 ppm Pt and 42 ppm Ce of the additive were used. The particle size distribution of platinum in the PMemissions was different from the size distribution of cerium. The cerium/ platinum ratio in thePM2.5 diesel particle emissions ranged from 119 to 656, which was much higher than the ratio in the fuel additive that was 58.5 ( 5.6, indicating a higher penetration of cerium through the engine. copyright © 2009 American Chemical Society.

The summer of 2003 was an active forest fire season in Siberia. Several events of elevated carbon monoxide (CO) were observed at Rishiri Island in northern Japan during an intensive field campaign in September 2003. A simulation with a global chemistry-transport model is able to reproduce the general features of the baseline levels and variability in the observed CO, and a source attribution for CO in the model suggests that the contribution from North Asia dominated, accounting for approximately 50% on average, with contributions of 7% from North America and 8% from Europe and 30% from oxidation of hydrocarbons. With consideration of recent emission estimates for East Asian fossil fuel and Siberian biomass burning sources, the model captures the timing and magnitude of the CO enhancements in two pollution episodes well (17 and 24 September). However, it significantly underestimates the amplitude during another episode (11-13 September), requiring additional CO emissions for this event. Daily satellite images from AIRS reveal CO plumes transported from western Siberia toward northern Japan. These results suggest that CO emissions from biomass burning in western Siberia in 2003 are likely underestimated in the inventory and further highlight large uncertainties in estimating trace gas emissions from boreal fires. © 2009 The Author Journal compilation © 2009 Blackwell Munksgaard.

© 2010 Asian Journal of Atmospheric Environment. Filter-based sampling techniques are the conventional way to collect particulate matter, but particles collected and entangled in the filter fibers are difficult to be removed and thus not suited for the following cell- and animal-based exposure experiments. Collecting aerosol particles in powder form using a cyclone instead of a filter would be a possible way to solve this problem. We developed a hybrid virtual-impactor/cyclone high-volume fine and coarse particle sampler and assessed its performance. The developed system achieved 50% collection efficiency with components having the following aerodynamic cut-off diameters: virtual impactor, 2.4 μm; fine-particle cyclone, 0.18-0.30 μm; and coarse-particle cyclone, 0.7 μm. The virtual impactor used in our set-up had good PM2.5 separation performance, comparable to that reported for a conventional real impactor. The newly developed sampler can collect fine and coarse particles simultaneously, in combination with exposure testing with collected fine- and coarse-particulate matter samples, should help researchers to elucidate the mechanism by which airborne particles result in adverse health effect in detail.

The use of biodiesel as a replacement for petroleum-based diesel fuel has gained interest as a strategy for greenhouse gas emission reductions, energy security, and economic advantage. Biodiesel adoption may also reduce particulate elemental carbon (EC) emissions from conventional diesel engines that are not equipped with after-treatment devices. This study examines the impact of biodiesel blends on EC emissions from a commercial off-road diesel engine and simulates the potential public health benefits and climate benefits. EC emissions from the commercial off-road engine decreased by 76% when ultra-low sulfur commercial diesel (ULSD) fuel was replaced by biodiesel. Model calculations predict that reduced EC emissions translate directly into reduced EC concentrations in the atmosphere, but the concentration of secondary particulate matter was not directly affected by this fuel change. Redistribution of secondary particulate matter components to particles emitted from other sources did change the size distribution and therefore deposition rates of those components. Modification of meteorological variables such as water content and temperature influenced secondary particulate matter formation. Simulations with a source-oriented WRF/Chem model (SOWC) for a severe air pollution episode in California that adopted 75% biodiesel blended with ULSD in all non-road diesel engines reduced surface EC concentrations by up to 50% but changed nitrate and total PM2.5 mass concentrations by less than ±. 5%. These changes in concentrations will have public health benefits but did not significantly affect radiative forcing at the top of the atmosphere. The removal of EC due to the adoption of biodiesel produced larger coatings of secondary particulate matter on other atmospheric particles containing residual EC leading to enhanced absorption associated with those particles. The net effect was a minor change in atmospheric optical properties despite a large change in atmospheric EC concentrations. These results emphasize the importance of considering EC mixing state in climate research.

Detailed mechanisms of the cellular biochemical reactions associated with the toxicity of PM2.5 have not been elucidated well so far, because it is difficult to collect a sufficient amount of PM2.5 particles to carry out toxicity assays using cells. A high-volume PM2.5 particle sampler using the impactor and cyclone techniques has been developed in this study. The 50% cut-points of the impactor and cyclone for ambient aerosols at 1,100 L/min of air flow were 2.0 μm and 0.15–0.18 μm, respectively. The separation characteristics of the impactor were similar to those of the WINS impactor. The contents of EC, which is an aggregate/agglomerate of primary particles with sizes less than 100 nm, in the cyclone particles was similar to that in the filter particles. The contents of organic matter and ammonium in the particles collected using the cyclone system were lower than those in the particles collected using traditional filter sampling. We propose that the highvolume PM2.5 particle sampler developed in this study can collect a large amount of aerosol particles in a “powder form” and can also avoid certain sampling artifacts caused by the adsorption of volatile organic compounds and gaseous ammonia to particles on the filter media. The sampling device developed in this study allows researchers to collect a sufficient amount of PM2.5 particles for cell exposure studies without the use of filters.