Characteristics Of PM2 Research Articles

Characterization of PM2.5 during ACU15 campaign in Mexico City

Mexico City emits several thousands of tons of particle matter from transportation and other economic sectors. We collected PM2.5 samples from January to March 2015. The chemical analyses showed that PM2.5 is made up of 39% organic carbon, 12% elemental carbon, 23% metals (Al, Si, S, P, and K), and 5% heavy metals (Pb, Cr, Mn, Zn, and Hg). Ca and Fe were also present in trace concentrations, probably due to the resuspension of soils. Nitrate, sulfate, and ammonium suggest that the southwest of Mexico City, specifically the sampling site, receives more oxidated pollutants from vehicle emissions than other emissions. The chemical analyses show no significant changes in the composition or concentration of particle matter compared to previous studies.

Characteristics of PM2.5 and CO2 Concentrations in Typical Functional Areas of a University Campus in Beijing Based on Low-Cost Sensor Monitoring

The air quality in educational campuses affects the health and work efficiency of teachers and students. Studies into this matter are of great significance for optimizing the management of campus living environments. Low-cost online sensors to monitor PM2.5 and CO2 levels were used in typical functional areas of a university campus in Beijing, China, including offices, dormitories, leisure spaces, canteens, and laboratories. By comparing the findings with data from nearby national monitoring stations, the seasonal and spatial variations in PM2.5 and CO2 concentrations were analyzed. Findings indicate PM2.5 levels within the campus were notably lower compared to the surrounding urban environment. There was variation in PM2.5 and CO2 concentrations across different functional areas. Typically, indoor PM2.5 levels were lower than outdoor ones, while CO2 concentrations in enclosed indoor spaces with human activities progressively escalated. The main internal emission sources affecting the PM2.5 level on campus included traffic emissions, dust generated by human activities, and emissions from catering. In contrast, in areas with better green coverage or where a lake system participates in the atmospheric circulation, the PM2.5 level and CO2/PM2.5 were lower. This indicates that the cleansing impact of plants and aquatic systems is instrumental in lowering PM2.5 concentrations, offering healthier leisure spaces. Seasonal variations also impact PM2.5 levels. During the non-heating period, less pollution source emissions led to decreased outdoor PM2.5 concentrations. The campus monitoring sites experienced an approximate 5 µg/m3 and 29 µg/m3 reduction in the average PM2.5 levels as compared to the PM2.5 of the surrounding urban environment, respectively, during the non-heating and heating period. During indoor activities or sleep, CO2 levels can build up to as high as 2303 ppm due to breathing. It is advisable to stay indoors on days when pollution levels are high, whereas on days with clean air, it is healthier to be outdoors or to air out indoor areas by opening windows. Our research provides clearer scientific evidence for incorporating behavioral strategies for improving air quality into both daily work and life. Moreover, the findings are quite meaningful for the widespread adoption of low-cost sensor monitoring in various environments, with applications beyond just the campus settings.

Characterization of PM2.5 emissions from on-road vehicles in the tunnel of a major Middle Eastern city

Traffic emissions are an important source of air pollution worldwide, but in the Middle East, this problem is exacerbated by weak or no enforcement of emission regulations. Comprehensive measurements of fine PM emission factors (EFs) from road transport in the region have not yet been conducted, but such data are necessary for quantitative assessments of the health impact of transport emissions in the region. To address this need, PM2.5 samples collected inside the Salim Slam tunnel in Beirut, Lebanon were analyzed for carbonaceous matter (organic carbon (OC) and elemental carbon (EC)), water-soluble ions, elements, and selected organic compounds. The OC/EC ratio was 1.8 for the total fleet and 2.6 for light-duty vehicles (LDV), in agreement with the dominant proportion of gasoline LDV in the Lebanese fleet. A Cu/Sb ratio of 4.2 ± 0.1 was observed, offering a valuable metric for detecting brake wear emissions in subsequent studies conducted in the region. The EFs of carbonaceous matter, elements and ions generally varied by a factor 0.1 and 10 in comparison to literature values, while those for alkanes and polycyclic aromatic hydrocarbons were similar to the upper values previously reported. The average number size distribution was characterized by a single mode around 35 nm. The particles number EF (for diameters between 10 and 480 nm) was within the range of 1014-1015 particles per kg of fuel. The chemical mass balance model showed an average contribution to EF of 62% from non-exhaust sources. This study highlights the need for more enforceable stringent vehicular regulations because of the local practices (i.e., removal of catalyst) and some EF values are very high compared to other studies/countries.

Dermotoscope assisted diagnosis of adolescent bullous pilomatricoma: six case reports

BackgroundPilomatricoma (PM) is a cutaneous benign neoplasm derived from the hair matrix. It clinically presents as a solitary and firm nodule overlying normal epidermis and is usually not easy to be noticed at early stage. Nevertheless, when special bullous lesion occurs in a short time or even ulcerates, preoperative diagnosis by a dermatologist is often challenging especially when the pediatric patients refuse biopsy.Case presentationWe present six bullous PM cases and particularly conduct correlation analysis on the dermotoscopy and histopathology detection data. The basic information, medical history, symptoms and lesion morphology results of the patients were also provided. We found that the incidence of bullous PM was higher in females than in males, and most patients were adolescents and the predilection location seem to be consistent in the vaccine injection site. The dermatoscopic features of bullous PM reported were luminous yellow structure below, with gray-blue homogeneous areas and branched capillary. The histological features were consistent with PM, and evident epidermis bullae were above the tumor with extraordinary dilation of lymphangion in the upper dermis. The patients described in this study were Chinese patients in Han population included 4 females and 2 males, coincidentally, they are almost teen-age, respectively are 5,11,17,19,21,22 year-old.ConclusionsThis study reported and analyzed the dermotoscopy and clinical characteristics of bullous PM, dermotoscopy may guide as a rapid and reliable technique in bullous PM diagnosis.

Characterization of PM2.5 Carbonaceous Components in a Typical Industrial City in China under Continuous Mitigation Measures.

The goals of the "dual carbon" program in China are to implement a series of air pollution policies to reduce the emission of carbon-bearing particulate matter (PM). Following improvements in the reduction in carbon emissions in Handan City, China, fine particulate matter (PM2.5) was collected in the winters from 2016 to 2020 to characterize the concentrations and sources of carbonaceous components in PM2.5. Trend analysis revealed that both organic carbon (OC) and elemental carbon (EC) concentrations significantly decreased. The proportion of total carbon aerosol (TCA) in PM2.5 decreased by 47.0%, highlighting the effective reduction in carbon emissions. Secondary organic carbon (SOC) concentrations increased from 2016 (12.86 ± 14.10 μg·m-3) to 2018 (36.76 ± 21.59 μg·m-3) and then declined gradually. SOC/OC was larger than 67.0% from 2018 to 2020, implying that more effective synergistic emission reduction measures for carbonaceous aerosol and volatile organic compounds (VOCs) were needed. In the winters from 2016 to 2020, primary organic carbon (POC) concentrations reduced by 76.1% and 87.6% under a light/moderate pollution period (LP) and heavy/severe pollution periods (HPs), respectively. The TCA/PM2.5 showed a decreasing trend under LP and HP conditions, decreasing by 42.1% and 54.7%, respectively. Source analysis revealed that carbonaceous components were mainly from biomass burning, coal combustion and automotive exhaust emissions in the winters of 2016 and 2020. OC/EC and K+/EC analysis pointed out that air pollutant reduction measurements should focus on rectification biomass fuels in the next stage. Compared with 2016, the contributions of automotive exhaust emissions decreased in 2020. OC and EC concentrations decreased due to control measures on automotive exhaust emissions.

Characteristics of PM2.5 bounded carbonaceous aerosols, carbon dioxide and its stable carbon isotopes (δ13C) in rural households in northwest China: Effect of different fuel combustion

In order to fully understand the carbon emission from different fuels in rural villages of China, especially in the typical atmospheric pollution areas. The characteristics of carbonaceous aerosols and carbon dioxide (CO2) with its stable carbon isotope (δ13C) were investigated in six households, which two households used coal, two households used wood as well as two households used biogas and liquefied petroleum gas (LPG), from two rural villages in Fenwei Plain from March to April 2021. It showed that the fine particulate matter (PM2.5) emitted from biogas and LPG couldn't be as lower as expected in this area. However, the clean fuels could relatively reduce the emissions of organic carbon (OC) and element carbon (EC) in PM2.5 compare to the solid fuels. The pyrolyzed carbon (OP) accounted more total carbon (TC) in coal than the other fuels use households, indicating that more water-soluble OC existed, and it still had the highest secondary organic carbon (SOC) than the other fuels. Meantime, the coal combustions in the two villages had the highest CO2 concentration of 527.6 ppm and 1120.6 ppm, respectively, while the clean fuels could effectively reduce it. The average δ13C values (−26.9‰) was much lighter than almost all the outdoor monitoring and similar to the δ13C values for coal combustion and vehicle emission, showing that they might be the main contributors of the regional atmospheric aerosol in this area. During the sandstorm, the indoor PM2.5 mass and CO2 were increasing obviously. The indoor cancer risk of PAHs for adults and children were greater than 1 × 10−6, exert a potential carcinogenic risk to human of solid fuels combustion in rural northern China. It is important to continue concern the solid fuel combustion and its health impact in rural areas.

Effect of primary air and coal properties on the formation of fine mode particles during low NOx gasification-combustion of coal in a self-sustaining furnace

Gasification-combustion technology can reduce NOx while the formation characteristics of fine mode PM is unclear. This research studied the impact of the excess air coefficient (αg) of the gasifier and the properties of coal on the formation and evolution of fine mode PM. The experiment was conducted on a self-sustaining furnace consisting of a gasifier where pyrolysis/gasification occurs and a combustion chamber where burnout of gasification gas and char occurs. The results showed that fine mode PM and NOx can be synergistically reduced by optimizing αg during gasification-combustion. A low or high αg can lead to a high furnace temperature in the gasifier or combustion chamber, respectively. Elimination of high temperature is crucial to reduce element vaporization which promotes the formation of fine mode PM. Additionally, an optimized combination of furnace temperature and reducing atmosphere in the gasifier can decrease NOx. The optimal αg was 0.32 for bituminous coal (BC). Fine mode PM generated from gasification-combustion of BC, lean coal (LC), and semi-char (SC) mainly consists of Ca, Si, Fe, and S. The vaporization of element from LC and BC primarily occurs during char combustion in the combustion chamber, while the vaporization of element from SC occurs almost equally in the gasifier and combustion chamber.

A model for simulating PM2.5 concentration in subway systems

Due to adverse effects on health, the PM2.5 of subway systems is increasingly attracting people's attention. Although scholars have conducted many experimental studies on the characteristics of PM2.5 in subway stations, theoretical research on the propagation law of PM2.5 in subway systems is still lacking. In this study, we established a mathematical model for the PM2.5 concentration in the subway system based on the principle of mass conservation, including a PM2.5 generation model for trains operating in tunnels and a network model for calculating the ventilation rate, to simulate the variation of PM2.5 concentration in various areas of the subway system. The model was used to simulate the PM2.5 concentration of a subway line in Nanjing, China and on-site testing was conducted to verify the simulation results, with an error was within 10%. The simulation results quantitatively illustrate the influence of train density and ambient concentrations on PM2.5 variation in the subway system and the comparison with studies in other countries has also verified the applicability. This model could be used based on actual subway lines to simulate the PM2.5 concentration at any time during subway operation, thereby providing effective guidance for improving the environmental air quality of subway stations and optimizing the design of environmental control systems.

Breath of Danger: Unveiling PM2.5's Stealthy Impact on Cancer Risks.

This article explores the intricate relationship between airborne particulate matter (PM), specifically PM2.5, and its profound impact on human health, emphasising the heightened risks of cancer. Examining the composition and characteristics of PM2.5, such as particle size and surface area, reveals its ability to induce inflammatory injury and oxidative damage. The carcinogenic potential extends beyond respiratory implications, affecting various organs, including the digestive tract, breast, and prostate. In addition to the genotoxic effects of PM2.5, attached polycyclic aromatic hydrocarbons are recognized to be endocrine-disrupting chemicals with specific implications for breast and prostate cancer. Long-term exposure to PM2.5 is associated with increased cancer mortality, with specific risks identified for different cancer types. The linear correlation between cancer risk and PM2.5 concentration calls for a re-evaluation of permissible emission levels. The article concludes by proposing specific mitigating strategies for individuals exposed to elevated PM2.5. It suggests antioxidant-rich diets and supplements, and exploring inhalation-based antioxidant administration as potential protective measures.

Particulate matter emissions from light-duty gasoline vehicles under different ambient temperatures: Physical properties and chemical compositions

Fine particulate matter (PM2.5) from vehicle exhaust is typically emitted at breathing height and thus imposes severe adverse effects on human health and air quality. However, there is currently limited knowledge on the characteristics of PM2.5 in exhaust, specifically its chemical components, at different ambient temperatures. Particulate emissions from typical light-duty gasoline vehicles (LDGVs) were investigated on a chassis dynamometer according to the Worldwide Harmonized Light-Duty Test Cycle at ambient temperatures of 38 °C, 28 °C, 15 °C, 5 °C and − 7 °C. The results showed a significant increase in particulate mass (PM) and particle number (PN) emissions with decreasing ambient temperature, particularly during cold starts below 5 °C. The particle size distributions exhibited distinct bimodal patterns, with accumulation-mode (AM) particles (60–125 nm) dominating the gasoline direct injection (GDI) distribution and nucleation-mode (NM) particles (8–12 nm) dominating the port fuel injection (PFI) distribution. AM particles were more temperature-sensitive than NM particles. Lower temperatures produced higher emissions of elements, carbonaceous components, and large-ring polycyclic aromatic hydrocarbons, while water-soluble ions showed an opposite trend. The total toxic equivalent, primarily influenced by benzo[a]pyrene, was significantly higher at −7 °C. The penalty distribution of LDGV PM and PN, defined by comparing the emissions at the various temperatures to those at regulated temperatures (23–30 °C), exhibited notable temporal heterogeneity (winter > autumn > spring > summer) and spatial heterogeneity (northern China > southern China). These findings are essential for establishing more stringent vehicle emission standards and improving emission models in cold environments.

Characteristics of PM2.5 Chemical Species in 23 Chinese Cities Identified Using a Vehicular Platform

PM2.5 pollution remains a significant concern in China due to its adverse environmental and health implications. This study aims to explore in depth the differences in the causes of PM2.5 pollution between some regions in China based on high temporal resolution PM2.5 component information. We used a particulate matter chemical composition vehicle (PMCCV) as a mobile monitoring platform which travelled among 23 cities in China from March 2018 to December 2019 to collect PM2.5 concentrations and chemical composition data. Observations revealed that PM2.5 concentrations were notably higher in northern cities compared than their southern counterparts. Seasonal variation was evident, with peak concentrations during winter and troughs during summer. In regions experiencing severe winter pollution, such as Hebei and Shanxi (HB/SX), organic matter (OM) emerged as the dominant contributor (47.3%), escalating with increasing PM2.5 concentrations. OM significantly impacted PM2.5 levels during autumn in Jiangxi and Anhui (AH/JX) and across the monitoring period in Liuzhou, Guangxi (GX), with the former related to vehicle emissions and the latter related to bagasse reuse and biomass burning emissions. Conversely, nitrate (NO3−) made the highest contribution to PM2.5 during winter in the AH/JX region (34.4%), which was attributed to reduced SO2 levels and favorable low-temperature conditions conducive to nitrate condensation. Notably, nitrate contribution to HB/SX rose notably in heavily polluted winter conditions and during light–moderate pollution episodes in the autumn. Sulfate (SO42−) was dominant among PM2.5 components during summer in the study regions (29.9% in HB/SX, 36.1% in HN/SD, and 49.7% in AH/JX). Additionally, pollution incidents in Chuzhou, Anhui Province, and Baoding, Hebei Province, underscored nitrates and organic matter, respectively, as the primary causes of sharp PM2.5 increases. These incidents highlighted the influence of large emissions of primary aerosols, gaseous precursors, and stagnant meteorological conditions as pivotal factors driving haze pollution in the HB/SX region.

Health risk assessment and characterization of PM2.5 bound bioaerosols at the municipal solid waste landfill site of Nagpur, India

Landfill being the reservoir of organic waste, serves as the most important source in the generation and emission of bioaerosols in the environment, and these bioaerosols have a significant impact on the environment and public health. In India, there are limited studies on the characterization of culturable bacteria and fungi in the bioaerosols originating from landfills. Therefore, the present study aimed to quantify and identify the bioaerosols and study their characteristics at a landfill site in Nagpur, India. The study describes the seasonal variation of PM2.5, PM2.5-associated bacteria and fungi in the landfill air, their molecular identification, antibiotic resistance, pathogenicity, dispersion and health risk assessment during winter and pre-monsoon seasons at the landfill site and surrounding residential sites in upwind and downwind directions. The study showed PM2.5 concentration was highest in the winter season (265.56 μg/m3) followed by the pre-monsoon season (173.1 μg/m3) at the landfill site. The culturable bioaerosol level was also significantly higher in winter (11056 CFU/m3) in comparison to pre-monsoon season (2244 CFU/m3) at the landfill site. Upon isolating and characterizing the microorganisms in the bioaerosols, some of the bacterial isolates, like Bacillus, Staphylococcus gallinarum, and Streptomyces speibonae were found to be resistant to chloramphenicol, netillin, nitrofurantoin, streptomycin etc. About 30% of the bacterial isolates were found to show β-hemolytic virulence activity. This indicated the presence of multi-drug resistant and potentially pathogenic bacteria in the bioaerosols over the landfill. The health risk assessment in adults indicated that the workers at the landfill site were at risk of bacterial aerosol in the winter season (hazard quotient i.e., HQ>1). The impact of bioaerosols on children needs to be investigated in the further studies and regular monitoring of bioaerosols is suggested to avoid any morbidity. To the best of our knowledge, this is the first study on the characterization of microorganisms from the bioaerosols over an open landfill site in India.

Characteristics of PM2.5 in Long Binh Industry Park, Bien Hoa City, Vietnam: Mass Concentrations, Chemical Composition, Source Apportionment, and Health Risk Assessment

This study aimed to assess the concentration, source, chemical properties, and health risks associated with PM2.5 in Long Binh ward, Bien Hoa city, Dong Nai province, where there is a large distribution of industrial zones. PM2.5 samples were collected using a high-volume sampler during both the dry and rainy seasons. The mass concentration of PM2.5 was determined by Mettler Toledo XS205, and the chemical properties of eleven heavy metal elements were analyzed using inductively coupled plasma mass spectrometry (ICP-MS; iCAP-RQ, Thermo Science, US). The migration trajectory of PM2.5 was determined using the HYSPLIT model. The results showed that the PM2.5 concentration exceeded the WHO recommended value, while only the PM2.5 concentration in the dry season exceeded the national standard gia (QCVN 05:2013/BTNMT). Industry, road and non-road transportation activities were identified as the main sources of PM2.5. The heavy metal element Cr was found to be the most significant contributor to the chemical composition of fine particles. The health risk assessment revealed that the HI values were lower than 1 in both seasons, indicating a low risk of chronic adverse health effects. However, the TRC values exceeded the recommended threshold for cancer risk in both the rainy season (10-4 ± 6,6 x 10-5) and dry seasons (7,9 x 10-4 ± 5,6 x 10-4).

Frequent haze events associated with transport and stagnation over the corridor between the North China Plain and Yangtze River Delta

Abstract. PM2.5 pollution is a major air quality issue that deteriorates human health, and numerous studies have focused on PM2.5 pollution in major regions such as the North China Plain (NCP) and Yangtze River Delta (YRD). However, the characteristics of PM2.5 concentrations and the associated formation mechanism in the transport corridor (referred to as SWLY) between the NCP and YRD are largely ignored. Based on observational data, we find that the number of PM2.5 pollution events in SWLY is comparable to that in the NCP, far exceeding that in the YRD, which is indicative of the severity of air pollution in this area. Utilizing a regional climate and air quality model, we isolate the effect of seesaw transport events, e.g., transport between the NCP and YRD, and atmospheric stagnation on the accumulation of PM2.5 over SWLY. Specifically, seesaw events and stagnation, comparable to each other, collectively account for an average of 67 % of pollution days, with PM2.5 exceeding 75 µg m−3, and this fraction (85 %) is even larger for severe haze events, with PM2.5 exceeding 150 µg m−3. Furthermore, the connection between seesaw transport and large-scale circulation is examined. The transregional transport of pollutants from the NCP to the YRD (YRD to NCP) is likely stimulated by positive (negative) to negative (positive) geopotential height anomalies at 500 hPa located in northern China. The health effect due to short-term PM2.5 exposure induced by the transregional transport and stagnation is investigated, yielding a total of 8634 (95 % CI: 6023–11 223) and 9496 (95 % CI: 6552–12 413) premature deaths, respectively, in SWLY during winter 2014–2019, which is as high as 9 % of the total premature deaths in China, even though SWLY takes up less than 1 % of China's area. While atmospheric stagnation is in general projected to occur more frequently under a warming climate, this study indicates the importance of regional emission control to alleviate PM2.5 pollution from seesaw transport and stagnation.

Comparison and research on load characteristics of PM in different permanent magnet synchronous machines

PM enable PMSMs to have higher torque-density and power-density, however the machine performance is closely related to its load characteristics. When the armature excitation does not match the load characteristics of the PM and machine, it can lead to demagnetization and performance degradation. By comparing and studying the IPMSM’s and SPMSM’s load characteristics, a more reasonable machine topology of components such as PM can be obtained, and high-performance machines can be designed more efficiently. Based on the material characteristics of the PM, the armature reaction law of different machines and the demagnetization law of the PM at different current angles were analyzed. There are different magnetic field distribution patterns in IPMSM and SPMSM, and their different load characteristics are compared to study the methods for improving the anti-demagnetization ability of PMs based on different machine structures.

Geographical verification of Pleuropterus multiflorus thunb. by functional compounds, stable isotope ratios, and multielement combined with machine learning methods

The dry roots of Pleuropterus multiflorus Thunb. (PM) have been traditionally utilized as functional foods and medicines China and various Asian countries. They are extensively cultivated in multiple provinces in China, with variations in prices and qualities. This study aims to investigate the regional characteristics of PM by 4 stable isotope ratios, 40 multielement and 16 functional compounds contents, using a total of 357 samples from 8 different geographical origins. Machine learning methods were developed to authenticating the geographical origins of PM, yielding the accuracy range from 94.44 % to 100 % in the test set. Notably, the protected designation of origin, Deqing PM, exhibited a high accuracy of 100 % in most models, A total of 30 significant prediction variables, encompassing 16 functional compounds, δ2H, 12 rare earth elements, and Cu, were identified. Additionally, the study identified altitude, high temperature, and dry or moisture index as the primary influenced environmental factors.

Characteristics and health risk assessment of indoor and outdoor PM2.5 in a rural village, in Northeast of China: impact of coal and biomass burning.

Fine particulate matter (PM2.5) has health effects that may depend on its sources and chemical composition. In this study, characteristics of PM2.5 chemical composition and health risk assessment from Songyuan, China, were investigated during day and night in indoor and outdoor from February 4 to 19, 2021. Relative high concentrations of PM2.5 were obtained in indoor environment than outdoor, with 503.95 ± 209.62μg/m3 during the day and 357.52 ± 232.81μg/m3 at night for the indoor environment. Relatively high total carbon, organic carbons, elemental carbons, polycyclic aromatic hydrocarbons (PAHs), and oxygenated polycyclic aromatic hydrocarbons (OPAHs) were obtained in indoor environment. However, the average concentrations of PAHs were higher during night (73.57 ± 43.09ng/m3) in indoor and OPAHs during day (6.027 ± 2.960ng/m3) in outdoor. They had different I/O distributions of these compounds during day and night. Indeno(1,2,3-cd) pyrene was the dominant PAHs, and benzanthrone was the dominant OPAHs; this is different with the previous studies. The high indoor/outdoor ratios showed the indoor coal and biomass burning greatly affect the indoor pollutants. Average ILCR health risk assessment for PAHs was all higher than 10-6 for different age gender, suggesting there has potential cancer risk existed for populations living in the rural coal and biomass burning area Songyuan, China.

지리정보시스템과 통계기법을 이용한 고농도 미세먼지 오염특성 파악: 동남권과 남부권 우심지역 사례 연구

지리정보시스템과 통계기법을 이용한 고농도 미세먼지 오염특성 파악: 동남권과 남부권 우심지역 사례 연구

Characteristics of PM2.5-bound metals in Japan over six years: Spatial distribution, health risk, and source analysis

Air sampling campaigns were conducted at 100 survey sites across Japan from April 2014 to February 2020, and a comprehensive database of atmospheric particles was obtained. In this study, the characteristics of PM2.5 and 26 metals were investigated in depth. Spatially, the concentration of PM2.5 gradually increased from the northeast to the southwest of Japan. The pollution in Kitakyushu City was the most serious, reaching 19.8 μg m−3. As an important particle component, metals did not show obviously spatial variation in Japan, with a sum concentration of 0.4 μg m−3. Anthropogenic metals only accounted for about 8% of the total metals, but they could pose a serious threat to public health. For children, the non-carcinogenic risk and carcinogenic risk due to exposure to anthropogenic metals could not be neglected in Japan; the corresponding HI and CR values at 100 survey sites ranged from 2.7 to 15.0 and 4.1 × 10−5 to 3.4 × 10−4, respectively. Adults faced lower health risks than children, with HI values ranging from 0.2 to 2.0 and CR values ranging from 2.0 × 10−5 to 1.6 × 10−4. The integrated health risk assessment results showed that the coastal region of the Seto Inland Sea and the north Tohoku Region were the most heavily polluted areas of Japan; in this study, 20 survey sites were finally determined to be high-risk sites, among which pollution control for Niihama City, Kitakyushu City, Hachinohe City, and Shimonoseki City were of first priority. With further combination with a positive matrix factorization model, it can be known that these four cities mainly had five to seven metal sources, and their heavy pollution was mainly caused by ship emissions, industrial emissions, biomass burning, and coal combustion. Overall, our study comprehensively revealed the regional patterns of PM2.5-bound metal pollution across Japan, which can help in making cost-effective risk management policies with limited national/local budgets.

Uncertainty analysis–forecasting system based on decomposition–ensemble framework for PM2.5 concentration forecasting in China

AbstractPractical analysis and forecasting of PM2.5 concentrations is complex and challenging owing to the volatility and non‐stationarity of PM2.5 series. Most previous studies mainly focused on deterministic predictions, whereas the uncertainty in the prediction is not considered. In this study, a novel uncertainty analysis–forecasting system comprising distribution function analysis, intelligent deterministic prediction, and interval prediction is designed. Based on the characteristics of PM2.5 series, 16 hybrid models composed of various distribution functions and swarm optimization algorithms are selected to determine the exact PM2.5 distribution. Subsequently, a hybrid deterministic forecasting model based on a novel decomposition–ensemble framework is established for PM2.5 prediction. Regarding uncertainty analysis, interval prediction is established to provide uncertain information required for decision–making based on the optimal distribution functions and deterministic prediction results. PM2.5 concentration series obtained from three cities in China are used to conduct an empirical study. The empirical results show that the proposed system can achieve better prediction results than other comparable models as well as provide meaningful and practical quantification of future PM trends. Hence, the system can provide more constructive suggestions for government administrators and the public.