Characteristics Of Particulate Matter Research Articles

Personal level exposure and hazard potential of particulate matter during haze and non-haze periods in Singapore.

Severe haze episodes originating from biomass burning are common in Southeast Asia. However, there is a paucity of data on the personal exposure and characteristics of Particulate Matter (PM) present in ambient air during haze and non-haze periods. Aims of this study were to monitor 24h ambulatory exposure to PM among school children in Singapore; characterize haze and non-haze PM for their physicochemical properties, cytotoxicity and inflammatory potential, using bronchial epithelial cell culture model (BEAS-2B). Forty-six children had ambulatory PM exposure monitored using portable Aethalometer and their hourly activity recorded. The mean (±SE) PM exposure on a typical school day was 3343 (±174.4) ng/m3/min. Higher PM exposure was observed during haze periods and during commuting to and from the school. Characterization of PM collected showed a drastic increase in the proportion of ultrafine particle (UFP) in haze PM. These PM fraction showed higher level of sulphur, potassium and trace metals in comparison to those collected during non-haze periods. Dose dependent increases in abiotic reactive oxygen species generation, activation of NF-κB and cytotoxicity were observed for both haze and non-haze PM. Generally, haze PM induced significantly higher release of IL-6, IL-8 and TNFα by BEAS-2B cells in comparison to non-haze PM. In summary, this study provides experimental evidence for higher PM exposure during haze period which has the potential to elicit oxidative stress and pro-inflammatory cytokine release from airway epithelial cells.

Spectral and isotopic characteristics of particulate organic matter in a subtropical estuary under the influences of human disturbance

Abstract Particulate organic matter (POM) in the coastal zone plays an important role in global carbon cycle, yet its spectral properties under human disturbance are not well understood. This study investigated the source and dynamics of POM in a typical coastal area (Minjiang Estuary, China) under the influences of estuarine mixing, urbanization and dam construction, based on spectral and isotopic analysis. The yield of particulate organic carbon from the watershed (0.38 g m−2 yr−1) was in part limited by the historical decrease in sediment discharge downstream hydropower station. The absorption and fluorescence indices of POM suggested an important contribution from biological production with a low humic content. The importance of river and estuarine production was supported by elemental and isotopic analysis, in particular for N-bound constituents of POM. Three humic-like and two protein-like fluorescent components were identified from POM using fluorescence excitation-emission matrices-parallel factor analysis (EEMs-PARAFAC). They showed weak correlations with salinity, suggesting non-conservative behaviors of fluorescent POM during the estuarine mixing. Principal component analysis (PCA) identified two principal factors, which were related to the level of chromophoric POM (PC1) and biological production (PC2), respectively. The PCA results indicated stronger influence of biological production in the estuarine zone and potential effect of sediment re-suspension and/or wastewater discharge in the urban zone. Overall, our results demonstrated significant influences of human disturbance on the flux, source and dynamics of POM in the coastal zone, which could be assessed by spectral and stable isotopic analysis.

Understanding the effects of catalytic partial flow filters on particle removal efficiency

Abstract The combination of filtration and catalytic pollutant's removal within one aftertreatment component is investigated in this work. A catalytic partial flow filter as a particulate oxidation catalyst (POC) has been chosen for this study. The trapping and oxidation functions as well as its close-coupled position, which provides higher exhaust temperature profiles, can promote passive regeneration as a mean to limit the build-up of soot in the filter. This component is not intended as a replacement of the diesel particulate filter (DPF) in the exhaust system, but it can help reducing the frequency and/or duration of the DPF active regeneration, thus limiting the impact on fuel economy and CO2 emissions. The pollutant's oxidation activity, particulate filtration mechanisms and effect on particulate matter characteristics of the POC have been comprehensively researched under a wide range of engine operation conditions, varying by particle concentration, space velocity and temperature. The interactions between the DPF and the POC have been studied from the filtration and backpressure point of view. Long term filtration and catalytic performance as well as passive regeneration have been also studied. Results show that combining oxidation and filtration functions within a single unit helps to achieve greater catalytic pollutant removal capability and a significant particulate matter filtration efficiency, reducing the pressure increase across the DPF.

On-the-fly particle metrology in hollow-core photonic crystal fibre.

Efficient monitoring of airborne particulate matter (PM), especially particles with aerodynamic diameter less than 2.5 µm (PM2.5), is crucial for improving public health. Reliable information on the concentration, size distribution and chemical characteristics of PMs is key to evaluating air pollution and identifying its sources. Standard methods for PM2.5 characterization require sample collection from the atmosphere and post-analysis using sophisticated equipment in a laboratory environment, and are normally very time-consuming. Although optical methods based on analysis of scattering of free-space laser beams or evanescent fields are in principle suitable for real-time particle counting and sizing, lack of knowledge of the refractive index in these methods not only leads to inevitable sizing ambiguity but also prevents identification of the particle material. In the case of evanescent wave detection, the system lifetime is strongly limited by adhesion of particles to the surfaces. Here we report a novel technique for airborne particle metrology based on hollow-core photonic crystal fibre. It offers in situ particle counting, sizing and refractive index measurement with effectively unlimited device lifetime, and relies on optical forces that automatically capture airborne particles in front of the hollow core and propel them into the fibre. The resulting transmission drop, together with the time-of-flight of the particles passing through the fibre, provide unambiguous mapping of particle size and refractive index with high accuracy. The technique offers unique advantages over currently available real-time particle metrology systems, and can be directly applied to monitoring air pollution in the open atmosphere as well as precise particle characterization in a local environment such as a closed room or a reaction vessel.

Spatial Temporal Characteristics and Cluster Analysis of Chemical Components for Ambient PM2.5 in Wuhan

The characteristics of chemical components of particulate matter are good indicators for analyzing sources and causes of pollution. The spatial and temporal distribution characteristics of particulate matter can reflect regional pollution problems in urban development, providing a basic dataset to support effective control of particulate matter sources. We collected PM2.5 and analyzed its concentration and chemical components at eight sites during different seasons. The results indicated that the average concentration of PM2.5 in Wuhan reached 70.7 μg·m-3. The concentration of PM2.5 in winter (103.1 μg·m-3) was significantly higher than that of other seasons, and the lowest concentration was in autumn (52.4 μg·m-3). The concentrations of PM2.5 in Donghu Gaoxin, Zhuankou New Area, and Qingshan Ganghua Station were significantly higher than those at the other sites. The main chemical components in PM2.5 were OC and SO42-, accounting for 15.4% and 14.2%, respectively. The OC concentration was the highest in winter, whereas SO42-concentration was the highest in summer. The average annual OC/EC ratio was up to 2.80, lower in winter and spring, and higher in summer and autumn. Material reconstruction showed that secondary particles and organic matter (OM) were major substances, accounting for 32.34% and 20.44% of PM2.5 mass, respectively. Coal combustion and vehicle exhaust might be the main contributors to ambient PM2.5. The highest fractions for OM were at the Wujiashan and Donghu Gaoxin sites, whereas the fraction of secondary particles was higher at each site, suggesting that secondary pollution had obvious regional characteristics in Wuhan. Cluster analysis based on the characteristics of chemical components showed that the eight sites were divided into three clusters:1 Hanyang Yuehu, Haze, Donghu Liyuan, and Huangpi sites, where the main characteristics were that the concentrations of components at each point were low; ② Zhuankou New Area and Qingshan Ganghua, which were characterized by higher nitrogen components; and ③ Donghu Gaoxin and Wujiashan, where not only industrial sources were heavily polluted in Wuhan, but also motor vehicles and dust pollution greatly contributed.

Temporal and Spatial Distribution Characteristics of Atmospheric Particulate Matter (PM10 and PM2.5) in Changchun and Analysis of Its Influencing Factors

With Changchun’s economic development, atmospheric particulate pollution has become a significant challenge in Changchun. The spatiotemporal patterns of particulate matter emissions are an inherent characteristic for particulate matter emissions. By using hourly PM (particulate matter) mass concentration measured at 10 atmospheric automatic monitoring stations and meteorological parameters, the spatiotemporal distribution characteristics of particulate matter (PM10 and PM2.5) and its relationship with meteorological parameters of Changchun have been analyzed. Pollution pathways and source distribution were investigated using HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory) model and cluster analysis. Results indicated that the quarterly average PM2.5 and PM10 mass concentrations in Changchun were higher in the first quarter and the fourth quarter. PM concentrations observed in all seasons generally exhibited two peaks, at 07:00–10:00 and 21:00–23:00, with the exception of PM10 in spring. PM pollution was concentrated mainly in the central, northern, and western areas of Changchun in most seasons, mainly due to anthropogenic activities and soil dust transported outside the region. PM concentrations were negatively correlated with relative humidity and temperature. PM2.5 concentrations were negatively correlated with wind speed, while PM10 concentrations were positively correlated with wind speed. The results of backward trajectory clustered showed that the northwest airflow had the greatest impact on PM of Changchun, except summer.

Influence of alternative fuels on combustion and characteristics of particulate matter morphology in a compression ignition diesel engine

The improvement of combustion and harmful emissions reduction has been driven by multiple factors; alternative fuels can be one of the important factors. In this study, Gas-to-Liquid (GTL) and Ethanol-RME-Diesel blend are used as an alternative fuels in a single cylinder diesel engine. The impact of alternative fuel on particulate matter (PM) characteristics and gaseous emissions were studied. These results reveal that ethanol blend increases the in-cylinder pressure and rate of heat release (ROHR) compared to the GTL and diesel fuel by 4% and 13% respectively. The particulate size distribution (PSD) was smaller from the combustion of ethanol blend compared to diesel and GTL fuel. The experimental results indicated that the ethanol blend produces smaller size of soot agglomerate and lower number of soot primary particles (npo) than to the rest of fuel. Furthermore, it can be observed that the soot particles emitted from ethanol blend has less spherical shape due to smaller fractal dimension (Df) than to the diesel and GTL fuel. It is found that the NOX emissions were lower from the combustion of GTL fuel than ethanol blend and diesel fuel.

Emission Characteristics of Exhaust PM and Its Carbonaceous Components from China Ⅲ to China Ⅳ Diesel Vehicles in Shenyang

Diesel vehicles were the primary source of atmospheric particulate matter (PM) emitted by motor vehicles. To study the emission factors and carbon components of PM2.5 and PM10 from diesel vehicles in Shenyang, exhaust PM samples were collected from 15 diesel vehicles including small, medium, and large passenger vehicles, and light, medium, and heavy-duty trucks under China Ⅲ and China Ⅳ emission standards. This was undertaken using a dilution channel sampling system, and the carbon components were also analyzed. The results showed that the average distance-based PM2.5 and PM10 emission factors for diesel vehicles under China Ⅲ were (0.193±0.092) g·km-1 and (0.338±0.305) g·km-1, respectively, and for China Ⅳ were (0.085±0.038) g·km-1 and (0.100±0.042) g·km-1, respectively. This shows that the PM emission factors decreased significantly with the improvement of emission standards. Under the same emission standards, emission factors increased with the increase of vehicle passenger volume or cargo capacity. TC (total carbon) was the main component of the emissions from diesel vehicles. The mass fraction of TC under China Ⅳ (23%-48%) was significantly lower than under China Ⅲ (29%-70%). The mass fraction of elemental carbon (EC) for all types of diesel vehicles was greater than organic carbon (OC). The OC/EC value was 0.70±0.29, and the OC/EC value for diesel vehicles under China Ⅳ was lower than under China Ⅲ. The total mileage of passenger vehicles was significantly higher than that of trucks, resulting in higher fuel consumption. The mass fraction of OC and EC in passenger vehicles was higher than for trucks under the same emission standards. EC2 (elemental carbon which was measured at temperatures of 700℃) was the highest carbon content of diesel vehicles under China Ⅲ and China Ⅳ emission standards, which can be used in the identification of diesel vehicles in source apportionment studies.

Pollution Characteristics of Ambient Fine Particulate Matters at Mt. Halla-1100 and Gosan Sites in Jeju Island

Ambient fine particulate matters of PM10 and PM2.5 were collected at the Mt. Halla-1100 site (a site at an altitude of 1100 meters on Mt. Halla) and the Gosan site, which comprise a typical mountainous site and coastal background site, respectively, on Jeju Island. The major water-soluble ionic species of these sites were analyzed. The average mass concentrations of PM10 and PM2.5 at the Mt. Halla-1100 site were 0.59 times lower and 0.78 times lower, respectively, than those at the Gosan site. The composition ratios of the major secondary air pollutants (nss-SO42-, NO3-, and NH4+) of PM10 and PM2.5 were 86.2% and 93.2%, respectively, at the Mt. Halla-1100 site, while those at the Gosan site were 67.7% and 87.2%, respectively. These results show the comparatively larger contributions at the Mt. Halla-1100 site. The principal component analysis reveals that the main affecting factors for the ionic compositions of PM10 and PM2.5 particles at both sites are the anthropogenic emission sources, especially the comparative influence of organic acids at the Mt. Halla-1100 site, and the marine sources at the Gosan site. Based on the neutralization factors, the fine particulate matters were acidified mainly by sulfuric and nitric acids, and the neutralization was relatively caused by calcium carbonate in PM10 particles and ammonia in PM2.5 particles. The clustered back trajectory analyses indicated that the major ionic concentrations of PM10 and PM2.5 comparatively increased when the airflow moved from continental China and the Korean Peninsula. The polluting influence from China was apparent in the upper planetary boundary layer (PBL) compared with that at ground level. Key Words: PM10, PM2.5, Mt. Halla-1100 site, Gosan site, Planetary Boundary Layer (PBL)

Emission characteristics of fine particulate matter from ultra-low emission power plants

As one of the highest energy consuming and polluting industries, the power generation industry is an important source of particulate matter emissions. Recently, implementation of ultra-low emission technology has changed the emission characteristic of fine particulate matter (PM2.5). In this study, PM2.5 emitted from four typical power plants in China was sampled using a dilution channel sampling system, and analyzed for elements, water-soluble ions and carbonaceous fractions. The results showed that PM2.5 concentrations emitted from the four power plants were 0.78 ± 0.16, 0.63 ± 0.09, 0.29 ± 0.07 and 0.28 ± 0.01 mg m−3, respectively. Emission factors were 0.004–0.005 g/kg coal, nearly 1–2 orders of magnitude lower than those reported in previous studies. The highest proportions of PM2.5 consisted of organic carbon (OC), SO42−, elemental carbon (EC), NH4+, Al and Cl−. Coefficients of divergence (CDs) were in the ranges 0.22–0.41 (for an individual plant), 0.43–0.69 (among different plants), and 0.60–0.99 (in previous studies). The results indicated that the source profiles of each tested power plant were relatively similar, but differed from those in previous studies. Enrichment factors showed elevated Se and Hg, in accordance with the source markers Se and As. Comparing source profiles with previous studies, the proportion of OC, EC and NH4+ were higher, while the proportion of Al in PM2.5 were relatively lower. The OC/EC ratio became concentrated at ∼5. Results from this study can be used for source apportionment and emission inventory calculations after implementation of ultra-low emission technologies.

Image correlation method to simulate physical characteristic of particulate matter

In the modern era, quality of air impacts a lot on human health and on climate change. This change in trend develops an interest for researchers to work on techniques which deal with the monitoring of air quality. This paper, for the first time, applies digital image correlation method to identify the velocity of particulate matter in digital images. Velocity of flowing particles in the atmosphere is a crucial factor of their physical characteristics as fast moving particles effects lot on human health as well as on environmental change. The unique particulate characterization process involves image analysis, preprocessing, calibration, feature extraction and representation. Among all these phases, feature extraction by the digital image correlation method is the key for precisely measuring the velocity of particulate matter present in digital images. Simulated model was found to measure accurate flow of particulate matter in various digital images.

Characteristics of Fine Particulate Matter and Polycyclic Aromatic Hydrocarbons Emitted from Coal Combustion Processes

Characteristics and emission factors of condensable particulate matter (CPM) and filterable particulate matter (FPM2.5) and polycyclic aromatic hydrocarbons (PAHs) (16 U.S. EPA PAHs and 15 + 1 EU P...

Compositional Characteristics of Fluvial Particulate Organic Matter Exported From the World's Largest Alpine Wetland

AbstractWetlands are hot spots for particulate organic matter (POM) supply into rivers, which link the land‐ocean transfer in the global carbon cycle. However, the source, composition, and seasonal variability of POM carried by wetland‐draining rivers are poorly constrained. Here we combine bulk and source‐specific biomarker analyses to investigate the fluvial POM biogeochemistry of the Black and White Rivers draining from the Zoige wetland. We find that POM was dominated by terrestrial organic matter including high‐molecular‐weight (HMW) lipids, branched glycerol dialkyl glycerol tetraethers, and lignin phenols. However, fluvial POM was rich in HMW lipids and poor in lignin phenols compared to the catchment soils, possibly due to hydrodynamic sorting and dissolution processes. While lignin phenol concentrations were higher in the wet season, HMW lipid concentrations were lower. Additionally, lignin phenols increased with total suspended solids, while HMW lipids decrease. These contrasts imply an enhanced input of lignin‐rich particles from soil surface layers in the wet season, diluting HMW lipids. Compared with that in other rivers around the world with a higher forest coverage in the catchment, POM in the Black and White Rivers draining grass‐dominated wetlands had a much higher ratio of HMW fatty acids to lignin phenols. Our results represent a benchmark study highlighting compositional characteristics of fluvial POM exported from the Zoige wetland and the divergent behavior of molecular components during fluvial transfer. Such information is vital for assessing future changes in the Zoige wetland, given its high vulnerability to climatic and land use changes.

Analysis of Radiative Transfer Equation for Measurement of Particulate Matter Emitted from Coal-Fired Power Plants

Objectives This study represents the analysis of radiative transfer equation (RTE) for measurement of particulate matter emitted from coal-fired power plants. Generally, the light extinction method is used to measure the mass concentration of particulate matter. Methods In this paper, the two-flux approximation is used to solve the radiative transfer equation and obtain the nondimensional incident radiation within emission outlet. Also, the radiation characteristics of the particulate matter are predicted with Lorenz-Mie theory. The particulate matter has three size distributions with geometric mean particle diameters 10 nm, 100 nm and 1 µm. Results and Discussion Absorption and scattering cross-sections and asymmetric factor are predicted as a function of wavelength and compared with respect to geometric mean particle diameters. Also, mass absorption and scattering cross-sections are predicted for conversion of particulate matter mass concentration. The nondimensional incident radiations at the emission outlet are calculated and compared with that of Beer-Lambert law for mass concentration 10 mg/m3 and 50 mg/m3. Conclusions Beer-Lambert law is valid for low scattering medium compared with absorption of medium. Nondimensional incident radiations at the emission are highly affected by the radiation characteristics of particulate matter. Key words: Particulate matter, Light scattering, Light extinction, Radiative transfer equation, Radiation characteristics

Characteristics of Fine Particulate Matter (PM2.5) over Urban, Suburban, and Rural Areas of Hong Kong

In urban areas, fine particulate matter (PM2.5) associated with local vehicle emissions can cause respiratory and cardiorespiratory disease and increased mortality rates, but less so in rural areas. However, Hong Kong may be a special case, since the whole territory often suffers from regional haze from nearby mainland China, as well as local sources. Therefore, to understand which areas of Hong Kong may be affected by damaging levels of fine particulates, PM2.5 data were obtained from March 2005 to February 2009 for urban, suburban, and rural air quality monitoring stations; namely Central (city area, commercial area, and urban populated area), Tsuen Wan (city area, commercial area, urban populated, and residential area), Tung Chung (suburban and residential area), Yuen Long (urban and residential area), and Tap Mun (remote rural area). To evaluate the relative contributions of regional and local pollution sources, the study aimed to test the influence of weather conditions on PM2.5 concentrations. Thus, meteorological parameters including temperature, relative humidity, wind speed, and wind directions were obtained from the Hong Kong Observatory. The results showed that Hong Kong’s air quality is mainly affected by regional aerosol emissions, either transported from the land or ocean, as similar patterns of variations in PM2.5 concentrations were observed over urban, suburban, and rural areas of Hong Kong. Only slightly higher PM2.5 concentrations were observed over urban sites, such as Central, compared to suburban and rural sites, which could be attributed to local automobile emissions. Results showed that meteorological parameters have the potential to explain 80% of the variability in daily mean PM2.5 concentrations—at Yuen Long, 77% at Tung Chung, 72% at Central, 71% at Tsuen Wan, and 67% at Tap Mun, during the spring to summer part of the year. The results provide not only a better understanding of the impact of regional long-distance transport of air pollutants on Hong Kong’s air quality but also a reference for future regional-scale collaboration on air quality management.

Characteristics of Heavy Particulate Matter Pollution Events Over Hong Kong and Their Relationships With Vertical Wind Profiles Using High‐Time‐Resolution Doppler Lidar Measurements

AbstractPrevious studies have reported boundary layer features related to air pollution. However, few studies have comprehensively evaluated the characteristics and mechanisms of vertical wind in the formation and evolution of heavy particulate matter pollution episodes (EP) in Hong Kong. In this study, we analyzed the vertical characteristics of heavy particulate matter (PM) pollutions over Hong Kong and their relationships with vertical wind profiles using high‐time‐resolution Doppler lidar measurements and hourly meteorological and air quality observations. We identified nine EPs and show that the events were closely coupled to various vertical wind profiles in the planetary boundary layer (PBL). Our analysis suggests that strong vertical wind speed with wind shear at certain heights in the PBL had a positive correlation with surface PM during most superregional transboundary EPs. The maximum transport height extends from the surface to about 2.0 km or even higher; these transport heights differed among superregional and regional transboundary EPs. At peak surface pollution concentrations during the nine EPs, the surface PM10 had a significant negative correlation with PBL heights/mixing layer heights, while the averaged wind shear in the PBL was significantly positively correlated. These EPs with different mixing layer heights were mainly driven by different vertical wind shear conditions under various weather systems related to surface high pressure, cold fronts, dust storms, and typhoons. This work provides scientific evidence that surface PM pollutions were closely related to the characteristics of vertical profiles during the transboundary air pollutions.

Vehicular Particulate Matter (PM) Characteristics Impact Vascular Outcomes Following Inhalation.

Roadside proximity and exposure to mixed vehicular emissions (MVE) have been linked to adverse pulmonary and vascular outcomes. However, because of the complex nature of the contribution of particulate matter (PM) versus gases, it is difficult to decipher the precise causative factors regarding PM and the copollutant gaseous fraction. To this end, C57BL/6 and apolipoprotein E knockout mice (ApoE-/-) were exposed to either filtered air (FA), fine particulate (FP), FP+gases (FP+G), ultrafine particulate (UFP), or UFP+gases (UFP+G). Two different timeframes were employed: 1-day (acute) or 30-day (subchronic) exposures. Examined biological endpoints included aortic vasoreactivity, aortic lesion quantification, and aortic mRNA expression. Impairments in vasorelaxation were observed following acute exposure to FP+G in C57BL/6 animals and FP, UFP, and UFP+G in ApoE-/- animals. These effects were completely abrogated or markedly reduced following subchronic exposure. Aortic lesion quantification in ApoE-/- animals indicated a significant increase in atheroma size in the UFP-, FP-, and FP+G-exposed groups. Additionally, ApoE-/- mice demonstrated a significant fold increase in TNFα expression following FP+G exposure and ET-1 following UFP exposure. Interestingly, C57BL/6 aortic gene expression varied widely across exposure groups. TNFα decreased significantly following FP exposure and CCL-5 decreased in the UFP-, FP-, and FP+G-exposed groups. Conversely, ET-1, CCL-2, and CXCL-1 were all significantly upregulated in the FP+G group. These findings suggest that gas-particle interactions may play a role in vascular toxicity, but the contribution of surface area is not clear.

Characteristics of biological particulate matters at urban and rural sites in the North China Plain

Depending on their concentrations, sizes, and types, particulate matters of biological origins (bioPM) significantly affect human health. However, for different air environments, they are not well characterized and can vary considerably. As an example, we investigated the bioPM differences at an urban (Beijing) site and a rural (Wangdu) site in the North China Plain (NCP) using an online monitoring instrument, an ultraviolet aerodynamic particle sizer (UV-APS), the limulus amebocyte lysate (LAL) assay, and a high-throughput sequencing method. Generally, lower concentrations of viable bioPM (hourly mean: 1.3 × 103 ± 1.6 × 103 m−3) and endotoxin (0.66 ± 0.16 EU/m3) in Beijing were observed compared to viable bioPM (0.79 × 105 ± 1.4 × 105 m−3) and endotoxin (15.1 ± 23.96 EU/m3) at the Wangdu site. The percentage of viable bioPM number concentration in the total PM was 3.1% in Beijing and 6.4% in Wangdu. Approximately 80% of viable bioPM was found to be in the range from 1 to 2.5 μm. Nevertheless, the size distribution patterns for viable bioPM at the Beijing and Wangdu sites differed and were affected by PM pollution, leading to distinct lung deposition profiles. Moreover, the distinct diurnal variations in viable bioPM on clean days were dimmed by the PM pollution at both sites. Distinct bacterial community structures were found in the air from the Beijing and Wangdu sites. The bacterial community in urban Beijing was dominated by genus Lactococcus (49.5%) and Pseudomonas (15.1%), while the rural Wangdu site was dominated by Enterococcus (65%) and Paenibacillus (10%). Human-derived genera, including Myroides, Streptococcus, Propionibacterium, Dietzia, Helcococcus, and Facklamia, were higher in Beijing, suggesting bacterial emission from humans in the urban air environment. Our results show that different air harbors different biological species, and people residing in different environments thus could have very different biological particle exposure.

The difference in effect of ambient particles on mortality between days with and without yellow dust events: Using a larger dataset in Seoul, Korea from 1998 to 2015.

Yellow Dust (YD) is a natural source of particulate matter (PM) in Korea. It remarkably increases the concentration of PM. However, characteristics of PM in YD period are different from those of PM in non-YD period. To investigate whether the association of PM with mortality is different between all days and non-YD days in Seoul, Korea, 1998-2015. We applied time-stratified case-crossover design to estimate effects of PM10 and PM2.5 on non-accidental cardiovascular and respiratory mortality. Effect estimates of PM were compared for all days in the study period and days without YD events. To identify whether different effect estimates between all days and non-YD days were not merely caused by the exclusion of high PM concentrations but rather by YD itself, we estimated effects of PM by randomly excluding the same number of days as days of YD. A total of 4,509,392 deaths were observed during the study period. A 10 μg/m3 increase in PM10 or PM2.5 was associated with a 0.15% (95% CI: 0.06% to 0.24%) or 0.27% (95% CI: 0.07% to 0.47%) increase in risk of non-accidental mortality for all days, respectively. These associations were changed to 0.30% (95% CI: 0.18% to 0.42%) and 0.33% (95% CI: 0.10% to 0.55%) when YD days were excluded from analyses. We also found that effect estimates of PM were larger when YD days were excluded than those when high PM concentrations were randomly excluded. The effect estimates of PM differed between all days and non-YD days. Our study suggests that including YD days in the analyses is likely to attenuate the effect of PM in a usual urban environment.

Effect of Coke Powder Ratio on Particle Emission and Sinter Quality in Sintering Process

Starting from the perspective of source reduction, the emission characteristics of particulate matters in sintering flue gas and sinter quality were studied by a sintering cup based on the fixed carbon 3.6% conditions in sintering raw materials. The particles were sampled by an Andersen 8-stage impactor at the coke powder ratios at 100%, 75%, 50% and 0%. The results showed that the particles in the sintering flue gas were mainly fine particles below 2.63 μm. When the coke powder ratio was 100%, the removal efficiency reached the maximum value of 34.37%. The effects of coke powder ratio on the sinter index were reflected in: when the coke powder ratio reduces, (1) the sintering speed decreases; (2) the solid fuel consumption increases; (3) the drum index improves. Compared with comprehensive indicators, the 100% coke powder was the most conducive condition to the production of enterprise sintering process.