Particulate Matter Generation Research Articles

Synergistic approaches to elevate indoor air quality: A holistic examination of classroom refinement, air exchange optimization, and flooring material impact

This research endeavors to elevate indoor air quality within aging school environments by concentrating on refining interior finishing materials and windows. Renovations, encompassing window and floor remodeling in classrooms, aim to mitigate particulate matter (PM) infiltration and enhance air exchange rates. Utilizing SPS30 sensors for the analysis of 0.3–2.5 μm particles, with a focus on their implications for human health, the study evaluated air exchange rates, deposition rates, infiltration rates, and particle generation during classroom activities. Post-renovation results demonstrated a noteworthy decrease in air exchange rates, indicating an enhancement in airtightness. The investigation delves into particle generation with various flooring materials, accentuating the importance of opting for durable and low-particle-generating alternatives. Health risk assessments, considering multiple exposure routes (inhalation, dermal contact, and ingestion), revealed reduced risks post-renovation, particularly for children. To further optimize indoor air quality, the study suggests the implementation of air purification systems. Examination of PM generation during student activities showcased a substantial reduction post-renovation. This study underscores the positive influence of architectural enhancements on indoor air quality while acknowledging the necessity for holistic solutions and continuous research.

Experimental study on particulate matter emissions in a lab-scale pressurized reactor

Pressurized oxy-combustion (POC) is a promising carbon capture and storage (CCS) technology to improve the process efficiency and economics as compared with first-generation oxy-combustion. However, compared with traditional air combustion, pollutant emissions would be significantly changed in pressurized conditions, and the sampling method has always been disputed. A novel particulate matter (PM) sampling system, consisting of a pressurized PM10 cyclone, a three-stage aerosol dilution system, and a depressurization device was developed to investigate PM emissions at elevated pressure. After being depressurized, PM10 size distribution in the flue gas was measured by using an Electrical Low-Pressure Impactor plus (ELPI+). The PM losses in three depressurization devices were evaluated. Results show that, compared to a needle or ball valve as a pressure regulator, the designed nozzle performed better in terms of controlling system pressure and reducing PM loss in the channel. The sampling system was then used to evaluate the effect of pressure on PM formation. At pressure, there is a greater production of PM below 30 nm, while the generation of coarse mode PM is reduced. Sulfur-based compounds in the combusting particles are prone to be evaporated into the gas phase at higher pressure, which contributes to the formation of fine mode PM, while Fe, Si, and Ca are reduced significantly. The coarse mode PM is reduced at higher pressure, which is mainly due to the weak fragmentation; as a result, more PM is captured in the PM10 cyclone. Compared with O2-N2 conditions, the O2-CO2 conditions can promote the formation of the fine mode PM.

Bedding Management for Suppressing Particulate Matter in Cage-Free Hen Houses

Cage-free (CF) layer houses tend to have high particulate matter (PM) levels because of bedding/litter floor and the birds’ activities, such as perching, dustbathing, and foraging on it. It has been reported that optimizing bedding management can potentially suppress PM levels in CF houses. The objectives of this study were to (1) test the effect of the top application of new bedding materials (BMs) on PM levels and (2) compare different BM PM reduction efficiencies. Small flake shavings (SFS), large flake shavings (LFS), and aspen wood chips (AWC) were top-dressed on the surface of the original litter (33-week-old litter) evenly in each of the BM treatment rooms at 20% volume of the original litter floor. The initial litter depths in the control, SFS, LFS, and AWC rooms were 4.6 ± 0.6, 4.8 ± 0.8 cm, 4.8 ± 0.8 cm, and 4.6 ± 0.9 cm, respectively. One room was used as a control without adding new BM. The results indicate that the top application of new bedding suppressed PM levels in all treatment rooms (p < 0.01). The PM2.5 reductions in the SFS, AWC, and LFS treatment rooms were 36.5%, 34.6%, and 28.9% greater than in the control room, respectively. The mitigation efficiencies were different between PM sizes. For instance, PM2.5, PM10, and TSP in the SFS room were lower than in the control room by 36.5%, 39.4%, and 38.7%, respectively. For litter quality, the moisture content was 18.0 ± 2.8, 20.0 ± 3.1, 20.6 ± 2.4, and 19.7 ± 4.2% in the control, SFS, LFS, and AWC rooms, respectively. Treatment rooms with 20% new BM had 10% higher litter moisture than the control room. The findings of this study reveal that the top application of new bedding on old litter is a potential strategy for reducing PM generation in CF houses. Further studies are warranted, such as regarding the effect of different ratios of new bedding on PM reduction, cost analysis, and verification tests in commercial CF houses.

Three-Dimensional Numerical Modeling and Analysis for the Municipal Solid-Waste Incineration of the Grate Furnace for Particulate-Matter Generation

A 3D numerical model of the municipal solid waste incineration (MSWI) process was constructed based on a grate furnace with a daily processing capacity of 800 tons. Fluent was used for analyzing key factors affecting the concentration and diffusion level of particulate matter (PM). According to the actual MSWI plant working condition, a 3D model of the incinerator and the waste heat boiler has been constructed under benchmarks. Key factors affecting PM generation were determined by combining mechanistic knowledge and experts’ experience. They were the combustion temperature of solid phase municipal solid waste (MSW), the wall’s PM collision mode, and the second baffle length. Subsequently, the process of resolving the 3D numerical model was delineated. Then, a univariate analysis of the aforementioned 3D model was conducted for the three pivotal factors mentioned above. Conclusively, the effect of the important factors on the number of particles at the outflow of the incinerator was analyzed via orthogonal experiments to obtain the optimal combination. PM concentration initially diminished and then rose with the increased combustion temperature of the solid-phase MSW. Furthermore, a noteworthy reduction in PM concentration was observed when the second baffle length was 12.45–12.95 m. The greatest influence on the PM concentration of the outlet was posed by the wall’s PM collision mode, followed by the second baffle length. The appropriate adjustment of the combustion temperature of the solid-phase MSW, selection of wall materials, and design of the second baffle length were beneficial for diminishing PM concentration and ensuring long-term stable operation of the MSWI process. The combinative optimality of the three key factors was acquired via orthogonal experiments, which proved the subsequent optimal control of PM concentration at the outlet.

Synergistic promotion of particulate matter reduction and production performance via adjusting electrochemical reactions in the zinc electrolysis industry

Heavy particulate matter (PM) pollution and high energy consumption are the bottlenecks of hydrometallurgy, especially in the electrolysis process. Therefore, an urgent need is to explore PM reduction methods with production performance co-benefits. This study presents three PM reduction methods based on controlling operating parameters, i.e., lowering electrolyte temperature, H2SO4 concentration, and current density of the cathode. The optimized conditions were also investigated using the response surface methodology to balance the PM reduction effect and Zn production. The results showed that lowering electrolyte temperature is the most efficient, with an 89.0% reduction in the PM generation flux (GFPM). Reducing H2SO4 concentration led to the minimum side effects on the current efficiency of Zn deposition (CEZn) or power consumption (PC). With the premise of non-deteriorating CEZn and PC, GFPM can be reduced by 86.3% at the optimal condition (electrolyte temperature = 295 K, H2SO4 = 110 g/L, current density = 373 A/m2). In addition, the reduction mechanism was elucidated by comprehensively analyzing bubble characteristics, electrochemical reactions, and surface tension. Results showed that lower electrolyte temperature inhibited the oxygen evolution reaction (OER) and compressed gas volume. Lower H2SO4 concentration inhibited the hydrogen evolution reaction (HER) and reduced electrolyte surface tension. Lower current density inhibited both OER and HER by decreasing the reaction current. The inhibited gas evolutions reduced the microbubbles’ number and size, thereby reducing GFPM. These results may provide energy-efficient PM reduction methods and theoretical hints of exploring cleaner PM reduction approaches for industrial electrolysis.

Temporal Variations of Air Quality in Cage-Free Experimental Pullet Houses

The welfare of laying hens in conventional caged houses has become an increased public concern, leading primary food chains, restaurants, and grocers in the United States to pledge to source only cage-free (CF) eggs by 2025 or 2030. Cage-free housing systems have been considered as a more humane alternative; however, they still come with certain challenges. One of the primary challenges with CF housing is the poor indoor air quality due to the high levels of ammonia (NH3) and particulate matter (PM). Despite the importance of air quality in animal welfare, most studies have focused on the egg-laying stage, thereby leaving a significant knowledge gap in the pullet phase. Addressing this gap is essential to ensure the well-being of laying hens in CF housing and to help producers and researchers identify effective strategies to mitigate the impact of poor indoor air quality on the bird’s health and welfare. Therefore, the objective of this study was to (a) examine the effect of the pullets’ age on NH3 and PM levels, and (b) find the effect of housing, litter moisture content (LMC), and relative humidity (RH) on air pollutant concentrations. The results show that the PM levels of PM2.5, PM10, and total suspended particles (TSP) increased significantly with the growth of birds from 1 to 16 weeks of age (WOA) (p < 0.01). For instance, PM2.5, PM10, and TSP levels were measured at 0.023 ± 0.003, 0.031 ± 0.004, and 0.058 ± 0.013 mg m−3 in the first week, and these levels increased to 1.44 ± 0.58, 2.723 ± 1.094, and 6.39 ± 2.96 mg m−3, respectively, by 16 WOA. In addition, PM levels measured near the perch were found to be three times higher than other locations inside the rooms (e.g., between the feeder and drinker or near the exhaust fan) (p < 0.01), as perching is one of the primary reasons for dust generation. Furthermore, a significant interaction between the age of the pullets and PM levels was found (p < 0.01), as the litter quality and the behaviors of birds were changing over time. For NH3 levels, average daily concentrations were lower than 1 ppm at 16 WOA for all rooms due to dry litter conditions (i.e., 9–10% LMC). Additionally, RH has been shown to have a significant effect on air pollutant concentration. Overall, the results indicate that the bird’s age significantly affects PM generation and PM variation within the rooms. The variation of PM was directly affected by RH inside the house. Therefore, this research will provide valuable information for both researchers and producers to control air pollutant emissions from the pullet stage in CF housing to ultimately improve the health and welfare of hens.

Cooking Particulate Matter: A Systematic Review on Nanoparticle Exposure in the Indoor Cooking Environment

Background: Cooking and fuel combustion in the indoor environment are major sources of respirable suspended particulate matter (RSPM), which is an excellent carrier of potentially harmful absorbed inorganic and organic compounds. Chronic exposure to RSPM can lead to acute pulmonary illness, asthma, cardiovascular disease, and lung cancer in people involved in cooking. Despite this, questions remain about the harmfulness of different particulate matter (PM) sources generated during cooking, and the factors influencing PM physico-chemical properties. The most reliable methods for sampling and analyzing cooking emissions remain only partially understood. Objectives: This review aims to comprehensively assess the risks of PM generated during cooking, considering the main sources of PM, PM chemical composition, and strategies for PM physico-chemical analysis. We present the first systematic analysis of PM sources and chemical composition related to cooking. We highlight significant differences between studies using different experimental conditions, with a lack of a standard methodology. Methods: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement rules and the Patient, Intervention, Comparison, and Outcome (PICO) strategy for scientific research, three different scientific databases (PubMed, Scopus, and Web of Science) were screened to find scientific articles that measure, collect, and analyze the chemical composition of nanometer- and micrometer-sized PM generated during cooking activities under different conditions. Data are summarized to assess risk, evaluating the main sources and factors influencing PM generation, their chemical composition, and how they have been collected and analyzed in changing experimental conditions. Results: From 2474 search results, there were 55 studies that met our criteria. Overall, the main variable sources of PM in cooking activities relate to the stove and fuel type. The concentration and chemical–physical properties of PM are also strongly influenced by the food and food additive type, food processing type, cooking duration, temperature, and utensils. The most important factor influencing indoor PM concentration is ventilation. The PM generated during cooking activities is composed mainly of elemental carbon (EC) and its derivatives, and the porous structure of PM with high surface-to-volume ratio is a perfect carrier of inorganic and organic matter. Conclusions: This review reveals a growing interest in PM exposure during cooking activities and highlights significant variability in the chemical–physical properties of particles, and thus variable exposure risks. Precise risk characterization improves possible preventive strategies to reduce the risk of indoor pollutant exposure. However, comprehensive PM analysis needs proper sampling and analysis methods which consider all factors influencing the physico-chemical properties of PM in an additive and synergistic way. Our analysis highlights the need for method standardization in PM environmental analyses, to ensure accuracy and allow deeper comparisons between future studies.

Advanced Strategies for Mitigating Particulate Matter Generations in Poultry Houses

Poultry farming plays a key role in agricultural air emissions. Particulate matter (PM) level tends to be high in broiler and cage-free layer houses, that may impair health and welfare of animals and their caretakers. To protect public health and welfare, the occupational exposure limit for PM10 and PM2.5 (i.e., PM diameters that are generally ≤10 and 2.5 μm, respectively) are suggested not to exceed 150 µg m−3 and 35 µg m−3, respectively, based on 24-h concentrations thresholds as suggested by US. EPA. However, the levels of PM10 and PM2.5 in poultry houses could be 100 times higher than that limit. For instance, PM10 and PM2.5 levels in cage-free henhouses are higher than 15,000 µg/m3 and 3500 µg/m3 in wintertime. Therefore, it is critical to identify the primary factors affecting PM generation in poultry houses and apply corresponding mitigation strategies. This review paper summarizes PM emission factors, mitigating strategies, and impacts on birds’ and caretakers’ health, and welfare. Generally, PM emissions are affected by various factors, including housing types, seasonal and diurnal variation, manure management, bedding materials, ventilation rates, and birds’ activities. High PM concentrations in poultry houses impair birds’ and caretakers’ liver, kidneys, and respiratory systems. Thus, different mitigating strategies are discussed in this study for addressing those issues. Effective mitigation strategies include frequent house cleaning, optimum light intensity, liquid spraying, bedding management, and air filtration systems. However, mitigation strategies can be cost-prohibitive and have side effects. Therefore, poultry farms should select mitigation strategies based on farm location, climate conditions, environmental policies, and available resources (government assistance programs).

Use of Processed Sugarcane Bagasse Ash in Concrete as Partial Replacement of Cement: Mechanical and Durability Properties

Using biomass waste as supplementary cementing material (SCM) in concrete has attracted researchers’ attention for efficient waste utilization and reducing cement demand. Sugarcane bagasse ash (SCBA) is one such example of biomass waste. It is an agricultural waste obtained when sugarcane bagasse from the sugar industry is used for power generation and disposed of in open-air dumping sites. Its waste disposal causes the generation of particulate matter, degrading air quality. In this study, the effect of processed SCBA as SCM in concrete has been investigated. The processing of the SCBA involved the removal of fibrous and carbon-containing particles by sieving followed by grinding. The SCBA was ground for 45 min until the surface area was comparable to that of cement and was then used for further characterization and incorporation into concrete. The 45 min grinding time resulted in 2.92 times higher pozzolanic reactivity of the SCBA. The SCBA was incorporated by replacing cement in different weight fractions (10%, 20%, 30%, 40%) in concrete. Test results showed that the concrete workability increased with SCBA incorporation, whereas the resulting concrete density was reduced. The results of the mechanical properties, including compressive sstrength and hardened density, were enhanced upon the cement replacement by SCBA. Concrete containing 30% SCBA can be used for structural applications as its 28 days compressive strength was 21 MPa, which complies with ACI 318-16 specifications. Concrete resistance against scaling and leaching due to adverse effects of sulfuric and hydrochloric acid considerably increased with SCBA addition and was due to microstructure densification by secondary hydrates formation as lower portlandite content was detected by thermogravimetric analysis. Hence, SCBA processing increases its reactivity, as reflected by the improved mechanical properties and greater durability of SCBA-incorporated concrete.

The effect of PhIP precursors on the generation of particulate matter in cooking oil fumes at high cooking temperatures and the inflammation response in human lung cells

Cooking Oil Fumes (COFs) contain carcinogenic organic substances such as polycyclic aromatic hydrocarbons (PAHs) and heterocyclic amines (HCAs), of which 2-Amino-1-methyl-6-phenylimidazo(4,5-b)pyridine (PhIP) is known as mainly meat-borne carcinogens. In this work, to identify the mechanisms to induce the inflammation response in human lung cells (A549) exposed to COFs, we investigated the physicochemical and biological characteristics of COFs generated with PhIP precursors (L-phenylalanine, creatinine, and glucose) at high cooking temperatures (300 °C and 600 °C). Interestingly, we found that PhIP was not formed both at 300 °C and 600 °C, while a large number of carbon nanoparticles were generated from soybean oil containing the PhIP precursors at 600 °C. From the biological analysis, COFs generated with the PhIP precursors at 600 °C induced the most significant pro-inflammatory cytokine (IL-6). This result indicates that the particulate matter in COFs generated with the PhIP precursors above the smoke temperature is the primary factor directly affecting the lung inflammatory response rather than PhIP. This study demonstrates for the first time a novel principle of the inflammatory response that the PhIP precursors can aggravate lung injury by affecting the physical properties of COFs depending on cooking temperature. Therefore, our finding is a significant result of overcoming the bias in previous studies focusing only on the chemical toxicity of PhIP in the inflammatory response of COFs.

Carbon Dioxide and Particulate Matter Generation Analysis and Policy Suggestions in Drive-thru Service System

Objectives:Recently, during two-three years of the COVID-19 pandemic, the drive-thru service system has been one of the most actively used non-face-to-face systems to reduce the risk of infection. The business of coffee shops and fast-food restaurants using drive-thru service systems keeps growing. However, carbon dioxide and particulate matter problems in idle running, including traffic congestion and pedestrian safety issue, were brought up in the drive-thru service systems. In this study, carbon dioxide and particulate matter generation were calculated. Also, we proposed existing problems, improvements, and policy issues.Methods:We calculated the carbon dioxide and particulate matter generation in the idle running of vehicles in drive-thru service using several assumptions, the number of vehicles, the idle running time, and emission factors.Results and Discussion:We provided the carbon dioxide and particulate matter generation in the drive-thru service system. Also, we proposed and explained the existing problems, improvements, and policy issues; employees’ respiratory health problems, installation of particulate matter reduction and monitoring system, “Idle Stop & GO” and eco mode use, Performance of environmental improvement charge, single-use cup & product and collection issue.Conclusion:More accurate calculations and studies are needed using more good data such as the number of vehicles, the idle running time, and emission factors. More active policy applications should be considered with revealed problems and proposed improvements in this study.

Laboratory Determination of Gravimetric Correction Factors for Real-time Area Measurements of Electronic Cigarette Aerosols.

Research on secondhand electronic cigarette (ECIG) aerosol exposure using aerosol monitors has demonstrated that ECIG use can generate high concentrations of particulate matter (PM) and impact indoor air quality. However, quantifying indoor air PM concentrations using real-time optical monitors with on-site calibration specifically for different PM exposures has not been established. Therefore, the ECIG aerosol filter correction factors were calculated for different PM sizes (PM1, PM2.5, and PM10) and different aerosol optical monitors, the MiniWRAS, pDR, and SidePak. ECIG aerosol generation was achieved using five ECIGs representing three ECIG types, disposable, pod-mod, and box mod. The aerosol size distribution by mass was measured for the five ECIGs during PM generation. Compared to the discrete filter measurements, the MiniWRAS performed the best when the concentrations were low, followed by the pDR and SidePak. The average PM concentrations and correction factor ranges for the different ECIGs were 323-1,775 μg/m3 and 0.64-6.01 for the MiniWRAS, 1,388-13,365 μg/m3 and 0.41-0.80 for the pDR, and 4,632-55,339 μg/m3 and 0.13-0.20 for the SidePak, respectively. The mass median diameter ranged from 0.41 and 0.62 μm, and most particles generated from the ECIGs were smaller than 1 μm. This study demonstrates that aerosol size distribution varies between ECIGs. Likewise, the correction factors developed for the real-time aerosol monitors are specific to the ECIG used. Thus, these data can help improve ECIG aerosol exposure measurement accuracy.

Trends in particulate matter generation from truck and bus radial tires using a wear tester

AbstractThis study aimed to analyze the trend of particulate matter (PM) generation from tires by nonexhaust systems. These types of PM are lesser known than the airborne PM generated from automotive exhaust systems. Specimens with rubber formulations similar to commercial tires for trucks and buses were artificially abraded, and the generated PM was analyzed. Abrasion of a specimen made of butadiene rubber, which is a synthetic rubber, generated lesser PM than a natural rubber specimen. This reduction of PM generation was particularly significant for PM10. Furthermore, using carbon black (a filler in tires) having small sized particles, the generation of PM2.5 was reduced to a large extent. To study the influence of tire aging on the increased generation of PM, rubber specimens were analyzed after prolonged exposure to a high temperature.

Effects of lubricant-fuel mixing on particle emissions in a single cylinder direct injection spark ignition engine

Gasoline direct injection (GDI) engines emit less carbon dioxide (CO2) than port fuel injection (PFI) engines when fossil fuel conditions are the same. However, GDI engines emit more ultrafine particulate matter, which can have negative health effects, leading to particulate emission regulations. To satisfy these regulations, various studies have been done to reduce particulate matter, and several studies focused on lubricants. This study focuses on the influence of lubricant on the formation of particulate matter and its effect on particulate emissions in GDI engines. An instrumented, combustion and optical singe-cylinder GDI engine fueled by four different lubricant-gasoline blends was used with various injection conditions. Combustion experiments were used to determine combustion characteristics, and gaseous emissions indicated that the lubricant did not influence mixture homogeneity but had an impact on unburned fuels. Optical experiments showed that the lubricant did not influence spray but did influence wall film formation during the injection period, which is a major factor affecting particulate matter generation. Particulate emissions indicated that lubricant included in the wall film significantly affected PN emissions depending on injection conditions. Additionally, the wall film influenced by the lubricant affected the overall particle size and its distribution.

Satellite-Based Analysis of Spatial–Temporal Distributions of NH3 and Factors of Influence in North China

NH3 is an important part of the global nitrogen cycle as the most important atmospheric alkaline gas. NH3 reacts rapidly with acidic substances and accelerates the generation of particulate matter (PM2.5), which has important effects on the atmosphere and climate change. In this study, satellite NH3 column data were used to analyze spatial and temporal distributions of NH3 in China, and because of high concentrations and rates of change, North China was selected for more detailed analysis. Qualitative analysis was conducted to understand the relations between concentrations of NH3 and those of SO2 and NO2. Last, the random forest method was used to quantify relations between concentrations of atmospheric NH3 and factors influencing those concentrations, such as meteorological factors, NH3 self-emission, and concentrations of SO2 and NO2. Satellite-retrieved NH3 column concentrations showed an increasing trend during the 11 years from 2008 to 2018, and the rate of increase in summer was faster than that in winter. In those 11 years, NH3 self-emission had the greatest influence on NH3 concentrations. Concentrations of SO2 and NO2 had some effect and were negatively correlated with NH3 concentrations. The effect of SO2 on NH3 concentration was greater than that of NO2. Atmospheric NH3 concentration was also affected by meteorological conditions (temperature, relative humidity, pressure, and wind). In summer, temperature is the most important factors of meteorological conditions and relative humidity is the most important factors in winter. Therefore, to better control atmospheric NH3 concentrations, it is particularly important to formulate practical NH3 emission reduction policies and to consider the effects of SO2 and NO2 emission reduction policies.

Particulate matter generation in daily activities and removal effect by ventilation methods in residential building

Particulate matter generation in daily activities and removal effect by ventilation methods in residential building

EMISSION OF POLYCYCLIC AROMATIC HYDROCARBONS IN INDOOR AIR DURING BURNING OF MOSQUITO COILS AND THEIR IMPACTS ON THE LIVERS OF THE EXPOSED ALBINO RATS

The indoor burning of mosquito coils (MCs) results in generation of particulate matter (PM) and polycyclic aromatic hydrocarbons (PAHs) in an uncontrolled manner. These emissions pose a serious public health hazards and ecological challenges. Therefore, in the present study the concentrations of PM and its content of PAHs during the indoor application of MCs were determined. In addition, some serum biochemical alternations and histological changes in the liver tissues of male albino rats (Rattus norvegicus) exposed to MC smoke for 8 hours per day over 3-12 weeks were investigated. The concentrations of PM and PAHs in indoor air environment ranged from 210 to 2050 μg/m3 and from 2.57 to 56.76 μg/m3, respectively. In addition, the mean concentration of emission of benzo[a]pyrene (the most carcinogenic PAH) was 4.19±1.10 μg/m3. Serum aminotransferases and alkaline phosphatase activities, as well as serum total protein, triacylglycerol, cholesterol, and low-density lipoprotein levels, were increased significantly in PAHs-exposed rats compared with the control rats (P˂0.05-P˂0.001, n=5). The significant elevation in these parameters was dependent on the duration of exposure. The histological examination of the liver tissues of PAHs-exposed rats showed marked degenerative, vascular and sinusoidal dilatation, and early necrotic changes in hepatocytes alongside fatty steatosis. In conclusion, prolonged exposure to PAHs emitted particles during burning of MCs could cause hepatotoxicity and dyslipidemia. Thus, it is recommended to use MCs only outdoors to reduce their health risk.

Photooxidation of Isoprene by Titanium Oxide Cluster Anions with Dimensions up to a Nanosize.

Titania (TiO2) nanoparticles are active photocatalysts, and isoprene (C5H8) is a biogenic volatile organic compound that contributes crucially to global particulate matter generation. Herein, the direct photooxidation of isoprene by titanium oxide cluster anions with dimensions up to a nanosize by both ultraviolet (UV) and visible (Vis) light excitations has been successfully identified through mass spectrometric experiments combined with quantum chemistry calculations. The potential role of "dry" titania in atmospheric isoprene oxidation has been revealed, and a clear picture of the photooxidation mechanism on titanium oxide nanoparticles has been provided explicitly at the molecular level. The adsorption of isoprene on the atomic oxygen radicals (O•-) of titanium oxide clusters leads to the formation of the crucial interfacial state (IS) within the band gap of titanium oxides. This IS is demonstrated to be the significant factor in delivering the electron from the π orbital of C5H8 to the Ti3d orbital in the photooxidation process (C5H8 + Ti4+-O•- → C5H8O + Ti3+) and creating photoactivity in the Vis region. It is revealed that after the photogeneration of the O•- radicals by UV excitation on the TiO2 particle surface, the subsequent reactions can be induced by Vis excitation through the IS. This multicolor strategy in both the UV and Vis regions can enhance the efficiency of solar energy harvesting and improve the product yield of the photocatalysis on TiO2 nanoparticles. New insights have been provided into both the atmospheric chemistry of isoprene and the photochemistry of TiO2 nanoparticles.

도시 주요 배출원별 미세먼지(TPM) 발생량 예측 및 배출특성 분석

Since particulate matter(PM) is generated from various emission sources when the city is operated, it is necessary to understand the characteristics of PM according to the emission source in order to establish a countermeasure. Therefore, in this study, the total amount of PM generated when the district-level city is operated was predicted for each emission source, and seasonal characteristics were analyzed. In addition, the generation of condensable PM, as well as filterable PM among the total PM, was predicted. As a result, the average percentage of area pollution in the three districts was 43.1% of the total, and the line pollution was analyzed as high as 43.7%. As a seasonal feature, it was analyzed that all pollutants generated more PM in winter than in summer. In particular, the amount of PM in winter generated from building sources was 5.1 times higher than in summer, which was most affected by seasonality among various emission sources.

Environmental impact assessment of Materialization Stage of prefabricated buildings based on LCA and WTP

In recent years, prefabricated buildings have developed rapidly because of their high efficiency and time saving, but the large consumption of resources has also led to many environmental problems. In order to explore the impact of prefabricated buildings on the environment, the environmental impact assessment of the prefabricated buildings based on Life Cycle Assessment Theory (LCA) and Willingness to Pay Theory (WTP) was carried out. First of all, this article combines field research and literature research, using BIM modeling methods to obtain the engineering quantity of prefabricated and cast-in-place buildings. Secondly, analyzing the whole process of the two construction modes based on the life cycle theory, calculate and obtain the consumption list. Next, the ReCiPe method is used to evaluate the environmental impact of prefabricated buildings, and five types of midpoint environmental impact assessment results are obtained: greenhouse gas emissions, fine particulate matter generation, acid gas emissions, energy and mineral resource consumption, etc. Finally, based on the theory of WTP, all kinds of environmental effects are unified for comparative analysis. The results show that the environmental load of the prefabricated construction method is greater than that of the cast-in-place method. It is necessary to further improve the standardization in the production technology and management methods to obtain more advantageous environmental performance.