Diverse Metabolic Effects of Cooking Oil Fume from Four Edible Oils on Human BEAS-2B Cells: Implications for Health Guidelines.

The 2021 WHO guidelines stress the importance of measuring ultrafine particles using particle number concentration (PNC) for health assessments. However, commonly used particle metrics such as aerodynamic diameter and number concentrations do not fully capture the diverse chemical makeup of complex particles. To address this issue, our study used high-throughput mass spectrometry to analyze the properties of cooking oil fumes (COFs) in real time and evaluate their impact on BEAS-2B cell metabolism. Results showed insignificant differences in COF number size distributions between soybean oil and olive oil (peak concentrations of 5.20 × 105/cm3), as well as between corn oil and peanut oil (peak concentrations of 4.35 × 105/cm3). Despite the similar major chemical components among the four COFs, variations in metabolic damage were observed, indicating that the relatively small amount of chemical components of COFs can also influence particle behavior within the respiratory system, thereby impacting biological responses. Additionally, interactions between accompanying gaseous COFs and particles may alter their chemical composition through various mechanisms, introducing additional chemicals and modifying existing proportions. Hence, the chemical composition and gaseous components of COFs hold equal importance to the particle number concentration (PNC) when assessing their impact on human health. The absence of these considerations in the current guidelines underscores a research gap. It is imperative to acknowledge that for a more comprehensive approach to safeguarding public health, guidelines must be regularly updated to reflect new scientific findings and robust epidemiological evidence.

Exposure to ambient air pollution and metabolic dysfunction-associated fatty liver disease: Findings from over 2.7 million adults in Northwestern China.

Ambient air pollutants exposures may lead to aggravated Metabolic Dysfunction-Associated Fatty Liver Disease (MAFLD). However, there is still a scarcity of empirical studies that have rigorously estimated this association, especially in regions where air pollution is severe. To fill in the literature gap, we conducted a cross-sectional study involving 2711,207 adults living in five regions of southern Xinjiang Uyghur Autonomous Region in 2021. Using a Space-Time Extra-Trees model, we assessed the four-year (2017-2020) average concentrations of particulate matter with aerodynamic diameter ≤1 µm (PM1), particulate matter with aerodynamic diameter ≤2.5 µm (PM2.5), particulate matter with aerodynamic diameter ≤10 µm (PM10), ozone (O3), sulfur dioxide (SO2), and carbon monoxide (CO), and then assigned these values to the participants. Generalized linear mixed models were employed to examine the relationships between air pollutants and the prevalence of MAFLD, with adjustment for multiple confounding factors. The odds ratios and 95% confidence intervals of MAFLD were 2.002 (1.826-2.195), 1.133 (1.108-1.157), 1.034 (1.027-1.040), 1.077 (1.023-1.134), 2.703 (2.322-3.146) and 1.033 (1.029-1.036) per 10 µg/m3 increase in the 4-year average PM1, PM2.5, PM10, O3, SO2 and CO exposures, respectively. The robustness of the findings was confirmed by a series of sensitivities. In summary, long-term exposure to ambient air pollutants was associated with increased odds of MAFLD, particularly in males and individuals with unhealthy lifestyles.

The association between ambient air pollution and migraine: a systematic review.

Some studies have shown the effect of air pollution on migraine. However, it needs to be confirmed in larger-scale studies, as scientific evidence is scarce regarding the association between air pollution and migraine. Therefore, this systematic review aims to determine whether there are associations between outdoor air pollution and migraine. A literature search was performed in Scopus, Medline (via PubMed), EMBASE, and Web of Science. A manual search for resources and related references was also conducted to complete the search. All observational studies investigating the association between ambient air pollution and migraine, with inclusion criteria, were entered into the review. Fourteen out of 1417 identified articles met the inclusion criteria and entered the study. Among the gaseous air pollutants, there was a correlation between exposure to nitrogen dioxide (NO2) (78.3% of detrimental relationships) and carbon monoxide (CO) (68.0% of detrimental relationships) and migraine, but no apparent correlation has been found for sulfur dioxide (SO2) (21.2% of detrimental relationships) and ozone (O3) (55.2% of detrimental relationships). In the case of particulate air pollutants, particulate matter with a diameter of 10 µm or less (PM10) (76.0% of detrimental relationships) and particulate matter with a diameter of 2.5 µm or less (PM2.5) (61.3% of detrimental relationships) had relationships with migraine. In conclusion, exposure to NO2, CO, PM10, and PM2.5 is associated with migraine headaches, while no conclusive evidence was found to confirm the correlation between O3 and SO2 with migraine. Further studies with precise methodology are recommended in different cities around the world for all pollutants with an emphasis on O3 and SO2.

Air biofilters for a mixture of organic gaseous pollutants: an approach for industrial applications.

Hazardous airborne pollutants are frequently emitted to the atmosphere in the form of a gaseous mixture. Air biofilters as the primary biotechnological choice for waste gas treatment (low inlet concentration and high gas flow rate) should run properly when the feed contains multiple pollutants. Simultaneous removal of pollutants in biofilters has been extensively studied over the last 10 years. In this review, the results and findings of the mentioned studies including different groups of pollutants, such as methane (CH4) and volatile organic compounds (VOCs) are discussed. As the number of pollutants in a mixture increases, their elimination might become more complicated due to interactions between the pollutants. Parallel batch studies might be helpful to better understand these interaction effects in the absence of mass transfer limitations. Setting optimum operating conditions for removal of mixtures in biofilters is challenging because of opposing properties of pollutants. In biofilters, concerns, such as inlet gas composition variation and stability while dealing with abrupt inlet load and concentration changes, must be managed especially at industrial scales. Biofilters designed with multi-layer beds, allow tracking the fate of each pollutant as well as analyzing the diversity of microbial culture across the filter bed. Certain strategies are recommended to improve the performance of biofilters treating mixtures. For example, addition of (bio)surfactants as well as a second liquid phase in biotrickling filters might be considered for the elimination of multiple pollutants especially when hydrophobic pollutants are involved.

Ambient air pollution and gestational diabetes mellitus: An updated systematic review and meta-analysis.

OBJECTIVE: We aimed to evaluate the relationship between the composition of particulate matter (PM) and gestational diabetes mellitus (GDM) by a comprehensively review of epidemiological studies. METHODS: We systematically identified cohort studies related to air pollution and GDM risk before February 8, 2023 from six databases (PubMed, Embase, Web of Science Core Collection, China National Knowledge Infrastructure, Wanfang Data Knowledge Service Platform and Chongqing VIP Chinese Science and Technology Periodical databases). We calculated the relative risk (RR) and its 95% confidence intervals (CIs) to assess the overall effect by using a random effects model. RESULTS: This meta-analysis of 31 eligible cohort studies showed that exposure to PM2.5, PM10, SO2, and NO2 was associated with a significantly increased risk of GDM, especially in preconception and first trimester. Analysis of the components of PM2.5 found that the risk of GDM was strongly linked to black carbon (BC) and nitrates (NO3-). Specifically, BC exposure in the second trimester and NO3- exposure in the first trimester elevated the risk of GDM, with the RR of 1.128 (1.032-1.231) and 1.128 (1.032-1.231), respectively. The stratified analysis showed stronger correlations of GDM risk with higher levels of pollutants in Asia, except for PM2.5 and BC, which suggested that the specific composition of particulate pollutants had a greater effect on the exposure-outcome association than the concentration. CONCLUSIONS: Our study found that ambient air pollutant is a critical factor for GDM and further studies on specific particulate matter components should be considered in the future.

Systematic control technologies for gaseous pollutants from non-ferrous metallurgy.

Air pollutant emissions represent a critical challenge in the green development of the non-ferrous metallurgy industry. This work studied the emission characteristics, formation mechanisms, phase transformation and separation of typical air pollutants, such as heavy metal particles, mercury, sulfur oxides and fluoride, during non-ferrous smelting. A series of purification technologies, including optimization of the furnace throat and high-temperature discharge, were developed to collaboratively control and recover fine particles from the flue gas of heavy metal smelting processes, including copper, lead and zinc. Significant improvements have been realized in wet scrubbing technology for removing mercury, fluoride and SO2 from flue gas. Gas-liquid sulfidation technology by applying H2S was invented to recycle the acid scrubbing wastewater more efficiently and in an eco-friendly manner. Based on digital technology, a source reduction method was designed for sulfur and fluoride control during the whole aluminum electrolysis process. New desulfurization technologies were developed for catalytic reduction of the sulfur content in petroleum coke at low temperature and catalytic reduction of SO2 to elemental sulfur. This work has established the technology for coupling multi-pollutant control and resource recovery from the flue gas from non-ferrous metallurgy, which provides the scientific theoretical basis and application technology for the treatment of air pollutants in the non-ferrous metallurgy industry.

Exposure to ambient air pollutants with kidney function decline in chronic kidney disease patients.

Chronic kidney disease (CKD) has been a global public health problem with many adverse outcomes, but data are lacking regarding the relationship between air pollutants and risk of renal progression in patients with CKD. This study was to investigate whether 1-year average exposure to ambient air pollutants -CO, NO, NO2, SO2, O3, PM2.5, and PM10-is related to renal function deterioration among patients with CKD. A total of 5301 CKD patients were included in this study between October 2008 and February 2016. To estimate each patient's exposure to ambient air pollution, we used the 24-h ambient air pollution concentration monitoring data collected one year prior to renal progression or their last renal function assessment. Renal progression was considered when estimated glomerular filtration rate (eGFR) decreased more than 25% from the baseline eGFR. Cox proportional hazard regression was performed to calculate hazard ratios (HRs). Among 5301 patients with CKD, 1813 (34.20%) developed renal progression during the 30.48 ± 14.99-month follow-up. Patients with the highest quartile exposure to CO [HR = 1.53 (95% CI: 1.24, 1.88)], NO [HR = 1.38 (95% CI: 1.11, 1.71)], NO2 [HR = 1.63 (95% CI: 1.36, 1.97)], SO2 [HR = 2.27 (95% CI: 1.83, 2.82)], PM2.5 [HR = 7.58 (95% CI: 5.97, 9.62)], and PM10 [HR = 3.68 (95% CI: 2.84, 4.78)] had a significantly higher risk of renal progression than those with the lowest quartile exposure. In the multipollutant model, the analyses yielded to similar results. These results reinforce the importance of measures to mitigate air pollution and strategies to prevent worsening of kidney function in patients with CKD. One-year high exposure to ambient CO, NO, NO2, SO2, PM2.5, and PM10 is significantly associated with deteriorated kidney function in patients with CKD among Taiwanese adults.

Airborne infection risk of inter-unit dispersion through semi-shaded openings: A case study of a multi-storey building with external louvers.

Building design for natural ventilation and indoor air quality have become increasingly important during the past decades. Investigating airflow routes of airborne transmission and evaluating the potential infection risk in the multi-storey building is helpful to the reduction of airborne transmission. Therefore, this study applies computational fluid dynamics simulations to investigate the inter-unit dispersion pattern of gaseous pollutant between different units through semi-shaded openings. The airflow exchange and pollutant dispersion in a multi-storey building is driven by wind-induced natural ventilation. External shading louvers, which are widely used in building facades to reduce heat gain from solar radiation, are chosen to establish the semi-shaded environment. Experimental validation is performed to make sure the accuracy of numerical settings in airflow investigation of semi-shaded openings. The airflow characteristics around semi-shaded openings is analyzed in the numerical simulations. The re-entry ratio of tracer gas and the airborne infection risk of COVID-19 is investigated in the cases with different louvers' locations and source units. The results show that the airflow is commonly slower in the semi-shaded space between louvers and openings. But the ventilation rate is not always consistent with the airflow speed because of the diversion effect from louver slats. The inter-unit infectious risk in the worst unit rises from 7.82% to 26.17% for windward shading, while it rises from 7.89% to 22.52% for leeward shading. These results are helpful to the further understanding of inter-unit transmission of infectious respiratory aerosols through external openings with complex structures.

Real-world gaseous emission characteristics of natural gas heavy-duty sanitation trucks.

As compared to conventional diesel heavy-duty vehicles, natural gas vehicles have been proved to be more eco-friendly due to their lower production of greenhouse gas and pollutant emissions, which are causing enormous adverse effects on global warming and air pollution. However, natural gas vehicles were rarely studied before, especially through on-road measurements. In this study, a portable emission measurement system (PEMS) was employed to investigate the real-world emissions of nitrogen oxides (NOx) (nitrogen monoxide (NO), nitrogen dioxide (NO2)), total hydrocarbons (THC), carbon monoxide (CO), and carbon dioxide (CO2) from two liquified natural gas (LNG) China V heavy-duty cleaning sanitation trucks with different weight. Associated with the more aggressive driving behaviors, the vehicle with lower weight exhibited higher CO2 (3%) but lower NOx (48.3%) (NO2 (78.2%) and NO (29.4%)), CO (44.8%), and THC (3.7%) emission factors. Aggressive driving behaviors were also favorable to the production of THC, especially those in the medium-speed range but significantly negative to the production of CO and NO2, especially those in the low-speed range with high engine load. In particular, the emission rate ratio of NO2/NO decreased with the increase of speed/scaled tractive power in different speed ranges.

Phosphonium ionic liquid-promoted Ce-doped nitrogen-rich TiO2for degradation gaseous pollutant under visible light irradiation.

Altering physicochemical properties of TiO2based on modifying the cation and anion structure of ionic liquids (ILs) is of great interests for environment. Up to date, the research involving IL-assisted synthesis of TiO2was focused on imidazolium IL, and much less attention was devoted to IL with other structures. Hence, strategy for preparation of TiO2in phosphonium IL is presented to control the growth of TiO2nanocrystals. The as-prepared noble cerium-doped nitrogen-rich phosphonium IL-TiO2photocatalyst with assisted by tributyl(propyl)phosphonium tetrafluoroborate exhibits a higher specific surface area and smaller crystallite size, which is conducive to the production of more and faster active substance, such as hydroxyl oxygen. When evaluated for photocatalysis of gaseous toluene under visible light irradiation, the sample manifests high degradation rate and efficiency, as well as excellent recycling performance due to the existence of superoxide radical produced by the Ce3+/Ce4+redox reaction. The introduction of phosphonium IL and Ce greatly enhanced charge separation efficiency and promoted production of active substances. Nitrogen also existed in the form of interstitial nitrogen and substituted nitrogen improves its response to visible light. This work shows promising application of phosphonium IL for highly enhanced TiO2photocatalytic performance.

Prolonged exposure to traffic-related particulate matter and gaseous pollutants implicate distinct molecular mechanisms of lung injury in rats.

BACKGROUND: Exposure to air pollution exerts direct effects on respiratory organs; however, molecular alterations underlying air pollution-induced pulmonary injury remain unclear. In this study, we investigated the effect of air pollution on the lung tissues of Sprague-Dawley rats with whole-body exposure to traffic-related PM1 (particulate matter < 1 µm in aerodynamic diameter) pollutants and compared it with that in rats exposed to high-efficiency particulate air-filtered gaseous pollutants and clean air controls for 3 and 6 months. Lung function and histological examinations were performed along with quantitative proteomics analysis and functional validation. RESULTS: Rats in the 6-month PM1-exposed group exhibited a significant decline in lung function, as determined by decreased FEF25-75% and FEV20/FVC; however, histological analysis revealed earlier lung damage, as evidenced by increased congestion and macrophage infiltration in 3-month PM1-exposed rat lungs. The lung tissue proteomics analysis identified 2673 proteins that highlighted the differential dysregulation of proteins involved in oxidative stress, cellular metabolism, calcium signalling, inflammatory responses, and actin dynamics under exposures to PM1 and gaseous pollutants. The presence of PM1 specifically enhanced oxidative stress and inflammatory reactions under subchronic exposure to traffic-related PM1 and suppressed glucose metabolism and actin cytoskeleton signalling. These factors might lead to repair failure and thus to lung function decline after chronic exposure to traffic-related PM1. A detailed pathogenic mechanism was proposed to depict temporal and dynamic molecular regulations associated with PM1- and gaseous pollutants-induced lung injury. CONCLUSION: This study explored several potential molecular features associated with early lung damage in response to traffic-related air pollution, which might be used to screen individuals more susceptible to air pollution.

Air pollution and multiple sclerosis: a comprehensive review.

Multiple sclerosis (MS) is an inflammatory, autoimmune demyelinating disorder of the central nervous system (CNS), leading to progressive functional impairments, and many intrinsic and acquired factors are believed to be associated with its development and relapse. In terms of environmental factors, air pollution has gained much attention during recent decades, as chronic exposure to ambient air pollution seems to increase the level of some pro-inflammatory markers in the human brain, which can lead to neuroinflammation, neurodegeneration, and blood-brain barrier (BBB) breakdown. These events may also be associated with the risk of MS development and relapse. In this review, we aimed to summarize recent findings around the impact of air pollutants, including particulate matter (PM10, PM2.5, and ultra-fine particles), gaseous pollutants (carbon monoxide [CO], nitrogen oxides [NOx], sulfur dioxide [SO2], and ozone [O3]), and heavy metals, on MS development and relapse.

The association between gaseous pollutants and non-accidental mortality: a time series study.

To evaluate the effects of gaseous pollutants (SO2, NO2) on non-accidental mortality of residents in Hefei city, we collected non-accidental deaths, air pollutants and meteorological data of Hefei city from 2014 to 2017. After controlling confounding factors with Poisson generalized additive model, we analyzed the relationship between air pollutants and non-accidental mortality and used subgroup analysis to identify susceptible groups. The number of non-accidental deaths during the study period was 42,116, with an average of 28.83 per day. The average concentrations of SO2 and NO2 were 16.08 µg/m3 and 39.10 µg/m3, respectively. In the single-pollutant model, every 10 µg/m3 increase in SO2 and NO2 concentrations was significantly associated with non-accidental mortality, and there was a significant lag effect. SO2 increased the risk of non-accidental death by 4.93% (95% CI: 1.94% ~ 8.00%) at lag0-3. In addition, male, the elderly, non-elderly and low-education people were more susceptible (P < 0.05). NO2 increased the risk of non-accidental death by 2.11% (95% CI: 1.18% ~ 3.05%) at lag0-1 and had an effect on all subgroups (P < 0.05). For every 10 µg/m3 increase in SO2 and NO2, the two-pollutant model showed that the risk of non-accidental death, respectively, increased by 3.34% (95% CI: 0.29% ~ 6.50%) and 1.82% (95% CI: 0.85% ~ 2.79%), suggesting that the effect was weakened. Our study suggested that SO2 and NO2 were associated with non-accidental mortality, and there were lag effects. Therefore, environmental management should be strengthened and health protection education should be carried out for different groups.

Ambient air pollution and homocysteine: Current epidemiological evidence and a call for further research.

Elevated blood homocysteine (Hcy) is an independent risk factor for cardiovascular disease. A growing number of studies have evaluated the link between air pollution and blood Hcy levels, but the results are inconsistent. To date, no systematic review of the published studies has been conducted yet. We aimed to provide a comprehensive overview of these studies. We systematically searched three international databases (PubMed, Web of Science, and Embase) and four Chinese databases (Wanfang, CNKI, CBM, and VIP) for peer-reviewed epidemiological studies investigating associations between ambient air pollutants and Hcy levels published before December 2019. We screened literature, extracted data, assessed methodological quality, and evaluated the risk of bias of the included studies. Of 1157 identified articles, 10 were finally included in this systematic review. Most were cross-sectional studies and were performed in developed countries. Particulate matter with aerodynamic diameters less than 2.5 µm (PM2.5) and/or 10 µm (PM10) were investigated in all of the included studies. Overall, the evidence generally supports a positive association between higher PM concentrations and elevated Hcy levels. However, high heterogeneity in terms of study participants, study design, exposure duration, and particle components and sources, low methodological quality and probable high risk of bias in some studies, and limited literature number precluded us from drawing a robust conclusion. Associations between Hcy and gaseous pollutants were explored in only one or two studies, and the results were inconclusive. Additional, well-designed studies remain required to validate the association between air pollution and Hcy.

Ambient air pollution and diabetes: A systematic review and meta-analysis.

BACKGROUND: Air pollutants are suggested to be related to type 2 diabetes (T2D). Since several high quality papers on air pollutants and T2D have been published beyond the last reviews, an extended systematic review is highly warranted. We review epidemiological studies to quantify the association between air pollutants and T2D, and to answer if diabetes patients are more vulnerable to air pollutants. METHODS: We systematically reviewed the databases of PubMed and Web of Science based on the guidelines of the Preferred Reporting Items for Systematic review and Meta-analysis (PRISMA). We calculated odds ratios (OR) or hazard ratios (HR) and their 95% confidence intervals (CI) to assess the strength of the associations between air pollutants [e.g., particulate matter with diameter ≤ 2.5 µm (PM2.5), particulate matter with diameter ≤ 10 µm (PM10), and nitrogen dioxide (NO2)] and T2D. We evaluated the quality and risk of bias of the included studies and graded the credibility of the pooled evidence using several recommended tools. We also performed sensitivity analysis, meta-regression analysis, and publication bias test. RESULTS: Out of 716 articles identified, 86 were used for this review and meta-analysis. Meta-analyses showed significant associations of PM2.5 with T2D incidence (11 studies; HR = 1.10, 95% CI = 1.04-1.17 per 10 µg/m3 increment; I2 = 74.4%) and prevalence (11 studies; OR = 1.08; 95% CI = 1.04-1.12 per 10 µg/m3 increment; I2 = 84.3%), of PM10 with T2D prevalence (6 studies; OR = 1.10; 95% CI = 1.03-1.17 per 10 µg/m3 increment; I2 = 89.5%) and incidence (6 studies; HR = 1.11; 95% CI = 1.00-1.22 per µg/m3 increment; I2 = 70.6%), and of NO2 with T2D prevalence (11 studies; OR = 1.07; 95% CI = 1.04-1.11 per 10 µg/m3 increment; I2 = 91.1%). The majority of studies on glucose-homoeostasis markers also showed increased risks with higher air pollutants levels, but the studies were too heterogeneous for meta-analysis. Overall, patients with diabetes might be more vulnerable to PM. CONCLUSIONS: Recent publications strengthened the evidence for adverse effects of ambient air pollutants exposure (especially for PM) on T2D and that diabetic patients might be more vulnerable to air pollutants exposure.

Numerical investigation of gaseous pollutant cross-transmission for single-sided natural ventilation driven by buoyancy and wind.

Single-sided natural ventilation was numerically investigated to determine the impact of buoyancy and wind on the cross-transmission of pollution by considering six window types commonly found in multistory buildings. The goal of this study was to predict the gaseous pollutant transmission using computational fluid dynamics based on the Reynolds-averaged Navier-Stokes equations and baseline k-ω turbulence equations. The results indicated that ventilation rates generally increased with increasing wind speeds if the effects of buoyancy and wind were not suppressed; however, the re-entry ratio representing the proportion of expelled air re-entering other floors and the corresponding risk of infection decreased. If the source of the virus was on a central floor, the risk of infection was the highest on the floors closest to the source. Different window types were also considered for determining their effectiveness in controlling cross-transmission and infection risk, depending on the source location and driving force (e.g., buoyancy and wind).

Long-term exposure to ambient air pollution (including PM1) and metabolic syndrome: The 33 Communities Chinese Health Study (33CCHS).

Little evidence exists about the effects of long-term exposure to ambient air pollution on metabolic syndrome (MetS). This study aimed to determine the association between long-term ambient air pollution and MetS in China. A total of 15,477 adults who participated in the 33 Communities Chinese Health Study (33CCHS) in 2009 were evaluated. MetS was defined based on the recommendation by the Joint Interim Societies. Exposure to air pollutants was assessed using data from monitoring stations and a spatial statistical model (including particles with diameters ≤ 1.0 µm (PM1), ≤ 2.5 µm (PM2.5), and ≤ 10 µm (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), and ozone (O3)). Two-level logistic regression analyses were utilized to assess the associations between air pollutants and MetS. The prevalence of MetS was 30.37%. The adjusted odds ratio of MetS per 10 µg/m3 increase in PM1, PM2.5, PM10, SO2, NO2, and O3 were 1.12 (95% CI = 1.00-1.24), 1.09 (95% CI = 1.00-1.18), 1.13 (95% CI = 1.08-1.19), 1.10 (95% CI = 1.02-1.18), 1.33 (95% CI = 1.12-1.57), and 1.10 (95% CI = 1.01-1.18), respectively. Stratified analyses indicated that the above associations were stronger in participants with the demographic variables of males, < 50 years of age, and higher income, as well as with the behavioral characteristics of smoking, drinking, and consuming sugar-sweetened soft drinks frequently. This study indicates that long-term exposure to ambient air pollutants may increase the risk of MetS, especially among males, the young to middle aged, those of low income, and those with unhealthy lifestyles.

Gaseous pollutant transmission through windows between vertical floors in a multistory building with natural ventilation.

Natural ventilation is an effective strategy to control thermal comfort in buildings, and can be enhanced depending on the window style. The combination of natural ventilation and window can also facilitate the removal or dilution of gaseous pollutants from indoor sources in newly decorated buildings. However, the windows on the same facade may cause gaseous pollutant cross-transmission during single-sided natural ventilation between households on different floors close to the source. Although some research has focused on the pollutant cross-transmission in buildings, the simplification of windows into rectangular openings often affects accurate knowledge of pollutant transmission characteristics. Therefore, this investigation explored gaseous pollutant cross-transmission through real windows during single-sided, buoyancy-driven ventilation in a multistory building. Six types of windows were modeled for the indoor pollutant of gaseous formaldehyde (HCHO). Computational fluid dynamics (CFD) was utilized to solve characteristics of pollutant transmission inside and outside the multistory building. The results indicated that the ventilation rates, thermal profiles and pollutant transmission inside and outside the building varied for each window type, although the open window areas were identical. The re-entry ratio of exhausted air entering upper floors and the infection risk of epidemic viruses caused by airborne cross-transmission was sensitive to ventilation rates and window configurations, while the sensitivities for window configurations varied case by case. The comparisons also revealed that the specification of ambient temperature and pollutant release rate ultimately did not affect the evaluation of pollutant cross-transmission using CFD.

Analysis and pollution sources speculations of toxic gases in a secondary fiber paper mill.

This paper quantitatively investigates the compositions of the gaseous pollutants in the ambient air of a secondary fiber paper mill. Total volatile organic compounds (TVOC), formaldehyde (HCHO), sulfur compounds (H2S), and hydrocarbon compounds (CxHy) were analyzed on six sampling sites with photo-ionisation detector, acetylacetone spectrophotometric method, and gas detector. The results revealed that, the high levels of TVOC and CxHy were detected at the wet end of paper machine and the office area, respectively; all the H2S contents on the six sites exceeded the limit (0.06 mg m(-3)) seriously; the HCHO concentrations at other five sites were out of the limit (0.10 mg m(-3)) except for the wastewater treatment plant. Furthermore, the necessary discussions about the possible pollution sources were considered on the process flow, the chemical agents used, and the ambient conditions in the paper mill. For the sake of air pollution control in paper mills, these remarkable results and analysis lay some technical basis in the following researches that should attract more attentions.

Wind tunnel tests of inter-flat pollutant transmission characteristics in a rectangular multi-storey residential building, part A: Effect of wind direction.

The inter-flat dispersion of hazardous air pollutants in residential built environment has become a growing concern, especially in crowed urban areas. The purpose of present study is to investigate the wind induced air pollutant transmission and cross contamination routes in typical buildings. In this paper, a series of experiments was carried out in a boundary layer wind tunnel using a 1:30 scaled model that represented the typical configuration of rectangular multi-storey residential buildings in Shanghai. Sulfur hexafluoride (SF6) was employed as tracer gas in the wind tunnel tests. The conditions under two ventilation modes, i.e. single-sided natural ventilation and cross natural ventilation, were compared. The tracer gas concentration distributions under four approaching wind angles were monitored and analyzed. Computational Fluid Dynamics (CFD) method was adopted to assist in analyzing airflow patterns. The experiment results elucidated that in the two ventilation scenarios, both of the vertical and horizontal inter-flat airborne transmission could proceed. The wind direction played a key role on the pollutant concentration distribution. Compared with the single-sided ventilation mode, cross ventilation could weaken the air pollutant dispersion along the vertical direction when the contamination source was on the windward or on the leeward unit. When the wind blowing parallelly to the source unit window, namely the source room was on the sideward, cross ventilation would not suppress the vertical transport on one hand, but reinforce the horizontal transmission on the other hand. The study is helpful for the analysis of infection risk of respiratory diseases in the residential buildings.