Phthalate esters(PAEs),typical pollutants widely used as plasticizers,are ubiquitous in various indoor and outdoor environments.PAEs exist in both gas and particle phases,posing risks to human health.In the present st...Phthalate esters(PAEs),typical pollutants widely used as plasticizers,are ubiquitous in various indoor and outdoor environments.PAEs exist in both gas and particle phases,posing risks to human health.In the present study,we chose four typical kinds of indoor and outdoor environments with the longest average human residence times to assess the human exposure in Hangzhou,including newly decorated residences,ordinary residences,offices and outdoor air.In order to analyze the pollution levels and characteristics of 15 gasand particle-phase PAEs in indoor and outdoor environments,air and particulate samples were collected simultaneously.The total PAEs concentrations in the four types of environments were 25,396,25,466.8,15,388.8 and 3616.2 ng/m^3,respectively.DEHP and DEP were the most abundant,and DMPP was at the lowest level.Distinct variations in the distributions of indoor/outdoor,gas/particle-phase and different molecular weights of PAEs were observed,showing that indoor environments were the main sources of PAEs pollution.While most PAEs tended to exsit in indoor sites and gas-phase,the high-molecular-weight chemicals tended to exist in the particle-phase and were mainly found in PM2.5.PAEs were more likely adsorbed by small particles,especially for the indoor environments.There existed a good correlation between the particle matter concentrations and the PAEs levels.In addition,neither temperature nor humidity had obvious effects on the distributions of the PAEs concentrations.展开更多
Exposure to outdoor air pollution has been consistently associated with asthma.In this study,we reviewed the epidemiological studies published within the last 5 years on the association between outdoor air pollution a...Exposure to outdoor air pollution has been consistently associated with asthma.In this study,we reviewed the epidemiological studies published within the last 5 years on the association between outdoor air pollution and exacerbation and onset of asthma.A large number of studies have been published within the last 5 years.Short-term exposure to outdoor air pollution is associated with exacerbation of pre-existing asthma,manifested as worsening of symptoms and increasing of asthma-related emergency room visits and hospital admissions.Furthermore,increasing evidence suggests that long-term exposure to outdoor air pollution can result in onset of asthma.Children are more susceptible to outdoor air pollution.Future studies should be conducted to explore the mechanisms underlying the association between air pollutants and onset of asthma,including gene involvement.In addition,disentangling the effect of a mixture of air pollutants and identifying the key components of air pollution will complete the existing evidence.More importantly,a better understanding is required on the future impact of air pollution on asthma under a changing climate.展开更多
Due to rapid urbanization around the world,high concentrations of vehicular pollutants have deteriorated the outdoor air quality,which can affect the physical and psychological well-being of humans.Numerous strategies...Due to rapid urbanization around the world,high concentrations of vehicular pollutants have deteriorated the outdoor air quality,which can affect the physical and psychological well-being of humans.Numerous strategies have been proposed to overcome these harmful impacts by improving the dispersion of air pollutants.Consequently,a question arises regarding the potential effects of building morphology on the dispersion of pollutants.Subsequently,transient three-dimensional Computational Fluid Dynamics(CFD)simulations are performed to examine the effect of building morphology on PM10 dispersion.Eleven cases with various prototypes and morphological methods are compared with a simple building form to identify the patterns of PM10 dispersion within a given time sequence under a prevailing inflow condition.The results indicate that the different designs of building morphology with varying Relative compactness(RC)indicator highlight the importance of considering morphological factors to improve outdoor air quality.In addition,the proposed prototypes can reduce PM10 concentrations by approximately 30%e90%at specific points in the studied time sequence.In particular,the vertical,horizontal,and grid folded prototypes can be considered more effective as an approximate decrease between 70%and 90%in PM10 concentrations is observed,which reflects the influence of building morphology on improving outdoor air quality.展开更多
DC-inverter split air-conditioner is widely used in Chinese homes as a result of its high-efficiency and energy-saving. Recently, the researches on its outdoor unit have focused on the influence of surrounding structu...DC-inverter split air-conditioner is widely used in Chinese homes as a result of its high-efficiency and energy-saving. Recently, the researches on its outdoor unit have focused on the influence of surrounding structures upon the aerodynamic and acoustic performance, however they are only limited to the influence of a few parameters on the performance, and practical design of the unit requires more detailed parametric analysis. Three-dimensional computational fluid dynamics(CFD) and computational aerodynamic acoustics(CAA) simulation based on FLUENT solver is used to study the influence of surrounding structures upon the aforementioned properties of the unit. The flow rate and sound pressure level are predicted for different rotating speed, and agree well with the experimental results. The parametric influence of three main surrounding structures(i.e. the heat sink, the bell-mouth type shroud and the outlet grille) upon the aerodynamic performance of the unit is analyzed thoroughly. The results demonstrate that the tip vortex plays a major role in the flow fields near the blade tip and has a great effect on the flow field of the unit. The inlet ring's size and throat's depth of the bell-mouth type shroud, and the through-flow area and configuration of upwind and downwind sections of the outlet grille are the most important factors that affect the aerodynamic performance of the unit. Furthermore, two improved schemes against the existing prototype of the unit are developed, which both can significantly increase the flow rate more than 6 %(i.e. 100 m3·h^(-1)) at given rotating speeds. The inevitable increase of flow noise level when flow rate is increased and the advantage of keeping a lower rotating speed are also discussed. The presented work could be a useful guideline in designing the aerodynamic and acoustic performance of the split air-conditioner in engineering practice.展开更多
The paper presents a simple model for outdoor air contaminant transmission into occupied rooms. In the model, several factors such as filtration, ventilation, deposition, re-emission, outdoor concentration and indoor ...The paper presents a simple model for outdoor air contaminant transmission into occupied rooms. In the model, several factors such as filtration, ventilation, deposition, re-emission, outdoor concentration and indoor sources are included. The model results show that the air exchange rate plays an important role in the transmission of outdoor contaminants into the indoor environment. The model shows that increasing the value of the filtration efficiency decreases the mass concentration of indoor particles. In addition, if outdoor aerosol particles have a periodic behaviour, indoor aerosol particles also behave periodically but smoother. Indoor sources are found to be able to increase indoor concentrations greatly and continuously.展开更多
This study aims to measure traffic-related air pollution of vehicles with internal combustion, the main source of emissions of BTEX, organic compounds and NOx, NO2, NO, O3, CO, SO2, PM10 and PM2.5, inorganic compounds...This study aims to measure traffic-related air pollution of vehicles with internal combustion, the main source of emissions of BTEX, organic compounds and NOx, NO2, NO, O3, CO, SO2, PM10 and PM2.5, inorganic compounds, in three sites of the University campus, surrounded by residential areas. According to the University data, around 8000 students are being exposed daily to the measured level of pollution, in all 3 studied places of campus. A mobile laboratory was used, which continuously measures above mentioned pollutants and mete-orological parameters. The diurnal variation of BTEX, in a sunny and rainy day showed two peaks of BTEX concentration in the morning and evening. In the rainy days, the non-polar (hydrophobic) compounds as BTEX are mechanically trained by rain into the ground, where either they enter into the groundwater, or volatilized and re-enter in the air. Particulate matter such as PM10 and PM2.5 is, in a large part, carried by the rain into the soil. The polar compounds (hydrophilic, NOx, SO2) dissolves in the rainwater and are absorbed in the soil (increasing soil acidity) and evaporated towards the clouds (leading to acid rain). In our study, BTEX compounds removed by the rain varied between 62% - 75%, NOx and SO2, 80% and 77% respectively. Particulate matters were washed out up to 68% for PM10, and 42% for PM2.5. In the sunny days the air pollution with measured concentrations of O3 (121.66 ± 7.02, 123.56 ± 4.89 μg/m3) remained for 7 hours close to the limit value (120 μg/m3). The maximum of solar radiation, with corresponding low concentrations in NOx and xylene, corresponds to photochemical reactions in the atmosphere, generating photochemical smog. In a sunny day and high traffic, we found the maximum value 5.4 μg/m3 for benzene, for 30 min., a known human carcinogen, exceeding the annual limit value de 5 μg/m3. The average background, from benzene, in three University campuses daily visited by around 8000 students was 0.97 μg/m3, exposed to 1.46 μg/m3 and the cancer risk is 1/100,000.展开更多
基金supported by the National Key R&D Program of China (No. 2016YFC0207103)the National Natural Science Foundation of China (No. 21607127)the Brain Bridge project with Koninklijke Philips N.V. (No. BB3-2016-01)
文摘Phthalate esters(PAEs),typical pollutants widely used as plasticizers,are ubiquitous in various indoor and outdoor environments.PAEs exist in both gas and particle phases,posing risks to human health.In the present study,we chose four typical kinds of indoor and outdoor environments with the longest average human residence times to assess the human exposure in Hangzhou,including newly decorated residences,ordinary residences,offices and outdoor air.In order to analyze the pollution levels and characteristics of 15 gasand particle-phase PAEs in indoor and outdoor environments,air and particulate samples were collected simultaneously.The total PAEs concentrations in the four types of environments were 25,396,25,466.8,15,388.8 and 3616.2 ng/m^3,respectively.DEHP and DEP were the most abundant,and DMPP was at the lowest level.Distinct variations in the distributions of indoor/outdoor,gas/particle-phase and different molecular weights of PAEs were observed,showing that indoor environments were the main sources of PAEs pollution.While most PAEs tended to exsit in indoor sites and gas-phase,the high-molecular-weight chemicals tended to exist in the particle-phase and were mainly found in PM2.5.PAEs were more likely adsorbed by small particles,especially for the indoor environments.There existed a good correlation between the particle matter concentrations and the PAEs levels.In addition,neither temperature nor humidity had obvious effects on the distributions of the PAEs concentrations.
文摘Exposure to outdoor air pollution has been consistently associated with asthma.In this study,we reviewed the epidemiological studies published within the last 5 years on the association between outdoor air pollution and exacerbation and onset of asthma.A large number of studies have been published within the last 5 years.Short-term exposure to outdoor air pollution is associated with exacerbation of pre-existing asthma,manifested as worsening of symptoms and increasing of asthma-related emergency room visits and hospital admissions.Furthermore,increasing evidence suggests that long-term exposure to outdoor air pollution can result in onset of asthma.Children are more susceptible to outdoor air pollution.Future studies should be conducted to explore the mechanisms underlying the association between air pollutants and onset of asthma,including gene involvement.In addition,disentangling the effect of a mixture of air pollutants and identifying the key components of air pollution will complete the existing evidence.More importantly,a better understanding is required on the future impact of air pollution on asthma under a changing climate.
文摘Due to rapid urbanization around the world,high concentrations of vehicular pollutants have deteriorated the outdoor air quality,which can affect the physical and psychological well-being of humans.Numerous strategies have been proposed to overcome these harmful impacts by improving the dispersion of air pollutants.Consequently,a question arises regarding the potential effects of building morphology on the dispersion of pollutants.Subsequently,transient three-dimensional Computational Fluid Dynamics(CFD)simulations are performed to examine the effect of building morphology on PM10 dispersion.Eleven cases with various prototypes and morphological methods are compared with a simple building form to identify the patterns of PM10 dispersion within a given time sequence under a prevailing inflow condition.The results indicate that the different designs of building morphology with varying Relative compactness(RC)indicator highlight the importance of considering morphological factors to improve outdoor air quality.In addition,the proposed prototypes can reduce PM10 concentrations by approximately 30%e90%at specific points in the studied time sequence.In particular,the vertical,horizontal,and grid folded prototypes can be considered more effective as an approximate decrease between 70%and 90%in PM10 concentrations is observed,which reflects the influence of building morphology on improving outdoor air quality.
基金Supported by Program for Changjiang Scholars and Innovative Research Team in University,Ministry of Education of China(PCSIRT)
文摘DC-inverter split air-conditioner is widely used in Chinese homes as a result of its high-efficiency and energy-saving. Recently, the researches on its outdoor unit have focused on the influence of surrounding structures upon the aerodynamic and acoustic performance, however they are only limited to the influence of a few parameters on the performance, and practical design of the unit requires more detailed parametric analysis. Three-dimensional computational fluid dynamics(CFD) and computational aerodynamic acoustics(CAA) simulation based on FLUENT solver is used to study the influence of surrounding structures upon the aforementioned properties of the unit. The flow rate and sound pressure level are predicted for different rotating speed, and agree well with the experimental results. The parametric influence of three main surrounding structures(i.e. the heat sink, the bell-mouth type shroud and the outlet grille) upon the aerodynamic performance of the unit is analyzed thoroughly. The results demonstrate that the tip vortex plays a major role in the flow fields near the blade tip and has a great effect on the flow field of the unit. The inlet ring's size and throat's depth of the bell-mouth type shroud, and the through-flow area and configuration of upwind and downwind sections of the outlet grille are the most important factors that affect the aerodynamic performance of the unit. Furthermore, two improved schemes against the existing prototype of the unit are developed, which both can significantly increase the flow rate more than 6 %(i.e. 100 m3·h^(-1)) at given rotating speeds. The inevitable increase of flow noise level when flow rate is increased and the advantage of keeping a lower rotating speed are also discussed. The presented work could be a useful guideline in designing the aerodynamic and acoustic performance of the split air-conditioner in engineering practice.
基金Funded by Beijing Higher Education Young Elite Teacher Project(No.YETP0371)National Key Technologies R&D Program of China(No.2012BAJ02B02)
文摘The paper presents a simple model for outdoor air contaminant transmission into occupied rooms. In the model, several factors such as filtration, ventilation, deposition, re-emission, outdoor concentration and indoor sources are included. The model results show that the air exchange rate plays an important role in the transmission of outdoor contaminants into the indoor environment. The model shows that increasing the value of the filtration efficiency decreases the mass concentration of indoor particles. In addition, if outdoor aerosol particles have a periodic behaviour, indoor aerosol particles also behave periodically but smoother. Indoor sources are found to be able to increase indoor concentrations greatly and continuously.
文摘This study aims to measure traffic-related air pollution of vehicles with internal combustion, the main source of emissions of BTEX, organic compounds and NOx, NO2, NO, O3, CO, SO2, PM10 and PM2.5, inorganic compounds, in three sites of the University campus, surrounded by residential areas. According to the University data, around 8000 students are being exposed daily to the measured level of pollution, in all 3 studied places of campus. A mobile laboratory was used, which continuously measures above mentioned pollutants and mete-orological parameters. The diurnal variation of BTEX, in a sunny and rainy day showed two peaks of BTEX concentration in the morning and evening. In the rainy days, the non-polar (hydrophobic) compounds as BTEX are mechanically trained by rain into the ground, where either they enter into the groundwater, or volatilized and re-enter in the air. Particulate matter such as PM10 and PM2.5 is, in a large part, carried by the rain into the soil. The polar compounds (hydrophilic, NOx, SO2) dissolves in the rainwater and are absorbed in the soil (increasing soil acidity) and evaporated towards the clouds (leading to acid rain). In our study, BTEX compounds removed by the rain varied between 62% - 75%, NOx and SO2, 80% and 77% respectively. Particulate matters were washed out up to 68% for PM10, and 42% for PM2.5. In the sunny days the air pollution with measured concentrations of O3 (121.66 ± 7.02, 123.56 ± 4.89 μg/m3) remained for 7 hours close to the limit value (120 μg/m3). The maximum of solar radiation, with corresponding low concentrations in NOx and xylene, corresponds to photochemical reactions in the atmosphere, generating photochemical smog. In a sunny day and high traffic, we found the maximum value 5.4 μg/m3 for benzene, for 30 min., a known human carcinogen, exceeding the annual limit value de 5 μg/m3. The average background, from benzene, in three University campuses daily visited by around 8000 students was 0.97 μg/m3, exposed to 1.46 μg/m3 and the cancer risk is 1/100,000.
