Objective Air-borne particulates from different sources could have different physicochemical properties and inflammatory potentials. This study aims to characterize the chemical compositions and the toxicity of ambien...Objective Air-borne particulates from different sources could have different physicochemical properties and inflammatory potentials. This study aims to characterize the chemical compositions and the toxicity of ambient particulate matter （PM） associated with traffic emissions. Methods The concentrations of trace elements, organic carbon （OC）, elemental carbon （EC） and polycyclic aromatic hydrocarbons （PAHs） in PM2.5 and PMlo were measured in samples collected at sites in Beijing, China. Their toxic effects on the pulmonary system of rats were investigated. Biochemical parameters （LDH, T-AOC, TP） and inflammatory cytokine（IL-6, IL-1, TNF-a） levels were measured in the lungs of rats exposed to traffic-related PM. Oxidative damage was observed. PM samples were taken from a near road site and an off road site in summer time in 2006. Results The concentrations of the USEPA priority pollutant PAHs in both PMlo and PM2.s were higher （299.658 and 348.412） at the near road site than those （237.728 and 268.472） at the off road site. The similar trend was observed for the concentrations of trace elements in PM. Compared to coarse particles （PM^0）, fine particles （PM2.s） have a greater adsorption capacity to enrich toxic elements than inhalable particles. Decrease in antioxidant capacity and an increase in the amount of lipid peroxidation products in rat lung tissues was observed. Conclusion The findings of the present study suggest that the differing inflammatory responses of PM collected from the two road sites might have been mediated by the differing physicochemical characteristics.展开更多
Formal health impact assessment (HIA), currently underused in the United States, is a relatively new process for assisting decision-makers in non-health sectors by estimating the expected public health impacts of poli...Formal health impact assessment (HIA), currently underused in the United States, is a relatively new process for assisting decision-makers in non-health sectors by estimating the expected public health impacts of policy and planning decisions. In this paper we quantify the expected air quality impacts of increased traffic due to a proposed new university campus extension in Chapel Hill, North Carolina. In so doing, we build the evidence base for quantitative HIA in the United States and develop an improved approach for forecasting traffic effects on exposure to ambient fine particulate matter (PM2.5) in air. Very few previous US HIAs have quantified health impacts and instead have relied on stakeholder intuition to decide whether effects will be positive, negative, or neutral. Our method uses an air dispersion model known as CAL3QHCR to predict changes in exposure to airborne, traffic-related PM2.5 that could occur due to the proposed new campus development. We employ CAL3QHCR in a new way to better represent variability in road grade, vehicle driving patterns (speed, acceleration, deceleration, and idling), and meteorology. In a comparison of model predictions to measured PM2.5 concentrations, we found that the model estimated PM2.5 dispersion to within a factor of two for 75% of data points, which is within the typical benchmark used for model performance evaluation. Applying the model to present-day conditions in the study area, we found that current traffic contributes a relatively small amount to ambient PM2.5 concentrations: about 0.14 μg/m3 in the most exposed neighborhood—relatively low in comparison to the current US National Ambient Air Quality Standard of 12 μg/m3. Notably, even though the new campus is expected to bring an additional 40,000 daily trips to the study community by the year 2025, vehicle-related PM2.5 emissions are expected to decrease compared to current conditions due to anticipated improvements in vehicle technologies and cleaner fuels.展开更多
The aerodynamic diameter of an air borne particle is the key property in determining its respiratory deposition. The study aim to assess PM2.5 level and its size distribution at 5 traffic junctions located along the l...The aerodynamic diameter of an air borne particle is the key property in determining its respiratory deposition. The study aim to assess PM2.5 level and its size distribution at 5 traffic junctions located along the lateral highway connected to NH-202. A cascade impactor has been used to measure the size function range of PM2.5 apart from PM10 of atmospheric dust particles in air being PM2.5 is concern with respect to effect on human health and is able to tend deeply into the respiratory tract reaching the lungs. It is observed that weight % of PM2.5 values are in the range of 40% - 60% of PM10 and few values of PM2.5 are exceeding the standards prescribed by CPCB. It is concluded that free flow of traffic is main concern and maintenance of road should be carried out during low traffic hours.展开更多
Studies were carried out to investigate the outdoor air pollution levels in vehicular traffic junctions in the major cities of Nsukka, Enugu and semi-urban area of Awgu all in Enugu State, Nigeria using standard analy...Studies were carried out to investigate the outdoor air pollution levels in vehicular traffic junctions in the major cities of Nsukka, Enugu and semi-urban area of Awgu all in Enugu State, Nigeria using standard analytical procedures. PM</span><sub><span style="font-family:Verdana;">2.5</span></sub><span style="font-family:Verdana;"> was collected using Envirotech air sampler, APM 550 and analyzed gravimetrically. Other determined air pollutant gases such as SO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">, NO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">, O</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;"> and CO were analyzed using colorimetric techniques. The mean hourly traffic density in the vehicular traffic junctions in Nsukka metropolis, Enugu metropolis and Awgu w</span></span><span style="font-family:Verdana;">ere</span><span style="font-family:""><span style="font-family:Verdana;"> 2015, 2873 and 587 respectively. The mean range of values of PM</span><sub><span style="font-family:Verdana;">2.5</span></sub><span style="font-family:Verdana;">, NO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">, SO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">, O</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;"> and CO in vehicular traffic junctions within the investigated environments w</span></span><span style="font-family:Verdana;">ere</span><span style="font-family:""><span style="font-family:Verdana;"> 1.67 - 12.16 μg/m</span><sup><span style="font-family:Verdana;">3</span></sup><span style="font-family:Verdana;">, 3.72 - 23.83 μg/m</span><sup><span style="font-family:Verdana;">3</span></sup><span style="font-family:Verdana;">, 2.96 - 30.09 μg/m</span><sup><span style="font-family:Verdana;">3</span></sup><span style="font-family:Verdana;">, 5.45 - 66.54 μg/m</span><sup><span style="font-family:Verdana;">3</span></sup><span style="font-family:Verdana;"> and 1.18 - 15.17 ppm respectively. The mean levels of the determined air pollutants in the air around vehicular traffic junctions in Nsukka metropolis, Enugu metropolis and Awgu semi-urban area differed significantly. The mean levels of PM</span><sub><span style="font-family:Verdana;">2.5</span></sub><span style="font-family:Verdana;">, and CO in the air around vehicular traffic junctions in Enugu metropolis and CO in the air around traffic junctions in Nsukka metropolis were above the recommended permissible limits. Traffic density was therefore seen as the single most important factor contributing to the varying air pollution levels observed in the investigated environments.展开更多
The recent year's monitor results of Beijing indicated that the pollution level of fine particles PM 2.5 showed an increasing trend. To understand pollution characteristics of PM 2.5 and its relationship...The recent year's monitor results of Beijing indicated that the pollution level of fine particles PM 2.5 showed an increasing trend. To understand pollution characteristics of PM 2.5 and its relationship with the meteorological conditions in Beijing, a one-year monitoring of PM 2.5 mass concentration and correspondent meteorological parameters was performed in Beijing in 2001. The PM 2.5 levels in Beijing were very high, the annual average PM 2.5 concentration in 2001 was 7 times of the National Ambient Air Quality Standards proposed by US EPA. The major chemical compositions were organics, sulfate, crustals and nitrate. It was found that the mass concentrations of PM 2.5 were influenced by meteorological conditions. The correlation between the mass concentrations of PM 2.5 and the relative humidity was found. And the correlation became closer at higher relative humidity. And the mass concentrations of PM 2.5 were negtive-correlated to wind speeds, but the correlation between the mass concentration of PM 2.5 and wind speed was not good at stronger wind.展开更多
To better understand the potential causes of visibility impairment in autumn and winter in Chengdu,relative humidity(RH),visibility,the concentrations of PM2.5 and its chemical components were on-line measured continu...To better understand the potential causes of visibility impairment in autumn and winter in Chengdu,relative humidity(RH),visibility,the concentrations of PM2.5 and its chemical components were on-line measured continuously in Chengdu from Nov.2016 to Jan.2017.Six obvious haze episodes occurred in Chengdu,with the total time of haze episodes accounted for more than 90%of the total observation period,and higher NO2 concentrations and RH were related to the high particle concentrations in haze episodes.The visibility decreased in a non-linear tendency under different RH conditions with the increase of PM2.5 concentrations,which was more sensitive to RH under lower PM2.5 concentrations.The threshold concentration of PM2.5 got more smaller with the increase of RH.During the entire observation period,organic matter(OM)was the largest contributor(31.12%to extinction coefficient(bext)),followed by NH4NO3 and(NH4)2SO4 with 28.03%and 23.01%,respectively.However,with the visibility impairment from Type I(visibility>10 km)to Type IV(visibility≤2 km),the contribution of OM to bextdecreased from 38.12%to 26.77%,while the contribution of NH4NO3 and(NH4)2SO4 to bextincreased from 19.09%and 20.20%to 34.29%and 24.35%,respectively,and NH4NO3 became the largest contributor to bextat Type IV.The results showed that OM and NH4NO3 were the key components of PM2.5 for visibility impairment in Chengdu,indicating that the control of precursors emissions of carbonaceous species and NH4NO3 could effectively improve the visibility in Chengdu.展开更多
Particle hygroscopicity plays a key role in understanding the mechanisms of haze formation and particle optical properties. The present study developed a method for predicting the effective hygroscopic parameter k and...Particle hygroscopicity plays a key role in understanding the mechanisms of haze formation and particle optical properties. The present study developed a method for predicting the effective hygroscopic parameter k and the water content of PM_(2.5) on the basis of the k-K?hler theory and bulk chemical components of PM_(2.5). Our study demonstrated that the effective hygroscopic parameter can be estimated using the PM_(2.5) mass concentration, water-soluble ions, and total water-soluble carbon. By combining the estimated k and ambient relative humidity, the water content of PM_(2.5) can be further estimated. As an example, the k and water content of PM_(2.5) in Beijing were estimated utilizing the method proposed in this study. The annual average value of k of PM_(2.5) in Beijing was 0.25±0.09, the maximum k value 0.26±0.08 appeared in summer, and the seasonal variation is insignificant. The PM_(2.5) water content was determined by both the PM_(2.5) hygroscopicity and the ambient relative humidity(RH). The annual average mass ratio of water content and PM_(2.5) was 0.18±0.20, and the maximum value 0.31±0.25 appeared in summer. Based on the estimated water content of PM_(2.5) in Beijing, the relationship between the PM_(2.5) water content and RH was parameterized as: m(%)=0.03+(5.73×10^(-8)) ×RH^(3.72).This parametric formula helps to characterize the relationship between the PM_(2.5) mass concentration and atmospheric visibility.展开更多
Recently,Chinese megacities have suffered serious air pollution.Previous studies have pointed out that transportation systems have become one of the major sources of air pollution and on-road pollutant concentrations ...Recently,Chinese megacities have suffered serious air pollution.Previous studies have pointed out that transportation systems have become one of the major sources of air pollution and on-road pollutant concentrations are significantly higher than off-road.Electric vehicle(EV)introduction is proposed as a method to alleviate the current situation.In order to better understand the benefit of the use of EVs in Beijing,a simulation platform has been developed to evaluate the improvement of air quality with the use of EVs quantitatively within the selected area.Four scenarios with different EV penetration rates are proposed and the results revealed 5%,10%,15%EV penetration rates which will bring about improvement of 0.86%,9.01%and 12.23%for PM2.5,0.92%,9.01%and 13.32%for nitrogen oxides(NO_(x)),0.95%,8.86%and 13.73%for CO,respectively.The results revealed a promising improvement of air quality with the introduction of EVs.展开更多
基金supported by the China Environmental Protection Administration (200709048)
文摘Objective Air-borne particulates from different sources could have different physicochemical properties and inflammatory potentials. This study aims to characterize the chemical compositions and the toxicity of ambient particulate matter （PM） associated with traffic emissions. Methods The concentrations of trace elements, organic carbon （OC）, elemental carbon （EC） and polycyclic aromatic hydrocarbons （PAHs） in PM2.5 and PMlo were measured in samples collected at sites in Beijing, China. Their toxic effects on the pulmonary system of rats were investigated. Biochemical parameters （LDH, T-AOC, TP） and inflammatory cytokine（IL-6, IL-1, TNF-a） levels were measured in the lungs of rats exposed to traffic-related PM. Oxidative damage was observed. PM samples were taken from a near road site and an off road site in summer time in 2006. Results The concentrations of the USEPA priority pollutant PAHs in both PMlo and PM2.s were higher （299.658 and 348.412） at the near road site than those （237.728 and 268.472） at the off road site. The similar trend was observed for the concentrations of trace elements in PM. Compared to coarse particles （PM^0）, fine particles （PM2.s） have a greater adsorption capacity to enrich toxic elements than inhalable particles. Decrease in antioxidant capacity and an increase in the amount of lipid peroxidation products in rat lung tissues was observed. Conclusion The findings of the present study suggest that the differing inflammatory responses of PM collected from the two road sites might have been mediated by the differing physicochemical characteristics.
文摘Formal health impact assessment (HIA), currently underused in the United States, is a relatively new process for assisting decision-makers in non-health sectors by estimating the expected public health impacts of policy and planning decisions. In this paper we quantify the expected air quality impacts of increased traffic due to a proposed new university campus extension in Chapel Hill, North Carolina. In so doing, we build the evidence base for quantitative HIA in the United States and develop an improved approach for forecasting traffic effects on exposure to ambient fine particulate matter (PM2.5) in air. Very few previous US HIAs have quantified health impacts and instead have relied on stakeholder intuition to decide whether effects will be positive, negative, or neutral. Our method uses an air dispersion model known as CAL3QHCR to predict changes in exposure to airborne, traffic-related PM2.5 that could occur due to the proposed new campus development. We employ CAL3QHCR in a new way to better represent variability in road grade, vehicle driving patterns (speed, acceleration, deceleration, and idling), and meteorology. In a comparison of model predictions to measured PM2.5 concentrations, we found that the model estimated PM2.5 dispersion to within a factor of two for 75% of data points, which is within the typical benchmark used for model performance evaluation. Applying the model to present-day conditions in the study area, we found that current traffic contributes a relatively small amount to ambient PM2.5 concentrations: about 0.14 μg/m3 in the most exposed neighborhood—relatively low in comparison to the current US National Ambient Air Quality Standard of 12 μg/m3. Notably, even though the new campus is expected to bring an additional 40,000 daily trips to the study community by the year 2025, vehicle-related PM2.5 emissions are expected to decrease compared to current conditions due to anticipated improvements in vehicle technologies and cleaner fuels.
文摘The aerodynamic diameter of an air borne particle is the key property in determining its respiratory deposition. The study aim to assess PM2.5 level and its size distribution at 5 traffic junctions located along the lateral highway connected to NH-202. A cascade impactor has been used to measure the size function range of PM2.5 apart from PM10 of atmospheric dust particles in air being PM2.5 is concern with respect to effect on human health and is able to tend deeply into the respiratory tract reaching the lungs. It is observed that weight % of PM2.5 values are in the range of 40% - 60% of PM10 and few values of PM2.5 are exceeding the standards prescribed by CPCB. It is concluded that free flow of traffic is main concern and maintenance of road should be carried out during low traffic hours.
文摘Studies were carried out to investigate the outdoor air pollution levels in vehicular traffic junctions in the major cities of Nsukka, Enugu and semi-urban area of Awgu all in Enugu State, Nigeria using standard analytical procedures. PM</span><sub><span style="font-family:Verdana;">2.5</span></sub><span style="font-family:Verdana;"> was collected using Envirotech air sampler, APM 550 and analyzed gravimetrically. Other determined air pollutant gases such as SO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">, NO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">, O</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;"> and CO were analyzed using colorimetric techniques. The mean hourly traffic density in the vehicular traffic junctions in Nsukka metropolis, Enugu metropolis and Awgu w</span></span><span style="font-family:Verdana;">ere</span><span style="font-family:""><span style="font-family:Verdana;"> 2015, 2873 and 587 respectively. The mean range of values of PM</span><sub><span style="font-family:Verdana;">2.5</span></sub><span style="font-family:Verdana;">, NO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">, SO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">, O</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;"> and CO in vehicular traffic junctions within the investigated environments w</span></span><span style="font-family:Verdana;">ere</span><span style="font-family:""><span style="font-family:Verdana;"> 1.67 - 12.16 μg/m</span><sup><span style="font-family:Verdana;">3</span></sup><span style="font-family:Verdana;">, 3.72 - 23.83 μg/m</span><sup><span style="font-family:Verdana;">3</span></sup><span style="font-family:Verdana;">, 2.96 - 30.09 μg/m</span><sup><span style="font-family:Verdana;">3</span></sup><span style="font-family:Verdana;">, 5.45 - 66.54 μg/m</span><sup><span style="font-family:Verdana;">3</span></sup><span style="font-family:Verdana;"> and 1.18 - 15.17 ppm respectively. The mean levels of the determined air pollutants in the air around vehicular traffic junctions in Nsukka metropolis, Enugu metropolis and Awgu semi-urban area differed significantly. The mean levels of PM</span><sub><span style="font-family:Verdana;">2.5</span></sub><span style="font-family:Verdana;">, and CO in the air around vehicular traffic junctions in Enugu metropolis and CO in the air around traffic junctions in Nsukka metropolis were above the recommended permissible limits. Traffic density was therefore seen as the single most important factor contributing to the varying air pollution levels observed in the investigated environments.
文摘The recent year's monitor results of Beijing indicated that the pollution level of fine particles PM 2.5 showed an increasing trend. To understand pollution characteristics of PM 2.5 and its relationship with the meteorological conditions in Beijing, a one-year monitoring of PM 2.5 mass concentration and correspondent meteorological parameters was performed in Beijing in 2001. The PM 2.5 levels in Beijing were very high, the annual average PM 2.5 concentration in 2001 was 7 times of the National Ambient Air Quality Standards proposed by US EPA. The major chemical compositions were organics, sulfate, crustals and nitrate. It was found that the mass concentrations of PM 2.5 were influenced by meteorological conditions. The correlation between the mass concentrations of PM 2.5 and the relative humidity was found. And the correlation became closer at higher relative humidity. And the mass concentrations of PM 2.5 were negtive-correlated to wind speeds, but the correlation between the mass concentration of PM 2.5 and wind speed was not good at stronger wind.
基金supported by Sichuan Science and Technology Program (Nos. 2018SZ0316, 2018SZDZX0023)the Research on Forecasting Technology of Heavy Pollution Weather
文摘To better understand the potential causes of visibility impairment in autumn and winter in Chengdu,relative humidity(RH),visibility,the concentrations of PM2.5 and its chemical components were on-line measured continuously in Chengdu from Nov.2016 to Jan.2017.Six obvious haze episodes occurred in Chengdu,with the total time of haze episodes accounted for more than 90%of the total observation period,and higher NO2 concentrations and RH were related to the high particle concentrations in haze episodes.The visibility decreased in a non-linear tendency under different RH conditions with the increase of PM2.5 concentrations,which was more sensitive to RH under lower PM2.5 concentrations.The threshold concentration of PM2.5 got more smaller with the increase of RH.During the entire observation period,organic matter(OM)was the largest contributor(31.12%to extinction coefficient(bext)),followed by NH4NO3 and(NH4)2SO4 with 28.03%and 23.01%,respectively.However,with the visibility impairment from Type I(visibility>10 km)to Type IV(visibility≤2 km),the contribution of OM to bextdecreased from 38.12%to 26.77%,while the contribution of NH4NO3 and(NH4)2SO4 to bextincreased from 19.09%and 20.20%to 34.29%and 24.35%,respectively,and NH4NO3 became the largest contributor to bextat Type IV.The results showed that OM and NH4NO3 were the key components of PM2.5 for visibility impairment in Chengdu,indicating that the control of precursors emissions of carbonaceous species and NH4NO3 could effectively improve the visibility in Chengdu.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41475127, 91544214)the National Basic Research Program of China (Grant No. 2013CB228503)+3 种基金the Strategic Priority Research Program of the China Academy of Sciences (Grant No. XDB05010500)the Special Fund of State Key Joint Laboratory of Environment Simulation and Pollution Control (Grant No. 14L02ESPC)the nonprofit research projects of Ministry of Environmental Protection, the People’s Republic of China (Grant No. 201409010)the Collaborative Innovation Center for Regional Environmental Quality
文摘Particle hygroscopicity plays a key role in understanding the mechanisms of haze formation and particle optical properties. The present study developed a method for predicting the effective hygroscopic parameter k and the water content of PM_(2.5) on the basis of the k-K?hler theory and bulk chemical components of PM_(2.5). Our study demonstrated that the effective hygroscopic parameter can be estimated using the PM_(2.5) mass concentration, water-soluble ions, and total water-soluble carbon. By combining the estimated k and ambient relative humidity, the water content of PM_(2.5) can be further estimated. As an example, the k and water content of PM_(2.5) in Beijing were estimated utilizing the method proposed in this study. The annual average value of k of PM_(2.5) in Beijing was 0.25±0.09, the maximum k value 0.26±0.08 appeared in summer, and the seasonal variation is insignificant. The PM_(2.5) water content was determined by both the PM_(2.5) hygroscopicity and the ambient relative humidity(RH). The annual average mass ratio of water content and PM_(2.5) was 0.18±0.20, and the maximum value 0.31±0.25 appeared in summer. Based on the estimated water content of PM_(2.5) in Beijing, the relationship between the PM_(2.5) water content and RH was parameterized as: m(%)=0.03+(5.73×10^(-8)) ×RH^(3.72).This parametric formula helps to characterize the relationship between the PM_(2.5) mass concentration and atmospheric visibility.
基金supported by the project“Research on the Traffic Environment Carrying Capacity and Feedback Gating Based Dynamic Traffic Control in Urban Network”which is funded by the China Postdoctoral Science Foundation with Grant no.2013M540102supported by the project“The research and application of the urban air environment regulation and control technology based on the Internet of Things”,which is under the State High-Tech Development Plan(The 863 program)+1 种基金funded by The Ministry of Science and Technology of the People’s Republic of China(Project No.2012AA063303)support for providing data and technology support.
文摘Recently,Chinese megacities have suffered serious air pollution.Previous studies have pointed out that transportation systems have become one of the major sources of air pollution and on-road pollutant concentrations are significantly higher than off-road.Electric vehicle(EV)introduction is proposed as a method to alleviate the current situation.In order to better understand the benefit of the use of EVs in Beijing,a simulation platform has been developed to evaluate the improvement of air quality with the use of EVs quantitatively within the selected area.Four scenarios with different EV penetration rates are proposed and the results revealed 5%,10%,15%EV penetration rates which will bring about improvement of 0.86%,9.01%and 12.23%for PM2.5,0.92%,9.01%and 13.32%for nitrogen oxides(NO_(x)),0.95%,8.86%and 13.73%for CO,respectively.The results revealed a promising improvement of air quality with the introduction of EVs.
