Exploring the effect of air pollution on settlement intentions from migrants: Evidence from China

Based on the China Migrants Dynamic Survey (CMDS) from 2015 to 2017, this paper uses IV-Probit model to investigate the effects of air pollution on migrants' settlement intentions in China. The results show that: First, air pollution has a significant and negative effect on intentions in settling down of the migrants. Specifically, when the concentration of PM_2.5 increases by 1 μg/m³, the probability of migrants settling down in the city which they have moved to for work or business will significantly decrease by 1.89%. Second, there is heterogeneity in the effects of air pollution on migrants' settlement intentions. In detail, the sensitivity to air pollution is higher among female groups, who have higher education levels and prefer better air quality in the living place to settle down, and there is an inverted U-shaped relationship between age and settlement intentions. On the one hand, the conclusion of this paper enriches the relevant theoretical achievements of air pollution and migration. On the other hand, it also has a high reference value for developing more reasonable policies related to urban environmental governance and labor mobility.     

宝鸡市大气环境污染特征分析

以宝鸡市“九五”期间的大气环境监测数据为基础,详细论述了大气污染特征及其产生的原因,并针对大气环境存在的主要问题,提出了市区大气污染防治对策。     

Understanding Urban Vehicular Pollution Problem Vis-a-Vis Ambient Air Quality – Case Study of a Megacity (Delhi, India)

Air pollution has become a growing problem in megacities and large urban areas through out the globe, and transportation is recognized as the major source of air pollution in many cities, especially in developing countries. Contribution of automobiles is reported in the range of 40 to 80% of the total air pollution. The challenge facing megacities is how to reduce the adverse environmental impacts and other negative effects of transportation without giving up the benefits of mobility. The dilemma becomes most pressing under conditions of rapid urban growth, which is likely to increase travel demand significantly.The paper is aimed at understanding the problem of vehicular pollution vis-a-vis ambient air quality for a highly traffic affected megacity, Delhi, wherein, the contribution of transport sector was estimated to be as high as 72%. An effort has been made to review and evaluate the benefits (in terms of improved air quality) of the technological interventions/policies adopted for vehicular pollution control in Delhi. It also highlights the outcome of the efforts and suggests further improvements thereon. The importance of public participation and awareness are also discussed. The paper focuses on deriving the benefits of the implementation of management strategies, supported by scientific and technical data/interpretation, so that the people can realize and participate in the government's endeavor for clean city drive in a more effective manner.     

洛阳市大气污染特征与相关气象要素24小时变化分析

通过对洛阳市环境空气监测资料的统计,归纳出洛阳市区日内24小时环境空气污染变化特征,并结合同步气象观测资料综合分析,找出了二者之间的联系特征。引入气温日较差这一便于观测、预报的气象要素表征空气污染物垂直扩散特征,为今后进行污染预报提供了新的思路。     

Assessment of Urban Air Quality in South Estonia by Simple Measures

In countries having limited resources, it is difficult to assess urban air quality on contemporaneously, due to the absence of on-line information about air pollution levels and emission rates. An alternative approach is recommended for smaller cities with lower demands of resources. The applied scheme consists of a database of air pollution sources (NO _x and CO from industry, traffic, and domestic heating), the simple Gaussian-plume model AEROPOL and a series of measurements by passive monitors. This method was used in Tartu, a small city situated in the valley of the river Emajõgi, within a landscape with noteworthy topographical variations. Simulations of annual average and maximal concentrations were performed, and a fair agreement obtained with NO₂ monitoring results from passive Palmes monitors. Inventories of pollution sources in 1998 revealed that official statistics of stationary sources covered 64% of SO₂,36% of CO, 37% of NO _x and 32% of total particulate matter emissions. Recommendations for measures for reducing air pollution levels and for further investigations towards improving air quality assessment and management, are given.     

BIOMONITORING OF AIR POLLUTION IN A SEASONALLY DRY TROPICAL SUBURBAN AREA USING WHEAT TRANSPLANTS

Air pollution has been identified as a serious problem throughout the world which causes tremendous loss to the crops by affecting plant growth and yield. Earlier, air pollution was restricted to urban and industrial regions. Over the last few decades, however, it has become evident that pollutants can be transported over long distances and hence their impact may be felt widely over rural areas. The present study was conducted to evaluate the impact of urban air pollution on suburban agriculture with respect to the changes in photosynthetic rate, stomatal conductance, water-use efficiency, plant height, numbers of tillers, leaves, ears and seeds, chlorophyll, carotenoid, protein, phenol, ascorbic acid, nitrogen and sulphate-sulphur contents and seed weight of pot-grown wheat plants (Triticum aestivum var. HUW 468) kept at different sites around Varanasi city receiving varying levels of pollution load. Mean concentrations of were monitored. The study clearly showed that plants are negatively affected by the ambient levels of air pollutants. Reduction in various parameters directly corresponded with the air pollution levels at different sites.     

Spatial variability of air pollutants in the city of Taranto, Italy and its potential impact on exposure assessment

Epidemiological studies typically use monitored air pollution data from a single station or as averaged data from several stations to estimate population exposure. In industrialized urban areas, this approach may present critical issues due to the spatial complexities of air pollutants which are emitted by different sources. This study focused on the city of Taranto, which is one of the most highly industrialized cities in southern Italy. Epidemiological studies have revealed several critical situations in this area, in terms of mortality excess and short-term health effects of air pollution. The aims of this paper are to study the variability of air pollutants in the city of Taranto and to interpret the results in relation to the applicability of the data in assessing population exposure. Meteorological and pollution data (SO2, NO2, PM10), measured simultaneously and continuously during the period 2006–2010 in five air quality stations, were analyzed. Relative and absolute spatial concentration variations were investigated by means of statistical indexes. Results show significant differences among stations. The highest correlation between stations was observed for PM10 concentrations, while critical values were found for NO2. The worst values were observed for the SO2 series. The high values of 90th percentile of differences between pairs of monitoring sites for the three pollutants index suggest that mean concentrations differ by large amounts from site to site. The overall analysis supports the hypothesis that various parts of the city are differently affected by the different emission sources, depending on meteorological conditions. In particular, analysis revealed that the influence of the industrial site may be primarily identified with the series of SO2 data which exhibit higher mean concentration values and positive correlations with wind intensity when the monitoring station is downwind from the industrial site. Results suggest evaluating the population exposure to air pollutants in industrialized cities by taking into account the possible zones of influence of different emission sources. More research is needed to identify an indicator, which ought to be a synthesis of several pollutants, and take into account the meteorological variables.     

Efficient control of air pollution through plants, a cost-effective alternative: studies on Dalbergia sissoo Roxb

Plants can be used as both passive biomonitors and biomitigators in urban and industrial environments to indicate the environmental quality and to ameliorate pollution level in a locality. Many studies reveal that plants are negatively affected by the ambient levels of air pollutants. The present study was conducted to evaluate the impact of air pollution on comparative basis with reference to changes in photosynthetic pigments, plant height, leaves, as well as, biochemical parameters of plants of different sites around Udaipur city receiving varying levels of pollution load. The investigated tree species Dalbergia sissoo Roxb. (Family: Fabaceae) exhibited a reduction in various physiological and biochemical growth parameters that correspond with air pollution levels at different sites. The tree species growing in polluted and control areas were compared with respect to foliar dust load, leaf area, and chlorophyll and total carbohydrate and total protein concentration in the leaves. Our studies suggest that D. sissoo Roxb. can successfully be grown in an area for monitoring air pollution, where it is mild and droughts are common. It will prove as an ideal tree species to control pollution effectively beside acting as a shade tree and being a source of food for birds and animals. By plantation of D. sissoo Roxb., mitigative measure at the polluted sites to control generation of particulate matter and the air quality required can be ensured. Our results also confirm that industrial and vehicular air pollution level in Udaipur city is shifting beyond limits.     

Evaluation of air pollution phytotoxicity in a seasonally dry tropical urban environment

This study was conducted in the urban environment of Varanasi, India, to evaluate the plant responses to urban air pollution. Twenty sites were selected in four different zones of the city. At each site, seven woody perennials of same age classes were selected. Out of the four zones (I, II, III and IV), zone IV was used as a reference (control) zone as it received the minimum pollution input. Plant species growing in polluted and control areas were compared with respect to foliar dust load, per cent leaf area injury, leaf area, specific leaf weight and chlorophyll, ascorbic acid, SO ₄ ^2– S and total N concentration in the leaves. Results indicated that the air pollution level in Varanasi causes leaf damage, reduces leaf area, specific leaf weight and chlorophyll, ascorbic acid and total N concentrations in the leaves. Sulphur concentration in leaves increased with increasing level of SO₂ in the ambient air. The magnitude of such changes was maximum at the zone receiving maximum pollution load. Carissa carandas was found to be the most sensitive species and Bougainvillea spectabilis, the least. The study shows that the urban air pollution level in Varanasi is detrimental for the growth of plants involved in this study.     

扬州地区酸雨现状及成因分析

根据2006年1月—2010年12月的酸雨监测数据,对扬州地区酸雨的变化规律和趋势进行了统计分析。结果表明:扬州地区酸雨主要集中在扬州市区与仪征城区,"十一五"期间,扬州市区酸雨呈逐年减少趋势,仪征城区大气污染严重,降水pH年均值均小于5.6,经评价扬州市区属于非酸雨区-较重酸雨区,仪征城区属于轻酸雨区-重酸雨区。高邮、江都、宝应城区从2007年起无酸雨出现。仪征城区酸雨主要是由燃煤型和燃油型混合空气污染造成的,近年来随着机动车拥有量的迅速增加,各种机动车排放的尾气已成为形成酸雨的重要原因,应引起重视。     

The potential of biomonitoring of air quality using leaf characteristics of white willow (Salix alba L.)

In this study, we assess the potential of white willow (Salix alba L.) as bioindicator for monitoring of air quality. Therefore, shoot biomass, specific leaf area, stomatal density, stomatal pore surface, and stomatal resistance were assessed from leaves of stem cuttings. The stem cuttings were introduced in two regions in Belgium with a relatively high and a relatively low level of air pollution, i.e., Antwerp city and Zoersel, respectively. In each of these regions, nine sampling points were selected. At each sampling point, three stem cuttings of white willow were planted in potting soil. Shoot biomass and specific leaf area were not significantly different between Antwerp city and Zoersel. Microclimatic differences between the sampling points may have been more important to plant growth than differences in air quality. However, stomatal pore surface and stomatal resistance of white willow were significantly different between Zoersel and Antwerp city. Stomatal pore surface was 20% lower in Antwerp city due to a significant reduction in both stomatal length (?11%) and stomatal width (?14%). Stomatal resistance at the adaxial leaf surface was 17% higher in Antwerp city because of the reduction in stomatal pore surface. Based on these results, we conclude that stomatal characteristics of white willow are potentially useful indicators for air quality.     

Urban Development and Air Quality in San Luis City, Argentina

Some factors such as the high population growth, along with insufficient housing, health and sanitary services, obsolete industrial technology and the lack of environmental management programs, give rise to contamination in Latin-American cities. Owing to the urban characteristics of San Luis, a detailed analysis of air quality was planned as part of a more comprehensive study, in order to make an environmental diagnosis of the city after the demographical and economic upgrowth over the last 15 years. It has been concluded that air pollution levels in San Luis are higher than those expected for a medium-size city. The reported high levels were attributed to important industrial activity, responsible not only for the direct of polluting gases to the atmosphere but also as the principal cause of the urban expansion. The levels of CO and SO₂ (ppm) found in the city can be considered as high. Some weeks during the sampling measure values were appreciably higher than the maximum tolerance levels established. The urban area under study was separated into five defined areas, which allowed to make comparisons in order to identify specific contamination problems. The slopes corresponding to the plot polluting substances concentration vs. wind speed were lower than the expected values. Because of the urban area characteristics, different micrometeorological effects facilitating a low air exchange can be generated, and consequently increasing the contamination levels. Thus, it is correct to conclude that the degradation processes are not occurring in a single environmental plane. Accordingly, air contamination rate in San Luis city could be considered as evidence of other upper-scale regional environmental degradation processes.     

Erroneous mass transit system and its tended relationship with motor vehicular air pollution (An integrated approach for reduction of urban air pollution in Lahore)

Air pollution is threat to the lives of people living in big cities of Pakistan. In Lahore 1,250 people die annually because of air pollution.Mass transit system that can be put forth as solution to urban air pollution is contingent with right choice of system and its affiliation with motorized vehicles and nature of urban air pollution.Existing mass transit system in Lahore due to untrue operation causes surfeit discharge of motor vehicular carbon monoxide. Tended relationships of mass transit system with motorized vehicles and urban air pollution are quite noteworthy. The growing motor vehicles (a consequence of flawed public mass transit system) are potential source of urban air pollution. This paper attempts to highlight correlations and regression curves of existing mass transit system. Further it recommends a two facet approach for reduction of motor vehicular air pollution in Lahore.     

乌鲁木齐市城市环境综合整治定量考核初步研究

城市环境综合整治定量考核是中国为保护和改善城市环境质量而实行的一种行政性管理制度。该项制度目前采用20项指标,综合衡量一个城市的环境质量等级,并进行城市间的相互比较。乌鲁木齐市自1989年参加城考以来,成绩一直不理想,特别是环境空气质量得分不理想。本文采用通常方案和减排方案对2008年城考结果进行预测。结果表明,只有采取减排方案,才能改变乌鲁木齐市在全国城考中排名落后的状况。     

乌鲁木齐大气微生物污染研究

采用网格布点用自然沉降法同步采样，调查和研究乌鲁木齐建成区大气微生物浓度分布、污染现状及微生物污染类型特征．结果表明：乌鲁木齐市大气微生物以细菌为主导，占微生物总数的７９．５％，真菌约占２０．５％．建成区大气微生物达５级中污染水平．大气微生物污染分布与环境条件和环境质量都有一定关系。     

On the horizontal homogeneity of mass-related aerosol properties

We studied the mass-related aerosol properties, simultaneously attwo sites at the urban roof top level in the same city. Nosystematic influence of the wind vector on the difference in theaerosol concentrations between the two locations could be found.These results are compared with results from a second, similarexperiment over a larger distance including one urban and onerural site. Surprisingly, we could not detect a tendency whichwould indicate that sampling air at distance in the order of 1 kmwould be less affected by the heterogeneity than samplingdistanced in the order of 10 km apart. On the contrary, theresults suggest that mass-related properties at two sites in thesame city are not necessarily more similar than at an urban and arural site outside the city. These results stress the limitedhorizontal homogeneity of urban atmospheric aerosol. As aconclusion it is suggested that single-site measurements of mass-related aerosol properties should be considered to berepresentative for an area smaller than 1 km² on size.     

A GIS-based Study for Optimizing the Total Emission Control Strategy in Lanzhou City

A geographic information system (GIS)-based approach with spatial analysis advantages was developed to optimize the total emission control scheme on air pollution in Lanzhou, combined with Models-3 modeling system and a linear programming model. GIS system is mainly used for establishing a multifactor assessment model to quantitatively divide environmental functional zone, and also used for selecting control sites in linear programming model. The results show that most of the urban area belongs to the second type of function, which is 122.8 km² occupying about 76.5% and the third type of about 32.9 km² occupying 20.5%. To reach the air quality up to the national standard in the entire control area, some large-emission factories need to cut emissions from 19% to 27%. For small but low-emission height sources, the cut may be as high 40%. The improvement of the ecological environment is urgently needed for controlling the background particle pollution in Lanzhou city.     

Speciation and sources of atmospheric aerosols in a highly industrialised emerging mega-city in central China

Monitoring air quality in large urban agglomerations is the key to the prevention of air pollution-related problems in emerging mega-cities. The city of Wuhan is a highly industrialised city with >9 million inhabitants in Central China. Simultaneous PM10 sampling was performed during 1 year at one urban and one industrial site. Mean PM10 daily levels (156 microg m(-3) at the urban site and 197 microg m(-3) at the industrial hotspot) exceed the US-EPA or EU annual limit values by 3-4 times. A detailed study of daily speciation showed that the mean chemical composition of PM10 presents minimal differences between peak and low PM episodes. This implies that PM10 aerosols in the study area result from local emissions, and air quality management and abatement strategies in Wuhan should thus focus on local anthropogenic sources. The levels of some elements of environmental concern are relatively high (409-615 ngPb m(-3), 66-70 ngAs m(-3), 116-227 ngMn m(-3), 10-12 ngCd m(-3)) due to industrial, but also urban emissions. Principal component analysis identified a mineral source (probably cement and steel manufacture) and smelting as the main contributors to PM10 levels at the industrial site (34%), followed by a coal fired power plant (20%) and the anthropogenic regional background (16%). At the urban site the major PM10 source is a mixed coal combustion source (31%), followed by the anthropogenic regional background (28%) and traffic (16%).     

米泉市城市环境空气污染状况分析和污染防治对策探析

根据2000年以来的环境监测数据,分析新疆首府乌鲁木齐市的重要卫星城米泉市的环境空气污染状况,结果显示米泉市环境空气质量污染严重,超越乌鲁木齐市。成为全疆冬季大气污染最严重的城市之一,大气环境质量亟待改善。本文针对米泉市环境空气严重污染的状况提出了控制对策和减缓措施,以期为改善乌鲁木齐市及周边城市大气污染状况提供依据。     

天水市空气微生物含量分析

用平皿沉降法测定了天水市空气微生物含量,结果证实其空气细菌、真菌及总菌的平均含量分别为5312.3、13．1和5325．4CFU／m3．空气真菌占总菌量的0．2％左右,空气微生物以细菌为主十分明显,所测风景区空气细菌含量与城区的平均水平间差异很大,说明天水市空气已受到较轻的中度污染,闹市区的一些测点空气污染已相当严重。