Estimation and validation of PM2.5/PM10 exhaust and non-exhaust emission factors for practical street pollution modelling

In order to carry out efficient traffic and air quality management, validated models and PM emission estimates are needed. This paper compares current available emission factor estimates for PM₁₀ and PM_2.5 from emission databases and different emission models, and validates these against eight high quality street pollution measurements in Denmark, Sweden, Germany, Finland and Austria.The data sets show large variation of the PM concentration and emission factors with season and with location. Consistently at all roads the PM₁₀ and PM_2.5 emission factors are lower in the summer month than the rest of the year. For example, PM₁₀ emission factors are in average 5–45% lower during the month 6–10 compared to the annual average.The range of observed total emission factors (including non-exhaust emissions) for the different sites during summer conditions are 80–130 mg km⁻¹ for PM₁₀, 30–60 mg km⁻¹ for PM_2.5 and 20–50 mg km⁻¹ for the exhaust emissions.We present two different strategies regarding modelling of PM emissions: (1) For Nordic conditions with strong seasonal variations due to studded tyres and the use of sand/salt as anti-skid treatment a time varying emission model is needed. An empirical model accounting for these Nordic conditions was previously developed in Sweden. (2) For other roads with a less pronounced seasonal variation (e.g. in Denmark, Germany, Austria) methods using a constant emission factor maybe appropriate. Two models are presented here.Further, we apply the different emission models to data sets outside the original countries. For example, we apply the “Swedish” model for two streets without studded tyre usage and the “German” model for Nordic data sets. The “Swedish” empirical model performs best for streets with studded tyre use, but was not able to improve the correlation versus measurements in comparison to using constant emission factors for the Danish side. The “German” method performed well for the streets without clear seasonal variation and reproduces the summer conditions for streets with pronounced seasonal variation. However, the seasonal variation of PM emission factors can be important even for countries not using studded tyres, e.g. in areas with cold weather and snow events using sand and de-icing materials. Here a constant emission factor probably will under-estimate the 90-percentiles and therefore a time varying emission model need to be used or developed for such areas.All emission factor models consistently indicate that a large part (about 50–85% depending on the location) of the total PM₁₀ emissions originates from non-exhaust emissions. This implies that reduction measures for the exhaust part of the vehicle emissions will only have a limited effect on ambient PM₁₀ levels.     

气浮-水解酸化-高效接触氧化工艺处理汽车废水

对某汽车公司的废水处理系统进行了改造,采用气浮-水解酸化-高效接触氧化工艺对其废水进行了处理,在水解酸化池中使用生物微电解填料,在接触氧化池内使用LK40弹性立体网状生物亲和性组合填料.经该体系处理后,出水水质为pH=6～9、SS＜60mg/L、CODCr＜90mg/L、BOD5＜20mg/L、石油类＜5mg/L,达到DB44/26-2001中一级标准,其处理费用为1.91元/m3.     

The use and safety of medications known to affect driving in Jordan: A cross-sectional study

Objectives: The aim of this study was to estimate the main driving-impairing medications used by drivers in Jordan, the reported frequency of medication side effects, the frequency of motor vehicle crashes (MVCs) while using driving-impairing medicines, as well as factors associated with MVCs.

Methods: A cross-sectional study involving 1,049 individuals (age 18–75 years) who are actively driving vehicles and taking at least one medication known to affect driving (anxiolytics, antidepressants, hypnotics, antiepileptics, opioids, sedating antihistamines, hypoglycemic agents, antihypertensives, central nervous system [CNS] stimulants, and herbals with CNS-related effects) was conducted in Amman, Jordan, over a period of 8 months (September 2013–May 2014) using a structured validated questionnaire.

Results: Sixty-three percent of participants noticed a link between a medicine taken and feeling sleepy and 57% stated that they experience at least one adverse effect other than sleepiness from their medication. About 22% of the participants reported having a MVC while on medication. Multiple logistic regression analysis showed that among the participants who reported having a crash while taking a driving-impairing medication, the odds ratios were significantly higher for the use of inhalant substance (odds ratio [OR] = 2.787, P = .014), having chronic conditions (OR = 1.869, P = .001), and use of antiepileptic medications (OR = 2.348, P = .008) and significantly lower for the use of antihypertensives (OR = 0.533, P = .008).

Conclusion: The study results show high prevalence of adverse effects of medications with potential for driving impairment, including involvement in MVCs. Our findings highlight the types of patient-related and medication-related factors associated with MVCs in Jordan, such as inhalant use, presence of chronic conditions, and use of antiepileptics.     

An empirical bayes safety evaluation of tram/streetcar signal and lane priority measures in Melbourne

Objective: Streetcars/tram systems are growing worldwide, and many are given priority to increase speed and reliability performance in mixed traffic conditions. Research related to the road safety impact of tram priority is limited. This study explores the road safety impacts of tram priority measures including lane and intersection/signal priority measures.

Method: A before–after crash study was conducted using the empirical Bayes (EB) method to provide more accurate crash impact estimates by accounting for wider crash trends and regression to the mean effects. Before–after crash data for 29 intersections with tram signal priority and 23 arterials with tram lane priority in Melbourne, Australia, were analyzed to evaluate the road safety impact of tram priority.

Results: The EB before–after analysis results indicated a statistically significant adjusted crash reduction rate of 16.4% after implementation of tram priority measures. Signal priority measures were found to reduce crashes by 13.9% and lane priority by 19.4%. A disaggregate level simple before–after analysis indicated reductions in total and serious crashes as well as vehicle-, pedestrian-, and motorcycle-involved crashes. In addition, reductions in on-path crashes, pedestrian-involved crashes, and collisions among vehicles moving in the same and opposite directions and all other specific crash types were found after tram priority implementation.

Conclusions: Results suggest that streetcar/tram priority measures result in safety benefits for all road users, including vehicles, pedestrians, and cyclists. Policy implications and areas for future research are discussed.     

系留气球垂直观测平台的构建与应用

利用1 600 m~3车载系留气球,构建大气复合型污染垂直观测平台。利用该平台对近地大气边界层的多种气象要素、多种污染物浓度水平及其物理化学特性进行高分辨的垂直测量,用以研究大气边界层的形成和演变及大气污染物垂直分布和变化特征、大气光化学过程的垂直变化以及污染物的区域输送。该平台以0.5 m/s的速度进行升降,于2013年12月在上海成功应用于大气污染垂直观测,观测中共获取大气污染物有效廓线50余组。利用观测数据,初步探索上海近地层复合型大气污染的生消机制及大气污染物垂直分布特征,为上海市空气污染预警和防控对策机制的制定提供技术支撑。     

怠速条件下汽车排气污染物在排气尾流中扩散特性的实验研究

通过实验的方法对怠速条件下汽车排气污染物在排气尾流中的扩散特性进行了研究.测定了怠速条件下汽车排气尾流中的污染物体积分数及其分布,并比较分析了3种不同类型汽车的污染物排放体积分数及其变化.实验结果表明,怠速时汽车排气尾流中的污染物体积分数按照近似指数函数的趋势迅速降低到接近大气背景值;不同类型汽车排气尾流中的污染物体积分数的差别非常明显;排气方向对汽车排放污染物的扩散及其分布具有重要的影响.研究工作可以为怠速工况下汽车排气污染物对周围环境的影响评价提供更多的有用信息.     

Field Evaluation of the PAS III Passive Alcohol Sensor

Passive alcohol sensors (PAS) are screening devices designed to sample nonintrusively the ambient air around a driver's mouth to determine the presence of alcohol. Studies have shown that PAS devices can aid police officers in the identification of unpaired drivers, particularly at sobriety checkpoints. Data from a 1996 nationwide survey, in which 5,392 drivers were evaluated for alcohol using both the PAS III (a passive sensor housed in a flashlight) and evidential breath test devices, have allowed the determination of appropriate criteria at various blood alcohol concentrations (BAC) for detecting impaired drivers in the field. Using the appropriate criteria, the PAS III can identify about 75% of the drivers with BACs at or above 0.10%, and 70% at or above 0.08%. This is a vast improvement over the 40-50% detection rate currently achieved by police officers at checkpoints not using sensors. Using the PAS III few drivers would be identified inappropriately. At the criterion recommended for detecting BACs at or above 0.08%, about 14% of drivers with BACs of 0.02-0.05% would be incorrectly identified as having a higher BAC. Field studies have shown that when police officers rely on observation alone about 20% of drivers with low BACs are detained for further evaluation. More widespread use of passive sensors by police officers would aid in the detection of drinking drivers. Sensors also could provide an additional deterrent to the general public if they believe that when stopped by the police after drinking they will be detained for further evaluation.     

Age Dependence of Female to Male Fatality Risk in the Same Crash: An Independent Reexamination

A 1988 study reported that females are more likely than males to be killed by the same physical insult. This was determined by analyzing 1975–1983 data. The present study revisits this question using 123,678 fatalities from 1984–1996 data. As none of these data contributed to the earlier study, the present investigation is therefore independent of the earlier one. Female to male fatality risk ratios are calculated for 14 categories of vehicle occupants, including six light truck occupants (belted and unbelted drivers and right front passengers, and unbelted left and right rear passengers). The earlier study did not include light trucks. Close agreement is found between the results of the present and prior studies, thus solidifying the interpretation that findings are of a general nature and not dependent on specific data sets. Except at ages less than about 10 years, or older than about 55, females are more likely to be killed than males. While obtained using traffic data, the results are interpreted to reflect fundamental differences in human physiological response to blunt trauma in general, and are expected to apply to blunt trauma from falls, being struck by objects, etc.