Functional outcomes of motor vehicle crash thoracic injuries in pediatric and adult occupants

Objective: Characterization of the severity of injury should account for both mortality and disability. The objective of this study was to develop a disability metric for thoracic injuries in motor vehicle crashes (MVCs) and compare the functional outcomes between the pediatric and adult populations.

Methods: Disability risk (DR) was quantified using Functional Independence Measure (FIM) scores within the National Trauma Data Bank for the most frequently occurring Abbreviated Injury Scale (AIS) 2–5 thoracic injuries. Occupants with thoracic injury were classified as disabled or not disabled based on the FIM scale, and comparisons were made between the following age groups: pediatric, adult, middle-aged, and older occupants (ages 7–18, 19–45, 46–65, and 66+, respectively). For each age group, DR was calculated by dividing the number of patients who were disabled and sustained a given injury by the number of patients who sustained a given injury. To account for the effect of higher severity co-injuries, a maximum AIS adjusted DR (DR_MAIS) was also calculated for each injury. DR and DR_MAIS could range from 0 to 100% disability risk.

Results: The mean DR_MAIS for MVC thoracic injuries was 20% for pediatric occupants, 22% for adults, 29% for middle-aged adults, and 43% for older adults. Older adults possessed higher DR_MAIS values for diaphragm laceration/rupture, heart laceration, hemo/pneumothorax, lung contusion/laceration, and rib and sternum fracture compared to the other age groups. The pediatric population possessed a higher DR_MAIS value for flail chest compared to the other age groups.

Conclusion: Older adults had significantly greater overall disability than each of the other age groups for thoracic injuries. The developed disability metrics are important in quantifying the significant burden of injuries and loss of quality life years. Such metrics can be used to better characterize severity of injury and further the understanding of age-related differences in injury outcomes, which can influence future age-specific modifications to AIS.     

京津冀地区一次浮尘过程的车载激光雷达走航观测

利用双波长三通道激光雷达与车载激光雷达,针对2018年3月28日京津冀区域的浮尘天气过程,分别进行了定点垂直观测与车载走航观测,对这次浮尘天气中沙尘的源地、沙尘气溶胶的时空分布、沙尘的传输路径与传输方式进行了综合分析。位于北京的激光雷达监测到28日凌晨开始,沙尘气溶胶与近地面污染物混合,受沙尘影响近地面污染物浓度迅速升高。北京到沧州的车载激光雷达走航观测结果显示,沙尘气溶胶先向南传输到京津冀南部区域,随后向西南方向传输,同时观测到京津冀区域上空1. 5 km左右存在沙尘传输带。结果表明,使用车载激光雷达走航观测,结合定点垂直激光雷达与其他地面监测数据,能可靠地观测到沙尘过程中颗粒物的时空变化特征。     

Driving difficulties as reported by older drivers with mild cognitive impairment and without neurological impairment

Objective: Considerable evidence indicates that medical conditions prevalent among older individuals lead to impairments in visual, cognitive, or psychomotor functions needed to drive safely. The purpose of this study was to explore the factors determining driving difficulties as seen from the viewpoint of 30 older drivers with mild cognitive impairment (MCI) and 30 age-matched controls without cognitive impairment.

Methods: Perceptions of driving difficulties from both groups were examined using data from an extensive questionnaire. Samples of drivers diagnosed with MCI and age-matched controls were asked to report the frequency with which they experienced driving difficulties due to functional deficits and knowledge of new traffic rules and traffic signs.

Results: The analysis revealed that 2 factors underlie MCI perceptions of driving difficulties, representing (1) difficulties associated with late detection combined with slowed response to relevant targets in the peripheral field of view and (2) difficulties associated with divided attention between tasks requiring switching from automatic to conscious processing particularly of long duration. The analysis for healthy controls revealed 3 factors representing (1) difficulties in estimating speed and distance of approaching vehicles in complex (attention-dividing) high-information-load conditions; (2) difficulties in moving head, neck, and feet; and (3) difficulties in switching from automatic responses to needing to use cognitive processing in new or unexpected situations.

Conclusions: Though both group analyses show difficulties with switching from automatic to decision making, the difficulties are different. For the control group, the difficulty in switching involves switching in new or unexpected situations associated with high-information-load conditions, whereas this switching difficulty for the MCI group is associated with divided attention between easier tasks requiring switching. These findings underline the ability of older drivers (with MCI and without cognitive impairment) to indicate probable impairments in various driving skills. The patterns of difficulties perceived by the MCI group and the age-matched healthy control group are indicative of demanding driving situations that may merit special attention for road designers and road safety engineers. They may also be considered in the design of older drivers’ fitness to drive evaluations, training programs, and/or vehicle technologies that provide for older driver assistance.     

Continued trends in older driver crash involvement rates in the United States: Data through 2017–2018

Introduction: With the growing older adult population due to the aging baby-boom cohort, there was concern that increases in fatal motor-vehicle crashes would follow. Yet, previous analyses showed this to be untrue. The purpose of this study was to examine current trends to determine if previous declines have persisted or risen with the recent increase in fatalities nationwide. Methods: Trends among drivers ages 70 and older were compared with drivers 35–54 for U.S. passenger vehicle fatal crash involvements per 100,000 licensed drivers from 1997 to 2018, fatal and all police-reported crash involvements per vehicle miles traveled using the 1995, 2001, 2009, and 2017 National Household Travel Surveys, and driver deaths per 1,000 crashes. Results: Since the mid-1990s, fatal crashes per licensed driver trended downward, with greater declines for drivers ages 70 and older than for middle-aged drivers (43% vs. 21%). Fatal crash rates per 100,000 licensed drivers and police-reported crash rates per mile traveled for drivers ages 70–79 are now less than those for drivers ages 35–54, but their fatal crash rates per mile traveled and risk of dying in a crash remain higher as they drive fewer miles. As the economy improved over the past decade, fatal crash rates increased substantially for middle-aged drivers but decreased or remained stable among older driver age groups. Conclusions: Fatal crash involvements for adults ages 70 and older has recently increased, but they remain down from their 1997 peak, even as the number of licensed older drivers and the miles they drive have increased. Health improvements likely contributed to long-term reductions in fatal crash rates. As older drivers adopt vehicles with improved crashworthiness and safety features, crash survivability will improve. Practical Application: Older adults should feel confident that their independent mobility needs pose less risk than previously expected.     

Adaptation of a Canadian culpability scoring tool to Alberta police traffic collision report data

Objective: The objective of this study was to adapt a previously validated Canadian Culpability Scoring Tool (CCST) to Alberta police report data.

Methods: Police traffic collision reports from motor vehicle (MV) collisions in Calgary and Edmonton (Alberta, Canada) from 2010 to 2014 were used. Adaptation of the CCST was completed with input from personnel within Alberta Transportation, contributing to face and content validity. Two research assistants, given only the information necessary for scoring, evaluated 175 randomly selected MV–MV collisions. Interrater agreement was estimated using kappa (k) and reported with 95% confidence intervals (CIs). Discussion of disagreements between the research assistants and consultation from Alberta Transportation informed the algorithm used in the Alberta Motor Vehicle Collision Culpability Tool (AMVCCT). The AMVCCT was automated and applied to all motorists involved in collisions. Binary logistic regression was used to examine characteristics of the culpable and nonculpable drivers and their effects were reported using odds ratios (ORs) with 95% CIs.

Results: Interrater agreement for the random sample was excellent (k = 0.95; 95% CI, 0.92–0.99). Of those drivers hospitalized, 1,130 (37.54%) were rated not culpable and 1,880 (62.46%) were rated culpable. The odds of being culpable were higher for males than for females (OR = 1.43; 95% CI, 1.23–1.66). The odds of being culpable were higher in those impaired by alcohol than those considered “apparently normal” (OR = 61.10; 95% CI, 22.66–164.75). The odds of being deemed culpable, when compared with drivers >54 years old, were higher for those <25 years old (OR = 1.72; 95% CI, 1.35–2.20) and lower for those in the 40- to 54-year-old age group (OR = 0.78; 95% CI, 0.63–0.96). Driving between 12 a.m. and 6 a.m. resulted in higher odds of being culpable compare with all other 6-h time blocks. Direction and statistical significance remained consistent when applying the tool to all MV collisions. Sensitivity analysis including the removal of single vehicle collisions did not affect the direction or statistical significance of the main results.

Conclusions: The AMVCCT identified a culpable group that exhibited characteristics expected in drivers who are at fault in collisions. The age groups 25–39 and 40–54 demonstrated different results than the CCST. However, this is the only difference that exists in the findings of the AMVCCT compared to the CCST and could exist due to differences between the driving populations in Alberta and British Columbia. It is possible to adapt the CCST to provinces outside British Columbia and, in doing so, we can identify risk factors for collision contribution and not-at-fault drivers who represent the driving population.     

水幕与排烟系统协作下隧道火灾烟气防控研究

为优化选择水幕和机械排烟系统作用下最佳防排烟方式，运用FDS数值模拟方法探究排烟速率和水幕与排烟口间距对烟流分布的影响，并对11组模拟工况下排烟效率和烟气特征参数变化规律进行研究。结果表明:20 MW的火源功率下，排烟速率为60 m3/s、水幕与排烟口间距为12.5 m时，排烟效率较高且烟气特征参数满足安全要求，考虑防排烟的有效性和经济性，可选其为最优防排烟组合方式。研究结果对防排烟系统的设计具有指导意义。     

京津冀地区机动车细颗粒物污染的健康影响分析

机动车尾气排放对城市空气污染的影响日益严峻，而对特定污染源大气污染排放特征及健康影响进行评估可以为环境空气质量管理提供科学依据.以PM_2.5为研究对象，分析京津冀地区2010～2020年机动车污染排放特征、导致的健康效应与经济损失.结果表明，2010～2020年间京津冀地区机动车PM_2.5排放量呈现先逐年递增后缓慢下降的趋势；不同车型污染物排放贡献率显示，重型货车和重型客车为PM_2.5主要贡献车型；不同城市机动车污染物排放特征存在差异，北京市污染物贡献率下降幅度明显，其余城市污染减排也不容忽视.机动车PM_2.5污染对人群健康影响的评估结果表明，京津冀地区各健康终端发生人数总体呈上升趋势，其中，2020年PM_2.5污染造成约34 337人(95%CI:9 025～57 209人)早逝、4.55万人(95%CI:1.08～8.02万人)住院、 28.23万人(95%CI:14.05～41.63万人)门诊及43.90万人(95%CI:16.03～67.92万人)患病；研究期间(201...     

基于IVE模型乌鲁木齐机动车大气污染物排放因子研究

本文通过对乌鲁木齐市主城区机动车车型、燃料和运行工况的信息调查,得到主城区机动车现状.在此基础上,采用IVE模型进行模拟,结合统计分析,计算得到了2010年乌鲁木齐市主城区机动车基于行驶里程的启动和运行排放因子.将有助于掌握乌鲁木齐市主城区机动车技术状况、车龄分布、年均行驶里程、在路行驶车型比例以及各型在用机动车排放状况,为制定主城区机动车排气污染管理措施,改善大气环境质量提供科学依据.     

Variation characteristics of fine particulate matter and its components in diesel vehicle emission plumes

A rapid reaction occurs near the exhaust nozzle when vehicle emissions contact the air. Twenty diesel vehicles were studied using a new multipoint sampling system that is suitable for studying the exhaust plume near the exhaust nozzle. The variation characteristics of fine particle matter (PM_2.5) and its components in diesel vehicle exhaust plumes were analyzed. The PM_2.5 emissions gradually increased with increasing distance from the nozzle in the plume. Elemental carbon emissions remained basically unchanged, organic carbon and total carbon (TC) increased with increasing distance. The concentrations of SO₄^2?, NO₃^? and NH₄⁺ (SNA) directly emitted by the vehicles were very low but increased rapidly in the exhaust plume. The selective catalytic reduction (SCR) reduced 42.7% TC, 40% NO₃^? emissions, but increased 104% SO₄^2? and 36% NH₄⁺ emissions, respectively. In summary, the SCR reduced 29% primary PM_2.5 emissions for the tested diesel vehicles. The NH₄NO₃ particle formation maybe more important in the plume, and there maybe other forms of formation of NH₄⁺ (eg. NH₄Cl). The generation of secondary organic carbon (SOC) plays a leading role in the generation of secondary PM_2.5. The SCR enhanced the formation of SOC and SNA in the plume, but comprehensive analysis shows that the SCR more enhanced the SNA formation in the plume, which is mainly new particles formation process. The inconsistency between secondary organic aerosol (SOA) and primary organic aerosol definitions is one of the important reasons for the difference between SOA simulation and observation.