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Requiring manufacturers to manage their products when they become waste is an innovative form of regulation, one that has been adopted by countries in Asia, Europe, and North America on a variety of products that range from vehicles to appliances to batteries. However, even in many unregulated industries, some manufacturers are voluntarily assuming more responsibility for their end-of-life products, driven by customer demand and cost efficiencies. This article explores various forms of take-back regulation and highlights some of the key features of the institutions that emerge in response. In addition, it presents seven strategic product recovery alternatives, followed by a discussion of some factors managers should consider in developing a take-back strategy. INSETS: Major Product Take-Back Bills introduced into U.S. State...;RosettaNet. [ABSTRACT FROM AUTHOR]

Policies protecting children from exposure to secondhand smoke (SHS) may help prevent SHS-related negative health outcomes in children and discourage them from intending to smoke in the future. In this study, we assess the impact of California's 2007 smoke-free vehicle law on changes in middle and high school students' reported exposure to smoking in cars. Secondary aims included assessing the association of student-reported exposure to smoking in vehicles and lifetime asthma diagnosis and future intentions to smoke. METHODS: Population-weighted data from the California Student Tobacco Survey and the National Youth Tobacco Survey were used to evaluate California and national trends, respectively. Weighted logistic regression models using California Student Tobacco Survey 2011 data assessed the association between the number of days of exposure to smoking in cars and student-reported lifetime asthma diagnosis as well as intention to smoke in the future. RESULTS: The proportion of California students reporting exposure to smoking in cars in the last 7 days declined <1% annually from 2001 through 2005, but declined 12% annually from 2007 to 2011. National trends did not show comparable declines after 2006. Students reporting exposure to smoking in vehicles were more likely to report having ever been diagnosed with asthma and intending to smoke in the future than students who were not exposed to SHS. CONCLUSIONS: These findings support the legislative intent that public policies that are designed to protect children from exposure to smoking in vehicles will yield better adolescent health outcomes and a lower risk of future adolescent cigarette smoking. [ABSTRACT FROM AUTHOR]

BACKGROUND: Little is known about the influence of environmental factors on the etiology of childhood brain tumors. OBJECTIVES: We examined risks for brain tumors in children after prenatal and infant exposure to monitored ambient air toxics. METHODS: We ascertained all cases of medulloblastoma, central nervous system primitive neuroectodermal tumor (PNET), and astrocytoma before 6 years of age diagnosed in 1990-2007 from the California Cancer Registry and selected controls randomly from birth rolls matched by birth year. Exposures to air toxics during pregnancy/infancy for 43 PNET, 34 medulloblastoma, and 106 astrocytoma cases and 30,569 controls living within 5 mi of a monitor were determined. With factor analysis we assessed the correlational structures of 26 probable carcinogenic toxics, and estimated odds ratios by brain tumor type in logistic regression models. RESULTS: PNETs (≤ 38 cases) were positively associated with interquartile range (IQR) increases in prenatal exposure to acetaldehyde [odds ratio (OR) = 2.30; 95% CI: 1.44, 3.67], 1,3-butadiene (OR = 2.23; 95% CI: 1.28, 3.88), benzene, and toluene; and with IQR increases in exposure during the first year of life to ortho-dichlorobenzene (OR = 3.27; 95% CI: 1.17, 9.14), 1,3-butadiene (OR = 3.15; 95% CI: 1.57, 6.32), and benzene. All exposures except ortho-dichlorobenzene loaded on the same factor. Medulloblastoma (≤ 30 cases) was associated with prenatal exposure to polycyclic aromatic hydrocarbons (PAHs combined: OR = 1.44; 95% CI: 1.15, 1.80). Exposures to lead and some PAHs during the first year of life were positively associated with astrocytoma, but the confidence intervals included the null value (e.g., for lead, OR = 1.40; 95% CI: 0.97, 2.03). CONCLUSIONS: Our data suggest that in utero and infancy exposures to air toxics generated by industrial and road traffic sources may increase the risk of PNET and medulloblastoma, with limited support for increased risks for astrocytoma in children up to age 6. [ABSTRACT FROM AUTHOR]

Occupational exposure to solvents, including n-hexane, has been associated with acquired color vision defects. Blue-yellow defects are most common and may be due to neurotoxicity or retinal damage. Acetone may potentiate the neurotoxicity of n-hexane. We present results on nonhexane solvent and hexane exposure and color vision from a cross-sectional study of 835 automotive repair workers in the San Francisco Bay Area, California (2007-2013). Cumulative exposure was estimated from self-reported work history, and color vision was assessed using the Lanthony desaturated D-15 panel test. Log-binomial regression was used to estimate prevalence ratios for color vision defects. Acquired color vision defects were present in 29% of participants, of which 70% were blue-yellow. Elevated prevalence ratios were found for nonhexane solvent exposure, with a maximum of 1.31 (95% confidence interval (CI): 0.86,2.00) for blue-yellow. Among participants aged <50 years, the prevalence ratio for blue-yellow defects was 2.17 (95% CI: 1.03, 4.56) in the highest quartile of nonhexane solvent exposure and 1.62 (95% CI: 0.97, 2.72) in the highest category of exposure to hexane with acetone coexposure. Cumulative exposures to hexane and nonhexane solvents in the highest exposure categories were associated with elevated prevalence ratios for color vision defects in younger participants. [ABSTRACT FROM AUTHOR]

BACKGROUND: Several studies have estimated the burden of coronary heart disease (CHD) mortality from ambient regional particulate matter ≤ 2.5 µm (PM2.5). The burden of near-roadway air pollution (NRAP) generally has not been examined, despite evidence of a causal link with CHD. OBJECTIVE: We investigated the CHD burden from NRAP and compared it with the PM2.5 burden in the California South Coast Air Basin for 2008 and under a compact urban growth greenhouse gas reduction scenario for 2035. METHODS: We estimated the population attributable fraction and number of CHD events attributable to residential traffic density, proximity to a major road, elemental carbon (EC), and PM2.5 compared with the expected disease burden if the population were exposed to background levels of air pollution. RESULTS: In 2008, an estimated 1,300 CHD deaths (6.8% of the total) were attributable to traffic density, 430 deaths (2.4%) to residential proximity to a major road, and 690 (3.7%) to EC. There were 1,900 deaths (10.4%) attributable to PM2.5. Although reduced exposures in 2035 should result in smaller fractions of CHD attributable to traffic density, EC, and PM2.5, the numbers of estimated deaths attributable to each of these exposures are anticipated to increase to 2,500, 900, and 2,900, respectively, due to population aging. A similar pattern of increasing NRAP-attributable CHD hospitalizations was estimated to occur between 2008 and 2035. CONCLUSION: These results suggest that a large burden of preventable CHD mortality is attributable to NRAP and is likely to increase even with decreasing exposure by 2035 due to vulnerability of an aging population. Greenhouse gas reduction strategies developed to mitigate climate change offer unexploited opportunities for air pollution health co-benefits. [ABSTRACT FROM AUTHOR]

The current study tested fine discrimination of upright and inverted faces and objects in adolescents with Autism Spectrum Disorder (ASD) as compared to age- and IQ-matched controls. Discrimination sensitivity was tested using morphed faces and morphed objects, and all stimuli were equated in low-level visual characteristics (luminance, contrast, spatial frequency make-up). Participants with ASD exhibited slight, non-significant impairments in discrimination sensitivity for faces, yet significantly enhanced discrimination sensitivity for objects. The ASD group also showed a protracted development of face and object inversion effects. Finally, for ASD participants, face sensitivity improved with increasing IQ while object sensitivity improved with age. By contrast, for controls, face sensitivity improved with age, but neither face nor object sensitivity was influenced by IQ. These findings suggest that individuals with ASD follow a qualitatively different path in the development of face and object processing abilities. [ABSTRACT FROM AUTHOR]

This article examines the theory and practice of "accelerated vehicle retirement," or "scrappage," programs during the 1990s and 2000s. Scrappage programs, championed by smokestack-industry executives, as well as local, state, and federal authorities, sought to purge the streets of older cars so that their supporters could meet their federal- and state-level air-quality-improvement targets on the cheap. Put another way, these programs aimed to reduce the overall emissions of the nation's fleet of cars--and, thus, to reduce overall air pollution--by hastening the pace of motor-vehicle obsolescence. Ultimately, vigorous opposition to these programs, especially though not exclusively among antique-and classic-car enthusiasts, led to their abandonment in all but a handful of cases. By examining both the origin and evolution of scrappage programs and the emergence of organized opposition to them, the article contemplates the relationship between the old and the new in the twentieth-century United States. [ABSTRACT FROM AUTHOR]

Objectives The objectives of this study were: (1) to characterise the exposure of non-smokers exposed to secondhand smoke (SHS) in a vehicle using biomarkers, (2) to describe the time course of the biomarkers over 24 h, and (3) to examine the relationship between tobacco biomarkers and airborne concentrations of SHS markers. Methods Eight non-smokers were individually exposed to SHS in cars with fully open front windows and closed back windows over an hour from a smoker who smoked three cigarettes at 20 min intervals. The non-smokers sat in the back seat on the passenger side, while the smoker sat in the driver's seat. Plasma cotinine and urine cotinine, 3-hydroxycotinine (3HC) and 4- (methylnitrosoamino)-(3-pyridyl)-1-butanol (NNAL) were compared in samples taken at baseline (BL) and several time-points after exposure. Nicotine, particulate matter (PM2.5) and carbon monoxide (CO) were measured inside and outside the vehicle and ventilation rates in the cars were measured. Results Average plasma cotinine and the molar sum of urine cotinine and 3HC (COT+3HC) increased four-fold, urine cotinine increased six-fold and urine NNAL increased ~27 times compared to BL biomarker levels. Plasma cotinine, urine COT+3HC and NNAL peaked at 4-8 h post-exposure while urine cotinine peaked within 4 h. Plasma cotinine was significantly correlated to PM2.5 (Spearman correlation rs=0.94) and CO (rs=0.76) but not to air nicotine. The correlations between urine biomarkers, cotinine, COT+3HC and NNAL, and air nicotine, PM2.5 and CO were moderate but nonsignificant (rs range = 0.31-0.60). Conclusions Brief SHS exposure in cars resulted in substantial increases in levels of tobacco biomarkers in non-smokers. For optimal characterisation of SHS exposure, tobacco biomarkers should be measured within 4-8 h post-exposure. Additional studies are needed to better describe the relationship between tobacco biomarkers and environmental markers of SHS. [ABSTRACT FROM AUTHOR]

Exposure to air pollution during pregnancy has been linked to the risk of childhood cancer, but the evidence remains inconclusive. In the present study, we used land use regression modeling to estimate prenatal exposures to traffic exhaust and evaluate the associations with cancer risk in very young children. Participants in the Air Pollution and Childhood Cancers Study who were 5 years of age or younger and diagnosed with cancer between 1988 and 2008 were had their records linked to California birth certificates, and controls were selected from birth certificates. Land use regression–based estimates of exposures to nitric oxide, nitrogen dioxide, and nitrogen oxides were assigned based on birthplace residence and temporally adjusted using routine monitoring station data to evaluate air pollution exposures during specific pregnancy periods. Logistic regression models were adjusted for maternal age, race/ethnicity, educational level, parity, insurance type, and Census-based socioeconomic status, as well as child's sex and birth year. The odds of acute lymphoblastic leukemia increased by 9%, 23%, and 8% for each 25-ppb increase in average nitric oxide, nitrogen dioxide, and nitrogen oxide levels, respectively, over the entire pregnancy. Second- and third-trimester exposures increased the odds of bilateral retinoblastoma. No associations were found for annual average exposures without temporal components or for any other cancer type. These results lend support to a link between prenatal exposure to traffic exhaust and the risk of acute lymphoblastic leukemia and bilateral retinoblastoma. [ABSTRACT FROM PUBLISHER]

Introduction Some car rental companies in California and other states in the USA have established non-smoking policies for their vehicles. This study examined the effectiveness of these policies in maintaining smoke-free rental cars. Methods A stratified random sample of 250 cars (non-smoker, smoker and unknown designation) was examined in San Diego County, California, USA. Dust, surfaces and the air of each vehicle cabin were sampled and analysed for residual tobacco smoke pollutants (also known as thirdhand smoke (THS)), and each car was inspected for visual and olfactory signs of tobacco use. Customer service representatives were informally interviewed about smoking policies. Findings A majority of putative non-smoker cars had nicotine in dust, on surfaces, in air and other signs of tobacco use. Independent of a car's smoking status, older and higher mileage cars had higher levels of THS pollution in dust and on surfaces (p<0.05), indicating that pollutants accumulated over time. Compared with smoker cars, non-smoker cars had lower levels of nicotine on surfaces (p<0.01) and in dust (p<0.05) and lower levels of nicotine (p<0.05) and 3-ethynylpyridine (p<0.05) in the air. Non-smoking signage in cars was associated with lower levels of THS pollutants in dust and air (p<0.05). Conclusions Existing policies and practices were successful in lowering THS pollution levels in non-smoker cars compared with smoker cars. However, policies failed in providing smoke-free rental cars; THS levels were not as low as those found in private cars of non-smokers with in-car smoking bans. Major obstacles include inconsistent communication with customers and the lack of routine monitoring and enforcement strategies. Strengthening policies and their implementation would allow car rental companies to reduce costs, better serve their customers and make a constructive contribution to tobacco control efforts. [ABSTRACT FROM AUTHOR]

Background: The emerging consensus that exposure to near-roadway traffic-related pollution causes asthma has implications for compact urban development policies designed to reduce driving and greenhouse gases. Objectives: We estimated the current burden of childhood asthma-related disease attributable to near-roadway and regional air pollution in Los Angeles County (LAC) and the potential health impact of regional pollution reduction associated with changes in population along major traffic corridors. Methods: The burden of asthma attributable to the dual effects of near-roadway and regional air pollution was estimated, using nitrogen dioxide and ozone as markers of urban combustion-related and secondary oxidant pollution, respectively. We also estimated the impact of alternative scenarios that assumed a 20% reduction in regional pollution in combination with a 3.6% reduction or 3.6% increase in the proportion of the total population living near major roads, a proxy for near-roadway exposure. Results: We estimated that 27,100 cases of childhood asthma (8% of total) in LAC were at least partly attributable to pollution associated with residential location within 75 m of a major road. As a result, a substantial proportion of asthma-related morbidity is a consequence of near-roadway pollution, even if symptoms are triggered by other factors. Benefits resulting from a 20% regional pollution reduction varied markedly depending on the associated change in near-roadway proximity. Conclusions: Our findings suggest that there are large and previously unappreciated public health consequences of air pollution in LAC and probably in other metropolitan areas with dense traffic corridors. To maximize health benefits, compact urban development strategies should be coupled with policies to reduce near-roadway pollution exposure. [ABSTRACT FROM AUTHOR]

Traffic-related air pollution is recognized as an important contributor to health problems. Epidemiologic analyses suggest that prenatal exposure to traffic-related air pollutants may be associated with adverse birth outcomes; however, there is insufficient evidence to conclude that the relation is causal. The Study of Air Pollution, Genetics and Early Life Events comprises all births to women living in 4 counties in California's San Joaquin Valley during the years 2000–2006. The probability of low birth weight among full-term infants in the population was estimated using machine learning and targeted maximum likelihood estimation for each quartile of traffic exposure during pregnancy. If everyone lived near high-volume freeways (approximated as the fourth quartile of traffic density), the estimated probability of term low birth weight would be 2.27% (95% confidence interval: 2.16, 2.38) as compared with 2.02% (95% confidence interval: 1.90, 2.12) if everyone lived near smaller local roads (first quartile of traffic density). Assessment of potentially causal associations, in the absence of arbitrary model assumptions applied to the data, should result in relatively unbiased estimates. The current results support findings from previous studies that prenatal exposure to traffic-related air pollution may adversely affect birth weight among full-term infants. [ABSTRACT FROM PUBLISHER]

Despite efforts to combat increasing rates of childhood obesity, the problem is worsening. Safe Routes to School (SRTS), an international movement motivated by the childhood obesity epidemic, seeks to increase the number of children actively commuting (walking or biking) to school by funding projects that remove barriers preventing them from doing so. We summarize the evaluation of the first phase of an ongoing SRTS program in California and discuss ways to enhance data collection. [ABSTRACT FROM AUTHOR]

Background: Numerous studies have linked criteria air pollutants with adverse birth outcomes, but there is less information on the importance of specific emission sources, such as traffic, and air toxics. Objectives: We used three exposure data sources to examine odds of term low birth weight (LBW) in Los Angeles, California, women when exposed to high levels of traffic-related air pollutants during pregnancy. Methods: We identified term births during 1 June 2004 to 30 March 2006 to women residing within 5 miles of a South Coast Air Quality Management District (SCAQMD) Multiple Air Toxics Exposure Study (MATES III) monitoring station. Pregnancy period average exposures were estimated for air toxics, including polycyclic aromatic hydrocarbons (PAHs), source-specific particulate matter < 2.5 µm in aerodynamic diameter (PM2.5) based on a chemical mass balance model, criteria air pollutants from government monitoring data, and land use regression (LUR) model estimates of nitric oxide (NO), nitrogen dioxide (NO2) and nitrogen oxides (NOx). Associations between these metrics and odds of term LBW (< 2,500 g) were examined using logistic regression. Results: Odds of term LBW increased approximately 5% per interquartile range increase in entire pregnancy exposures to several correlated traffic pollutants: LUR measures of NO, NO2, and NOx, elemental carbon, and PM2.5 from diesel and gasoline combustion and paved road dust (geological PM2.5). Conclusions: These analyses provide additional evidence of the potential impact of traffic-related air pollution on fetal growth. Particles from traffic sources should be a focus of future studies. INSET: CORRECTION. [ABSTRACT FROM AUTHOR]

Abstract: Intersection level of service (LOS) is a traffic engineering concept which measures how streets handle automobile traffic. It is widely used in transportation planning as an indicator of delay at intersections. The use of LOS is often criticized for its bias towards automobiles at the expense of bicycling, transit, and walking, and it complicates smart growth or compact development. In San Francisco, California, there is a political movement to eliminate the use of LOS in planning. But this movement has met significant obstacles and debate. In this paper I explore how the debate in San Francisco is unfolding and suggest implications for broader efforts to reconfigure urban streets and urban space in the United States and globally. [Copyright &y& Elsevier]

Abstract: Using a rich panel of data on welfare recipients in Alameda, Los Angeles, and San Joaquin Counties in California, this paper examined the relationship between transportation, human capital, family obstacles, socioeconomic constraints, and employment outcomes for welfare recipients. This paper reports the multinomial logit results that test the spatial mismatch hypothesis, car ownership thesis, and human capital thesis for employment outcome for welfare recipients. First, with respect to the spatial mismatch hypothesis, our work suggests that spatial proximity to jobs was not particularly important in explaining employment outcomes. Second, the private mobility measures, especially car ownership, were found to be significant predictors of employment and exiting welfare. Finally, human capital played an important role for welfare mothers who obtained a job and left the welfare system, and the number of children and their physical and mental challenges were significant barriers to economic self-sufficiency. [ABSTRACT FROM AUTHOR]

Three methods for collecting or generating fallout brake pad wear debris for environmental analysis were assessed: collection from wheels or hubs of automobiles (natural), generation from an inexpensive sanding process (sanded), and collection of fallout debris from dynamometer tests using the Los Angeles City Traffic protocol (LACT). Brake wear debris was collected from four automobiles with semimetalic brake pads and analyzed for physicochemical properties. For automobiles where all three types of debris were collected, bulk copper mass fractions ranged from 22-23% in sanded particles and 24-27% in LACTparticles, but were reduced to 1-6% in natural debris. The smaller copper mass fraction in natural debris was attributed to contamination with road dust, which was found to comprise 37-97% of the natural particles. The ratio of surface to bulk copper mass fraction was up to five times larger for natural than LACT debris, suggesting that copper may leach into stormwater faster and to a greater extent for natural particles. While the LACT method appears best for collecting only fallout particles, significant differences in copper distributions in the natural and LACT debris suggests that metal distribution in LACT debris may not be representative of fallout particles generated under actual driving conditions, where airborne road dust may play a role. Although dynamometer tests have been the preferred method for generating debris for assessment of metal dissolution from brake particles, data from this study indicate that such samples may result in biased estimates of metal leaching. [ABSTRACT FROM AUTHOR]

Since the 1920s, multiple historically specific factors led to the automobile-saturated environment of Los Angeles, contributing to a car-dependent lifestyle for most of its inhabitants. With car travel as its primary mode of mobility, and as a hub of numerous cultural industries throughout the twentieth century, the city has been the breeding ground for a number of car cultures, including hot rods, custom cars, and lowriders in addition to the large output of films and music recordings produced. In rap music of the early 1990s, producer/rapper Dr. Dre's (Andre Romelle Young) creation of a style labelled 'G-funk', according to him, was created and mixed specifically for listening in car stereo systems. This article provides one case study of music's intersections with geography, both the influence of urban geography on music production and the geography of particular listening spaces. As borrowing is central to hip-hop's ethos, Dr. Dre's production reflects how musical materials become re-used for a new space, updated and customized for the automotive listening experience. [ABSTRACT FROM AUTHOR]

As a typical car-dependent city, Los Angeles (LA) is extensively used as an example in research to illustrate car influences on city form. Focusing on the features of LA's geologic conditions and civil circumstances, we argued that the relationship between LA's low-density pattern and car dependence is more involved than previously deemed simple causality. The low density should be primarily credited to the spacious requirement of the mining industry, frequent earthquakes and multiethnic population of the city. Oil reserves in LA fueled its economic boom and fast urbanization that coincided with the start of mass production of cheap cars, and cars became medium-priced consumables for average families. Politicians preference for short construction-period projects enabled fast establishment of LA's highway infrastructure. The popularity of car use in return faciliatated further development of the low-density pattern of the city. The low-density urban form and car dependence created environmental and social problems for LA. Looking at P. R. China's motorization and urban development, we found that the trajectory of Beijing's motorization between 1978 and 2003 coincides with that of the U.S. in the 1910s and 1920s. Lessons from LA's urban and transportation development should be suggestive to China's urban and transportation planning. [ABSTRACT FROM AUTHOR]

The disparity of accessibility between cars and public transit provides important information about the degree of auto orientation in urban spatial structure. Using spatial data from 1990 and 2000 and a geographical information system, the present study examined the degrees and spatial variations of accessibility disparity between commuting by car and public transit as well as the temporal changes in this disparity in the metropolitan areas of Boston and San Francisco. In both metropolitan areas there was a considerable disparity in job accessibility in a comparison between users of cars and public transit, which turned out to differ substantially by location. Between 1990 and 2000 regional levels of this accessibility disparity lessened in the two metropolitan areas, but the temporal changes in the accessibility disparity varied considerably among different locations within the metropolitan areas. The accessibility disparity decreased in the majority of central areas and in a number of suburban zones near rail stations, whereas the accessibility disparity increased in a number of suburban zones near major highways. Improving accessibility for public transit, relative to that for cars, should be a key strategy for redressing auto-orientation urban spatial structure, an important objective of sustainable development. [ABSTRACT FROM AUTHOR]

An analysis of the California hydrogen fuelling network for passenger cars has been released by The California Air Resources Board. It reveals that, with the right funding, the network could be self-sufficient by 2030. The report, 'Hydrogen Station Network Self Sufficiency Analysis' finds that "Hydrogen fuelling network self-sufficiency can likely be achieved within the decade with additional State support beyond AB 8." [ABSTRACT FROM AUTHOR]

In auto-oriented communities, access to an automobile is essential for good mobility, but not everyone owns a car or is able to drive. Little is known about how individuals in these circumstances might still use vehicles for transportation. To provide insight on the nature of vehicle use by those with potentially limited vehicle access, we present qualitative findings from focus groups with recent Mexican immigrants living in California, half of whom owned no cars. Our results demonstrate varying degrees of participants’ access to vehicle travel not always corresponding to auto ownership, with extensive sharing of cars, borrowing of cars, and getting rides. We describe the different dimensions of vehicle access that participants experienced and identify specific factors that seemed to influence their access levels. We discuss the implications of our findings for transportation policy and future research. [ABSTRACT FROM AUTHOR]

Objective: The present study developed and tested a model of car following by human drivers.Background: Previous models of car following are based on 3-D parameters such as lead vehicle speed and distance information, which are not directly available to a driver. In the present paper we present the driving by visual angle (DVA) model, which is based on the visual information (visual angle and rate of change of visual angle) available to the driver.Method: Two experiments in a driving simulator examined car-following performance in response to speed variations of a lead vehicle defined by a sum of sine wave oscillations and ramp acceleration functions. In addition, the model was applied to six driving events using real world-driving data.Results: The model provided a good fit to car-following performance in the driving simulation studies as well as in real-world driving performance. A comparison with the advanced interactive microscopic simulator for urban and nonurban networks (AIMSUN) model, which is based on 3-D parameters, suggests that the DVA was more predictive of driver behavior in matching lead vehicle speed and distance headway.Conclusion: Car-following behavior can be modeled using only visual information to the driver and can produce performance more predictive of driver performance than models based on 3-D (speed or distance) information.Application: The DVA model has applications to several traffic safety issues, including automated driving systems and traffic flow models. [ABSTRACT FROM AUTHOR]

This research assessed in-vehicle exposures to black carbon (BC) as an indicator of diesel particulate matter (DPM) exposures. Approximately 50 h of real-time Aethalometer BC measurements were made inside vehicles driven on freeway and arterial loops in Los Angeles and Sacramento. Video tapes of the driver''s view were transcribed to record the traffic conditions, vehicles followed, and vehicle occupant observations, and these results were tested for their associations with BC concentration. In-vehicle BC concentrations were highest when directly following diesel-powered vehicles, particularly those with low exhaust pipe locations. The lowest BC concentrations were observed while following gasoline-powered passenger cars, on average no different than not following any vehicle. Because diesel vehicles were over-sampled in the field study, results were not representative of real-world driving. To calculate representative exposures, in-vehicle BC concentrations were grouped by the type of vehicle followed, for each road type and congestion level. These groupings were then re-sampled stochastically, in proportion to the fraction of statewide vehicle miles traveled (VMT) under each of those conditions. The approximately 6% of time spent following diesel vehicles led to 23% of the in-vehicle BC exposure, while the remaining exposure was due to elevated roadway BC concentrations. In-vehicle BC exposures averaged 6 μg m-3 in Los Angeles and the Bay Area, the regions with the highest congestion and the majority of the state''s VMT. The statewide average in-vehicle BC exposure was 4 μg m-3, corresponding to DPM concentrations of 7–23 μg m-3, depending on the Aethalometer response to elemental carbon (EC) and the EC fraction of the DPM. In-vehicle contributions to overall DPM exposures ranged from approximately 30% to 55% of total DPM exposure on a statewide population basis. Thus, although time spent in vehicles was only 1.5 h day-1 on average, vehicles may be the most important microenvironment for overall DPM exposure. [Copyright &y& Elsevier]

Investigates the size-segregated aerosol emissions from on-road vehicles in the Caldecott Tunnel in the San Francisco Bay Area, California. Determination of particle chemical compositions; Use of microorifice cascade impactors and filter-based samplers; Estimation of size distribution and chemical particulates.

Provides information pertaining to the rates of particulate emission relating to the high-emitting vehicles recruited in Orange County, California. Identification of one hundred three in-use vehicles; Details on the particulate matter composition; Ranging of fleet; Concerns of the atmospheric particulate.