Urban policy interventions to reduce traffic-related emissions and air pollution: A systematic evidence map.

BACKGROUND: Urban areas are hot spots for human exposure to air pollution, which originates in large part from traffic. As the urban population continues to grow, a greater number of people risk exposure to traffic-related air pollution (TRAP) and its adverse, costly health effects. In many cities, there is a need and scope for air quality improvements through targeted policy interventions, which continue to grow including rapidly changing technologies. OBJECTIVE: This systematic evidence map (SEM) examines and characterizes peer-reviewed evidence on urban-level policy interventions aimed at reducing traffic emissions and/or TRAP from on-road mobile sources, thus potentially reducing human exposures and adverse health effects and producing various co-benefits. METHODS: This SEM follows a previously peer-reviewed and published protocol with minor deviations, explicitly outlined here. Articles indexed in Public Affairs Index, TRID, Medline and Embase were searched, limited to English, published between January 1, 2000, and June 1, 2020. Covidence was used to screen articles based on previously developed eligibility criteria. Data for included articles was extracted and manually documented into an Excel database. Data visualizations were created in Tableau. RESULTS: We identified 7528 unique articles from database searches and included 376 unique articles in the final SEM. There were 58 unique policy interventions, and a total of 1,139 unique policy scenarios, comprising these interventions and different combinations thereof. The policy interventions fell under 6 overarching policy categories: 1) pricing, 2) land use, 3) infrastructure, 4) behavioral, 5) technology, and 6) management, standards, and services, with the latter being the most studied. For geographic location, 463 policy scenarios were studied in Europe, followed by 355 in Asia, 206 in North America, 57 in South America, 10 in Africa, and 7 in Australia. Alternative fuel technology was the most frequently studied intervention (271 times), followed by vehicle emission regulation (134 times). The least frequently studied interventions were vehicle ownership taxes, and studded tire regulations, studied once each. A mere 3 % of studies addressed all elements of the full-chain-traffic emissions, TRAP, exposures, and health. The evidence recorded for each unique policy scenario is hosted in an open-access, query-able Excel database, and a complementary interactive visualization tool. We showcase how users can find more about the effectiveness of the 1,139 included policy scenarios in reducing, increasing, having mixed or no effect on traffic emissions and/or TRAP. CONCLUSION: This is the first peer-reviewed SEM to compile international evidence on urban-level policy interventions to reduce traffic emissions and/or TRAP in the context of human exposure and health effects. We also documented reported enablers, barriers, and co-benefits. The open-access Excel database and interactive visualization tool can be valuable resources for practitioners, policymakers, and researchers. Future updates to this work are recommended. PROTOCOL REGISTRATION: Sanchez, K.A., Foster, M., Nieuwenhuijsen, M.J., May, A.D., Ramani, T., Zietsman, J. and Khreis, H., 2020. Urban policy interventions to reduce traffic emissions and traffic-related air pollution: Protocol for a systematic evidence map. Environment international, 142, p.105826.

Maternal exposure to polycyclic aromatic hydrocarbons in South Texas, evaluation of silicone wristbands as personal passive samplers.

BACKGROUND: Prenatal exposure to polycyclic aromatic hydrocarbons (PAHs) is associated with adverse health effects in children. Valid exposure assessment methods with accurate spatial and temporal resolution across pregnancy is a critical need for advancing environmental health studies. OBJECTIVE: The objective of this study was to quantify maternal PAH exposure in pregnant women residing in McAllen, Texas where the prematurity rate and childhood asthma prevalence rates are high. A secondary objective was to compare PAH levels in silicone wristbands deployed as passive samplers with concentrations measured using standardized active air-sampling techniques. METHODS: Participants carried a backpack that contained air-sampling equipment (i.e., filter and XAD sorbent) and a silicone wristband (i.e., passive sampler) for three nonconsecutive 24-h periods. Filters, XAD tubes, and wristbands were analyzed for PAHs. RESULTS: The median level of exposure for the sum of 16 PAHs measured via active sampling over 24 h was 5.54 ng/m3 (filters) and 43.82 ng/m3 (XADs). The median level measured in wristbands (WB) was 586.82 ng/band. Concentrations of the PAH compounds varied across sampling matrix type. Phenanthrene and fluorene were consistently measured for all participants and in all matrix types. Eight additional volatile PAHs were measured in XADs and WBs; the median level of exposure for the sum of these eight PAHs was 342.98 ng/m3 (XADs) and 632.27 ng/band. The silicone wristbands (WB) and XAD sorbents bound 1-methynaphthalyne, 2-methylnaphthalene, biphenyl following similar patterns of detection. SIGNIFICANCE: Since prior studies indicate linkages between PAH exposure and adverse health outcomes in children at the PAH levels detected in our study, further investigation on the associated health effects is needed. Data reflect the ability of silicone wristbands to bind smaller molecular weight, semivolatile PAHs similar to XAD resin. Application of wristbands as passive samplers may be useful in studies evaluating semivolatile PAHs.

Pilot study and cumulative risk framework to advance long-haul driver health.

Commercial drivers are essential to the economic recovery, yet their work exposes them to many health and safety hazards. Research to improve driver health should be designed with an understanding of both the complex occupational environment and the risk management context. We present results from a small pilot study of driver health concerns and behaviors to illustrate concepts and frameworks from human health risk assessment and management that may assist in the design and translation of driver and other worker health research. The pilot study surveyed 18 long-haul truck drivers at a truck stop using an instrument adapted from the International Physical Activity Questionnaire and a transient community needs assessment developed for the US Antarctic Program Recreation and Wellness Survey. Respondents' characteristics and health concerns reflect existing literature: mostly male of older age with musculoskeletal and chronic health conditions. The two most common barriers to physical activity were lack of time and physical limitations. Applying cumulative risk assessment and risk-based decision-making frameworks, we suggest that preventive health management opportunities can be improved for these transient workers through actions of employers, truck stop owners and their communities. Considering lessons learned in implementing the pilot, cumulative risk assessment, and risk-based decision making in research design can facilitate holistic research considering co-exposures, risk factors and mitigators across multiple domains of health to inform worker protection.

Near-Road Traffic-Related Air Pollution: Resuspended PM2.5 from Highways and Arterials.

Recent studies suggest that the transportation sector is a major contributor to fine particulate matter (PM2.5) in urban areas. A growing body of literature indicates PM2.5 exposure can lead to adverse health effects, and that PM2.5 concentrations are often elevated close to roadways. The transportation sector produces PM2.5 emissions from combustion, brake wear, tire wear, and resuspended dust. Traffic-related resuspended dust is particulate matter, previously deposited on the surface of roadways that becomes resuspended into the air by the movement of traffic. The objective of this study was to use regulatory guidelines to model the contribution of resuspended dust to near-road traffic-related PM2.5 concentrations. The U.S. Environmental Protection Agency (EPA) guidelines for quantitative hotspot analysis were used to predict traffic-related PM2.5 concentrations for a small network in Dallas, Texas. Results show that the inclusion of resuspended dust in the emission and dispersion modeling chain increases prediction of near-road PM2.5 concentrations by up to 74%. The results also suggest elevated PM2.5 concentrations near arterial roads. Our results are discussed in the context of human exposure to traffic-related air pollution.

Assessment of Traffic-Related Air Pollution: Case Study of Pregnant Women in South Texas.

Population groups vulnerable to adverse effects of traffic-related air pollution correspond to children, pregnant women and elderly. Despite these effects, literature is limited in terms of studies focusing on these groups and a reason often cited is the limited information on their mobility important for exposure assessment. The current study presents a method for assessing individual-level exposure to traffic-related air pollution by integrating mobility patterns tracked by global positioning system (GPS) devices with dynamics of air pollutant concentrations. The study is based on a pool of 17 pregnant women residing in Hidalgo County, Texas. The traffic-related particulate matter with diameter of less than 2.5 micrometer (PM2.5) emissions and air pollutant concentrations are predicted using MOVES and AERMOD models, respectively. The daily average traffic-related PM2.5 concentration was found to be 0.32 µg/m3, with the highest concentration observed in transit (0.56 µg/m3), followed by indoors (0.29 µg/m3), and outdoor (0.26 µg/m3) microenvironment. The obtained exposure levels exhibited considerable variation between time periods, with higher levels during peak commuting periods, close to the US-Mexico border region and lower levels observed during midday periods. The study also assessed if there is any difference between traffic-related dynamic exposure, based on time-varying mobility patterns, and static exposure, based solely on residential locations, and found a difference of 9%, which could be attributed to the participants' activity patterns being focused mostly indoors.

Traffic related air pollution and the burden of childhood asthma in the contiguous United States in 2000 and 2010.

BACKGROUND: Asthma is one of the leading chronic airway diseases among children in the United States (US). Emerging evidence indicates that Traffic Related Air Pollution (TRAP), as opposed to ambient air pollution, leads to the onset of childhood asthma. We estimated the number of incident asthma cases among children attributable to TRAP in the contiguous US, for the years 2000 and 2010. METHODS: The number of incident childhood asthma cases and percentage due to TRAP were estimated using standard burden of disease assessment methods. We combined children (<18 years) counts and pollutant exposures at populated US census blocks with a national asthma incidence rate and meta-analysis derived concentration response functions (CRF). NO2, PM2.5 and PM10 were used as surrogates of TRAP exposures, with NO2 being most specific. Annual average concentrations were obtained from previously validated land-use regression (LUR) models. Asthma incidence rate and a CRF for each pollutant were obtained from the literature. Estimates were stratified by urban or rural living and by median household income. We also estimated the number of preventable cases among blocks that exceeded the limit for two counterfactual scenarios. The first scenario used the recommended air quality annual averages from the World Health Organization (WHO) as a limit. The second scenario used the minimum modeled concentration for each pollutant, in either year, as a limit. RESULTS: Average concentrations in 2000 and 2010, respectively, were 20.6 and 13.2 µg/m3 for NO2, 12.1 and 9 µg/m3 for PM2.5 and 21.5 and 17.9 µg/m3 for PM10. Attributable number of cases ranged between 209,100-331,200 for the year 2000 and 141,900-286,500 for 2010, depending on the pollutant. Asthma incident cases due to TRAP represented 27%-42% of all cases in 2000 and 18%-36% in 2010. Percentage of cases due to TRAP were higher (1) in urban areas than rural areas, and (2) in block groups with lowest median household income. Online open-access interactive maps and tables summarizing findings at the county level and 498 major US cities, are available at [https://carteehdata.org/l/s/TRAP-burden-of-childhood-asthma]. Assuming that pollutants did not exceed WHO air quality recommendations, the number of incident cases that could have been prevented ranged between 300 and 53,400, depending on the pollutant and year. Assuming that pollutant levels were limited to the minimum modeled concentration, the number of childhood asthma incident cases that could have been prevented ranged between 127,700 and 317,600, depending on the pollutant and year. CONCLUSION: This is the first study to estimate the burden of incident childhood asthma attributable to TRAP at a national scale in the US. The attributable burden of childhood asthma dropped by 33% between 2000 and 2010. However, a significant proportion of cases can be prevented.

Maternal exposure to PM2.5 in south Texas, a pilot study.

In this study, we characterized personal exposure to fine particulate matter (PM2.5), black carbon (BC), and nicotine in pregnant women in Hidalgo County, where the hospitalization rates of childhood asthma are the highest in the state of Texas. The measurements were conducted over three non-consecutive sampling days for 17 participants in their third trimester. Measurements were partitioned into four microenvironments, i.e., Residential, Vehicular, Commercial, and Other, on the basis of GPS coordinates and temperature and humidity measurements. The daily average PM2.5 mass concentration was 24.2 (standard deviation=22.0) µg/m3, with the highest daily mass concentration reaching 126.0µg/m3. The daily average BC concentration was 1.44 (SD=0.82) µg/m3, ranging from 0.5 to 5.4µg/m3. Hair nicotine concentrations were all near the detection level (i.e., 49.2pg/mg), indicating that the participants were not routinely exposed to tobacco smoke. The Residential microenvironment contributed dominantly to the mass concentration since the participants chiefly remained at home and cooking activities contributed significantly to the total PM2.5. When compared to an ambient monitoring station, the person-specific PM2.5 was frequently more than double the ambient measurement (10.4µg/m3 overall), revealing that even in regions where ambient concentrations are below national standards, individuals may be still be exposed to elevated PM2.5 mass concentrations.

Specific model for the estimation of methane emission from municipal solid waste landfills in India.

The landfill gas (LFG) model is a tool for measuring methane (CH4) generation rates and total CH4 emissions from a particular landfill. These models also have various applications including the sizing of the LFG collection system, evaluating the benefits of gas recovery projects, and measuring and controlling gaseous emissions. This research paper describes the development of a landfill model designed specifically for Indian climatic conditions and the landfill's waste characteristics. CH4, carbon dioxide (CO2), oxygen (O2) and temperature were considered as the prime factor for the development of this model. The developed model was validated for three landfill sites in India: Shillong, Kolkata, and Jaipur. The autocorrelation coefficient for the model was 0.915, while the R(2) value was 0.429.

On-road heavy-duty vehicle emissions monitoring system.

The introduction of particulate and oxides of nitrogen (NOx) after-treatment controls on heavy-duty vehicles has spurred the need for fleet emissions data to monitor their reliability and effectiveness. The University of Denver has developed a new method for rapidly measuring heavy-duty vehicles for gaseous and particulate fuel specific emissions. The method was recently used to collect 3088 measurements at a Port of Los Angeles location and a weigh station on I-5 in northern California. The weigh station NOx emissions for 2014 models are 73% lower than 2010 models (3.8 vs 13.9 gNOx/kg of fuel) and look to continue to decrease with newer models. The Port site has a heavy-duty fleet that has been entirely equipped with diesel particulate filters since 2010. Total particulate mass and black carbon measurements showed that only 3% of the Port vehicles measured exceed expected emission limits with mean gPM/kg of fuel emissions of 0.031 ± 0.007 and mean gBC/kg of fuel emissions of 0.020 ± 0.003. Mean particulate emissions were higher for the older weigh station fleet but 2011 and newer trucks gPM/kg of fuel emissions were nevertheless more than a factor of 30 lower than the means for pre-DPF (2007 and older) model years.

Optimal deployment of emissions reduction technologies for construction equipment.

The objective of this research was to develop a multiobjective optimization model to deploy emissions reduction technologies for nonroad construction equipment to reduce emissions in a cost-effective and optimal manner. Given a fleet of construction equipment emitting different pollutants in the nonattainment (NA) and near -nonattainment (NNA) counties of a state and a set of emissions reduction technologies available for installation on equipment to control pollution/emissions, the model assists in determining the mix of technologies to be deployed so that maximum emissions reduction and fuel savings are achieved within a given budget. Three technologies considered for emissions reduction were designated as X, Y, and Z to keep the model formulation general so that it can be applied for any other set of technologies. Two alternative methods of deploying these technologies on a fleet of equipment were investigated with the methods differing in the technology deployment preference in the NA and NNA counties. The model having a weighted objective function containing emissions reduction benefits and fuel-saving benefits was programmed with C++ and ILOG-CPLEX. For demonstration purposes, the model was applied for a selected construction equipment fleet owned by the Texas Department of Transportation, located in NA and NNA counties of Texas, assuming the three emissions reduction technologies X, Y, and Z to represent, respectively, hydrogen enrichment, selective catalytic reduction, and fuel additive technologies. Model solutions were obtained for varying budget amounts to test the sensitivity of emissions reductions and fuel-savings benefits with increasing the budget. Different mixes of technologies producing maximum oxides of nitrogen (NO(x)) reductions and total combined benefits (emissions reductions plus fuel savings) were indicated at different budget ranges. The initial steep portion of the plots for NO(x) reductions and total combined benefits against budgets for different combinations of emissions reduction technologies indicated a high benefit-cost ratio at lower budget amounts. The rate of NO(x) reductions and the increase of combined benefits decreased with increasing the budget, and with the budget exceeding certain limits neither further NO(x) reductions nor increased combined benefits were observed. Finally, the Pareto front obtained would enable the decision-maker to achieve a noninferior optimal combination of total NO(x) reductions and fuel-savings benefits for a given budget.

Feasibility of landfill gas as a liquefied natural gas fuel source for refuse trucks.

The purpose of this paper is to develop a methodology to evaluate the feasibility of using landfill gas (LFG) as a liquefied natural gas (LNG) fuel source for heavy-duty refuse trucks operating on landfills. Using LFG as a vehicle fuel can make the landfills more self-sustaining, reduce their dependence on fossil fuels, and reduce emissions and greenhouse gases. Acrion Technologies Inc. in association with Mack Trucks Inc. developed a technology to generate LNG from LFG using the CO2 WASH process. A successful application of this process was performed at the Eco Complex in Burlington County, PA. During this application two LNG refuse trucks were operated for 600 hr each using LNG produced from gases from the landfill. The methodology developed in this paper can evaluate the feasibility of three LFG options: doing nothing, electricity generation, and producing LNG to fuel refuse trucks. The methodology involved the modeling of several components: LFG generation, energy recovery processes, fleet operations, economic feasibility, and decision-making. The economic feasibility considers factors such as capital, maintenance, operational, and fuel costs, emissions and tax benefits, and the sale of products such as surplus LNG and food-grade carbon dioxide (CO2). Texas was used as a case study. The 96 landfills in Texas were prioritized and 17 landfills were identified that showed potential for converting LFG to LNG for use as a refuse truck fuel. The methodology was applied to a pilot landfill in El Paso, TX. The analysis showed that converting LFG to LNG to fuel refuse trucks proved to be the most feasible option and that the methodology can be applied for any landfill that considers this option.