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With growing agreement that credible pathways to zero carbon electricity exist, many support the notion that widespread electrification of the transportation sector will be an essential strategy for meeting scientifically-based midcentury climate goals. While transit buses have a relatively small impact on greenhouse gas emissions, they have a larger impact on urban air quality, have commercially available in-service electric models, and have historically commercialized clean technologies that enabled deployment in the rest of the heavy duty vehicle sector. This thesis seeks to understand what factors hinder or enable transit agencies to go beyond initial pilots to largely or wholly electrify their fleets, with the goal of understanding potential policies and strategies that could accelerate such a transition, without inhibiting existing or expanded transit service that also plays a key role in reducing carbon emissions, in order to improve local air pollution and support accelerated electrification of trucks and other heavy duty vehicles. Using public transit fleets in California, Kentucky, and Massachusetts as case studies, this thesis utilizes quantitative total cost of ownership and well-to-wheels greenhouse gas and air pollutant emissions analysis, and analysis of qualitative interviews with transit agency representatives to investigate the barriers, drivers, and potential solutions that could hinder or enable an accelerated yet sustainable transition to an electrified bus fleet. A total cost of ownership analysis reveals that electric buses may already be more cost effective than diesel buses in many case study utility service areas primarily due to fuel and maintenance cost savings, but are sensitive to key parameters such as annual mileage, electricity tariffs that vary widely by location, fossil fuel costs, policy context, and anticipated maintenance savings, and that cost savings from electric buses are likely to increase over time primarily due to anticipated reductions in battery costs and a faster increase in fossil fuel prices than electricity prices. While multiple agencies interviewed in California were planning to fully electrify their fleets, primarily due to political pressure and internal leadership, outside California where less supportive policies exist, fewer agencies were planning to procure additional electric buses, primarily due to high first cost and undesirable tradeoffs with maintaining or expanding transit service levels. Interview respondents reported other substantial barriers as well, such as oversubscribed discretionary grant programs, charging infrastructure costs, electricity costs, additional operational complexity, and performance uncertainty and risk, suggesting a need for multiple complementary policies to overcome these barriers and ensure agencies can transition to a new technology without impacting service. Important interventions identified include pursuing favorable electricity tariffs and electric charging infrastructure incentives through regulatory changes, and further leveraging limited public funds such as the Volkswagen settlement to develop low cost financing approaches similar to those utilized in the clean energy sector that can pledge anticipated operating savings to afford the incremental upfront cost. A set of complementary policies is then recommended to accelerate bus fleet electrification in each case study context, in order to achieve carbon reduction and air quality improvements for low income, urban communities without impacting transit service levels, and to help lead the way for the transition of other heavy duty fleets.

Published Jan 1, 2018

Blynn, K. (2018). Accelerating Bus Electrification: Enabling a sustainable transition to low carbon transportation systems. Massachusetts Institute of Technology. https://dspace.mit.edu/handle/1721.1/115600

Fossil-fuel combustion by-products are the world’s most significant threat to children’s health and future and are major contributors to global inequality and environmental injustice. The emissions include a myriad of toxic air pollutants and carbon dioxide (CO2), which is the most important human-produced climate-altering greenhouse gas. Synergies between air pollution and climate change can magnify the harm to children. Impacts include impairment of cognitive and behavioral development, respiratory illness, and other chronic diseases—all of which may be “seeded“ in utero and affect health and functioning immediately and over the life course. By impairing children’s health, ability to learn, and potential to contribute to society, pollution and climate change cause children to become less resilient and the communities they live in to become less equitable. The developing fetus and young child are disproportionately affected by these exposures because of their immature defense mechanisms and rapid development, especially those in low- and middle-income countries where poverty and lack of resources compound the effects. No country is spared, however: even high-income countries, especially low-income communities and communities of color within them, are experiencing impacts of fossil fuel-related pollution, climate change and resultant widening inequality and environmental injustice. Global pediatric health is at a tipping point, with catastrophic consequences in the absence of bold action. Fortunately, technologies and interventions are at hand to reduce and prevent pollution and climate change, with large economic benefits documented or predicted. All cultures and communities share a concern for the health and well-being of present and future children: this shared value provides a politically powerful lever for action. The purpose of this commentary is to briefly review the data on the health impacts of fossil-fuel pollution, highlighting the neurodevelopmental impacts, and to briefly describe available means to achieve a low-carbon economy, and some examples of interventions that have benefited health and the economy.

Published Dec 23, 2017

Perera, F. (2017). Pollution from Fossil-Fuel Combustion is the Leading Environmental Threat to Global Pediatric Health and Equity: Solutions Exist. International Journal of Environmental Research and Public Health 2018, Vol. 15, Page 16, 15(1), 16. https://doi.org/10.3390/IJERPH15010016

Read bios and background on this film covering the history of Old Smokey, the former incinerator, which operated from 1925 to 1970, and its environmental health impact on the West Grove community.

Published Nov 14, 2017

Law, U. of M. S. of. (2017). “Old Smokey: A Community History.” University of Miami School of Law. https://issuu.com/miamilaw/docs/ceps_oral_20history_20film_20projec

Electrification has been rapidly promoted to transform the energy source for public transit buses. Among all electric technologies penetrating the public bus fleet, battery electric buses (BEBs) dominates the market. Nevertheless, real-world energy consumption (EC) is of great concern, since BEBs are often used under congested conditions that may affect their energy and environmental benefits. This study proposes an operating mode binning method to assess on-road EC and well-to-wheel (WTW) air pollutants emissions of BEBs under complex real-world usage patterns. Second-by-second EC and operating data of two BEBs demonstrated in Macao, China is adopted to establish the EC profiles under each micro modes. Results show that EC value would be below zero in certain operation modes with negative vehicle specific power values, which suggests the regenerative brake system is effectively functioning under deceleration conditions. Average EC are estimated to be 1.7 to 4.1 kWh km−1 for BEB12 and 1.2 to 2.9 kWh km−1 for BEB10 (i.e., vehicle length of 12 m and 10 m), respectively, under all operating conditions (i.e., 18 various patterns) by average speed, loading mass and air conditioner usage. The large variation in real-world EC would proportionally affect WTW emissions of carbon dioxide (CO2) and air pollutants from BEBs. When deployed in Macao where non-fossil electricity is relatively abundant, BEB can significantly reduce WTW emissions of nitrogen oxides (NOX) and volatile organic compounds (VOC) by 60%–80%, along with considerable reductions of 10%–40% for CO2 and fine particulate matters (PM2.5). Further, the benefits related to WTW CO2 and PM2.5 emissions would not exist if BEBs are deployed in coal power-rich regions. Our measurement results and WTW emission suggests that current fuel economy testing procedure of BEB should be modified to better inform customers and policy-makers of their real-world performance and benefits.

Published Oct 17, 2017

He, X., Zhang, S., Ke, W., Zheng, Y., Zhou, B., Liang, X., & Wu, Y. (2018). Energy consumption and well-to-wheels air pollutant emissions of battery electric buses under complex operating conditions and implications on fleet electrification. Journal of Cleaner Production, 171, 714–722. https://doi.org/10.1016/j.jclepro.2017.10.017

A child's exposure to environmental pollutants can have life-long health effects. Thus it is critical to understand the potential exposure pathways. In this paper, we examine the increase in ambient PM2.5 concentrations at schools from private vehicle use for dropping children off at school. In North America, students are commonly driven to school in a private vehicle. Additionally, students walk or cycle, or take a school bus. Our vehicle surveys recorded between 23 and 116 personal vehicles at 25 schools, where enrolment ranged from 160 to 765 students. We fit a linear regression model to predict the number of vehicles at schools we did not observe within our study area, which explained 57% of the variation in our surveys. A microsimulation traffic model was created for each of the 86 schools we studied. Outputs from the traffic model were used to determine the emissions generated at each school. PM2.5 emissions varied from 0.14 to 6.38 g. Lastly, we dispersed the emissions produced by private vehicles dropping off students, which are emissions generated by unnecessary trips because students further than walking distance are provided transportation by the school board. At the drop-off location in front of the school, we found ambient concentration increases of at least 5 μg/m3, 10 μg/m3, 25 μg/m3 and 50 μg/m3 during 16.8%, 7.6%, 2.0% and 0.5% of the mornings, respectively. This research was conducted in a medium-sized North American city and should allow transferability to similar cities. We conclude that the use of private vehicles can significantly increase local concentrations, regardless of background conditions.

Published Sep 1, 2017

Adams, M. D., & Requia, W. J. (2017). How private vehicle use increases ambient air pollution concentrations at schools during the morning drop-off of children. Atmospheric Environment, 165, 264–273. https://doi.org/10.1016/j.atmosenv.2017.06.046

Although numerous studies have demonstrated links between particulate matter (PM) and adverse health effects, the chemical components of the PM mixture that cause injury are unknown. Objectives: This work characterizes spatial and temporal variability of PM2.5 (PM with aerodynamic diameter < 2.5 μm) components in the United States; our objective is to identify components for assessment in epidemiologic studies. Methods: We constructed a database of 52 PM2.5 component concentrations for 187 U.S. counties for 2000-2005. First, we describe the challenges inherent to analysis of a national PM2.5 chemical composition database. Second, we identify components that contribute substantially to and/or co-vary with PM2.5 total mass. Third, we characterize the seasonal and regional variability of targeted components. Results: Strong seasonal and geographic variations in PM2.5 chemical composition are identified. Only seven of the 52 components contributed ≥ 1% to total mass for yearly or seasonal averages [ammonium (NH4+), elemental carbon (EC), organic carbon matter (OCM), nitrate (NO3-), silicon, sodium (Na+), and sulfate (SO42-)]. Strongest correlations with PM2.5 total mass were with NH4+ (yearly), OCM (especially winter), NO3- (winter), and SO42- (yearly, spring, autumn, and summer), with particularly strong correlations for NH4+ and SO42- in summer. Components that co-varied with PM2.5 total mass, based on daily detrended data, were NH4+, SO42-, OCM, NO3-, bromine, and EC. Conclusions: The subset of identified PM2.5 components should be investigated further to determine whether their daily variation is associated with daily variation of health indicators, and whether their seasonal and regional patterns can explain the seasonal and regional heterogeneity in PM10 (PM with aerodynamic diameter < 10 μm) and PM2.5 health risks.

Published Jul 1, 2017

Bell, M. L., Dominici, F., Ebisu, K., Zeger, S. L., & Samet, J. M. (2007). Spatial and temporal variation in PM2.5 chemical composition in the United States for health effects studies. In Environmental Health Perspectives (Vol. 115, Issue 7, pp. 989–995). https://doi.org/10.1289/ehp.9621

Reports the results of a large study, including more than 60 million Medicare beneficiaries from the years 2000 through 2012, that addresses the association between annual average levels of PM2.5 and ozone,9 as measured at the ZIP Code level, and mortality. For every increase of 10 μg per cubic meter in PM2.5, there was an associated 7.3% increase in all-cause mortality (95% confidence interval [CI], 7.1 to 7.5), after adjustment for demographic characteristics, Medicaid eligibility, and area-level covariates. Below the current NAAQS for PM2.5 of 12 μg per cubic meter, the data showed that each increase in PM2.5 of 10 μg per cubic meter was associated with an even greater increase (13.6%) in mortality (95% CI, 13.1 to 14.1). There was no appreciable level below which the risk of death tapered off — and thus no “safe” level of PM2.5. Owing to the large size of the cohort, Di et al. were able to perform robust subgroup analyses and identified greater risks of death associated with air pollutants among blacks and Medicaid-eligible populations; moreover, these groups were more likely to be exposed to higher pollutant levels.

Published Jun 29, 2017

Berger, R. E., Ramaswami, R., Solomon, C. G., & Drazen, J. M. (2017). Air pollution still kills. New England Journal of Medicine, 376(26), 2591–2592. https://doi.org/10.1056/NEJMe1706865

Studies have shown that long-term exposure to air pollution increases mortality. However, evidence is limited for air-pollution levels below the most recent National Ambient Air Quality Standards. Previous studies involved predominantly urban populations and did not have the statistical power to estimate the health effects in underrepresented groups. METHODS We constructed an open cohort of all Medicare beneficiaries (60,925,443 persons) in the continental United States from the years 2000 through 2012, with 460,310,521 person-years of follow-up. Annual averages of fine particulate matter (particles with a mass median aerodynamic diameter of less than 2.5 μm [PM2.5]) and ozone were estimated according to the ZIP Code of residence for each enrollee with the use of previously validated prediction models. We estimated the risk of death associated with exposure to increases of 10 μg per cubic meter for PM2.5 and 10 parts per billion (ppb) for ozone using a two-pollutant Cox proportionalhazards model that controlled for demographic characteristics, Medicaid eligibility, and area-level covariates. RESULTS Increases of 10 μg per cubic meter in PM2.5 and of 10 ppb in ozone were associated with increases in all-cause mortality of 7.3% (95% confidence interval [CI], 7.1 to 7.5) and 1.1% (95% CI, 1.0 to 1.2), respectively. When the analysis was restricted to person-years with exposure to PM2.5 of less than 12 μg per cubic meter and ozone of less than 50 ppb, the same increases in PM2.5 and ozone were associated with increases in the risk of death of 13.6% (95% CI, 13.1 to 14.1) and 1.0% (95% CI, 0.9 to 1.1), respectively. For PM2.5, the risk of death among men, blacks, and people with Medicaid eligibility was higher than that in the rest of the population. CONCLUSIONS In the entire Medicare population, there was significant evidence of adverse effects related to exposure to PM2.5 and ozone at concentrations below current national standards. This effect was most pronounced among self-identified racial minorities and people with low income. (Supported by the Health Effects Institute and others.)

Published Jun 29, 2017

Di, Q., Wang, Y., Zanobetti, A., Wang, Y., Koutrakis, P., Choirat, C., Dominici, F., & Schwartz, J. D. (2017). Air pollution and mortality in the medicare population. New England Journal of Medicine, 376(26), 2513–2522. https://doi.org/10.1056/NEJMoa1702747

BACKGROUND: Daily changes in ambient concentrations of particulate matter, nitrogen oxides and ozone are associated with increased cardiopulmonary morbidity and mortality, with the lungs and their function being a vulnerable target. METHODS: To evaluate the association between daily changes in air pollution and lung function in healthy adults we obtained annual lung function measurements from a routine worker health surveillance program not designed for research purposes. Forced Vital Capacity (FVC), Forced Expiratory Volume in the first second (FEV1), FEV1/FVC and Peak Expiratory flow (PEF) from a cohort of 2449 employees were associated with daily measurements of PM10, NO2 and ozone at a nearby monitoring station in the North of Belgium. Repeated measures were available for the period 2011-2015. RESULTS: The mean (SD) PM10 concentration on the day of the lung function test was 24.9 (15.5) μg/m3. A 10 μg PM10/m3 increase on the day of the clinical examination was associated with a 18.9 ml lower FVC (95% CI: -27.5 to -10.3, p < 0.0001), 12.8 ml lower FEV1 (-19.1 to -6.5; p < 0.0001), and a 51.4 ml/s lower PEF (-75.0 to -27.0; p < 0.0001). The FEV1/FVC-ratio showed no associations. An increase of 10 μgNO2/m3 was associated with a reduction in PEF (-66.1 ml/s (-106.6 to -25.6; p < 0.001)) on the day of the examination. CONCLUSIONS: We found negative associations between daily variations in ambient air pollution and FVC, FEV1 and PEF in healthy adults.

Published Jun 14, 2017

Int Panis, L., Provost, E. B., Cox, B., Louwies, T., Laeremans, M., Standaert, A., Dons, E., Holmstock, L., Nawrot, T., & De Boever, P. (2017). Short-term air pollution exposure decreases lung function: a repeated measures study in healthy adults. Environmental Health : A Global Access Science Source, 16(1), 60. https://doi.org/10.1186/s12940-017-0271-z

How school location impacts children’s air pollution exposure and their ability to walk and bike to school has been a growing policy issue. Smart growth advocates encourage districts to locate schools in “walkable” locations, often near high-volume roadways while health professionals emphasize the importance of minimizing exposure to high levels of air pollution and distance schools from major roads. As states consider or implement laws to site schools away from high-volume roadways, such policies can lead to school locations disconnected from neighborhoods and accessible only by motorized transport modes. This study analyzes children’s air pollution exposure across an average school day, analyzing variation across roadway characteristics, local school and home environment, and mode choice for school commute. This research compares daily average exposures for children walking to a local school in a high-traffic area versus exposures if they were required to be bussed or driven to a distant, “greener” school located in a low-traffic environment. Daily average exposures to air pollution were estimated across an average school day (AM Commute, Unload, School Day, Load, PM Commute). The analysis also assesses how pollution exposure can be mitigated through clean school bus technology, improved HVAC systems, and no-idling policies. Bussing children from a high-traffic neighborhood to a distant school in a low-traffic environment resulted in average daily exposures from 2 to 4 times higher than children walking to their local school. The authors' simulated school siting policy assessment found that bussing children to a distant school in a “cleaner” air quality school site did not reduce average daily personal exposure of children who would otherwise walk or be driven/bussed to their local school in a “dirtier” air quality site. Mitigation measures like a clean bus fleet greatly reduce exposures for children bussing longer distances to a distant school while school HVAC improvements in a heavy-diesel/heavy-traffic school environment yield more conservative reductions.

Published Jun 1, 2017

Wolfe, M., McDonald, N., Arunachalam, S., & Valencia, A. (2017). Air Pollution Exposure during School Commutes. Journal of Transport & Health, 5, S48–S49. https://doi.org/10.1016/j.jth.2017.05.339