Research Hub

The growth of worldwide environmental awareness has prompted numerous countries to focus on developing energy-conservation and carbon-reduction technology. The advancement of such technology enables the emergence of low-noise, low-polluting alternatives for bus systems, such as hybrid-electric, battery-electric, and fuel-cell electric buses (e-buses). For such buses to serve the existing schedules and lines operated by their conventional counterparts, reorganizing bus transportation systems is a major challenge and entails construction costs that comprise the costs of e-buses, battery capacity, chargers, and bus scheduling. To facilitate the development of environmentally friendly public transportation, this study proposes a model for simulating the operation and battery charging schedule of plug-in e-buses on the basis of an existing schedule and line network. The model was used to estimate the overall construction cost of converting the existent bus transportation system into an all plug-in e-bus one. Focusing on the bus transportation system in Penghu, an archipelago of Taiwan, this case study examined the effects of day- and nighttime charging requirements on the construction cost of an e-bus transportation system to improve the practicability of e-buses. It also applied a genetic algorithm to determine the minimum construction cost, which varied depending on the number of e-buses, level of battery capacity, number of chargers, and electricity costs. The optimized parameters involved the hourly residual battery capacity and battery charging times during the daytime operating hours. The results showed that although daytime charging involved electricity uses during peak hours and thus incurred additional costs, it contributed to the use of e-buses and an overall reduction in the construction cost. In summary, the proposed optimization method would successfully reduce the construction cost of the Penghu e-bus transportation system.

Published Sep 1, 2016

Ke, B. R., Chung, C. Y., & Chen, Y. C. (2016). Minimizing the costs of constructing an all plug-in electric bus transportation system: A case study in Penghu. Applied Energy, 177, 649–660. https://doi.org/10.1016/j.apenergy.2016.05.152

Background The contribution of modifiable risk factors to the increasing global and regional burden of stroke is unclear, but knowledge about this contribution is crucial for informing stroke prevention strategies. We used data from the Global Burden of Disease Study 2013 (GBD 2013) to estimate the population-attributable fraction (PAF) of stroke-related disability-adjusted life-years (DALYs) associated with potentially modifiable environmental, occupational, behavioural, physiological, and metabolic risk factors in different age and sex groups worldwide and in high-income countries and low-income and middle-income countries, from 1990 to 2013. Methods We used data on stroke-related DALYs, risk factors, and PAF from the GBD 2013 Study to estimate the burden of stroke by age and sex (with corresponding 95% uncertainty intervals [UI]) in 188 countries, as measured with stroke-related DALYs in 1990 and 2013. We evaluated attributable DALYs for 17 risk factors (air pollution and environmental, dietary, physical activity, tobacco smoke, and physiological) and six clusters of risk factors by use of three inputs: risk factor exposure, relative risks, and the theoretical minimum risk exposure level. For most risk factors, we synthesised data for exposure with a Bayesian meta-regression method (DisMod-MR) or spatial-temporal Gaussian process regression. We based relative risks on meta-regressions of published cohort and intervention studies. Attributable burden for clusters of risks and all risks combined took into account evidence on the mediation of some risks, such as high body-mass index (BMI), through other risks, such as high systolic blood pressure (SBP) and high total cholesterol. Findings Globally, 90·5% (95% UI 88·5–92·2) of the stroke burden (as measured in DALYs) was attributable to the modifiable risk factors analysed, including 74·2% (95% UI 70·7–76·7) due to behavioural factors (smoking, poor diet, and low physical activity). Clusters of metabolic factors (high SBP, high BMI, high fasting plasma glucose, high total cholesterol, and low glomerular filtration rate; 72·4%, 95% UI 70·2–73·5) and environmental factors (air pollution and lead exposure; 33·4%, 95% UI 32·4–34·3) were the second and third largest contributors to DALYs. Globally, 29·2% (95% UI 28·2–29·6) of the burden of stroke was attributed to air pollution. Although globally there were no significant differences between sexes in the proportion of stroke burden due to behavioural, environmental, and metabolic risk clusters, in the low-income and middle-income countries, the PAF of behavioural risk clusters in males was greater than in females. The PAF of all risk factors increased from 1990 to 2013 (except for second-hand smoking and household air pollution from solid fuels) and varied significantly between countries. Interpretation Our results suggest that more than 90% of the stroke burden is attributable to modifiable risk factors, and achieving control of behavioural and metabolic risk factors could avert more than three-quarters of the global stroke burden. Air pollution has emerged as a significant contributor to global stroke burden, especially in low-income and middle-income countries, and therefore reducing exposure to air pollution should be one of the main priorities to reduce stroke burden in these countries. Funding Bill & Melinda Gates Foundation, American Heart Association, US National Heart, Lung, and Blood Institute, Columbia University, Health Research Council of New Zealand, Brain Research New Zealand Centre of Research Excellence, and National Science Challenge, Ministry of Business, Innovation and Employment of New Zealand.

Published Jun 9, 2016

Feigin, V. L., Roth, G. A., Naghavi, M., Parmar, P., Krishnamurthi, R., Chugh, S., Mensah, G. A., Norrving, B., Shiue, I., Ng, M., Estep, K., Cercy, K., Murray, C. J. L., & Forouzanfar, M. H. (2016). Global burden of stroke and risk factors in 188 countries, during 1990–2013: a systematic analysis for the Global Burden of Disease Study 2013. The Lancet Neurology, 15(9), 913–924. https://doi.org/10.1016/S1474-4422(16)30073-4

Human civilization is currently facing two particular challenges: population growth with a strong trend towards urbanization and climate change. The latter is now no longer seriously questioned. The primary concern is to limit anthropogenic climate change and to adapt our societies to its effects. Schools are a key part of the structure of our societies. If future generations are to take control of the manifold global problems, we have to offer our children the best possible infrastructure for their education: not only in terms of the didactic concepts, but also with regard to the climatic conditions in the school environment. Between the ages of 6 and 19, children spend up to 8 h a day in classrooms. The conditions are, however, often inacceptable and regardless of the geographic situation, all the current studies report similar problems: classrooms being too small for the high number of school children, poor ventilation concepts, considerable outdoor air pollution and strong sources of indoor air pollution.There have been discussions about a beneficial and healthy air quality in classrooms for many years now and in recent years extensive studies have been carried out worldwide. The problems have been clearly outlined on a scientific level and there are prudent and feasible concepts to improve the situation. The growing number of publications also highlights the importance of this subject. High carbon dioxide concentrations in classrooms, which indicate poor ventilation conditions, and the increasing particle matter in urban outdoor air have, in particular, been identified as primary causes of poor indoor air quality in schools. Despite this, the conditions in most schools continue to be in need of improvement. There are many reasons for this. In some cases, the local administrative bodies do not have the budgets required to address such concerns, in other cases regulations and laws stand in contradiction to the demands for better indoor air quality, and sometimes the problems are simply ignored.This review summarizes the current results and knowledge gained from the scientific literature on air quality in classrooms. Possible scenarios for the future are discussed and guideline values proposed which can serve to help authorities, government organizations and commissions improve the situation on a global level.

Published May 8, 2016

Salthammer, T., Uhde, E., Schripp, T., Schieweck, A., Morawska, L., Mazaheri, M., Clifford, S., He, C., Buonanno, G., Querol, X., Viana, M., & Kumar, P. (2016). Children’s well-being at schools: Impact of climatic conditions and air pollution. Environment International, 94, 196–210. https://doi.org/10.1016/j.envint.2016.05.009

Importance: Childhood bronchitic symptoms are significant public and clinical health problems that produce a substantial burden of disease. Ambient air pollutants are important determinants of bronchitis occurrence.

Objective: To determine whether improvements in ambient air quality in Southern California were associated with reductions in bronchitic symptoms in children.

Design, Setting, and Participants: A longitudinal study involving 4602 children (age range, 5-18 years) from 3 cohorts was conducted during the 1993-2001, 1996-2004, and 2003-2012 years in 8 Southern California communities. A multilevel logistic model was used to estimate the association of changes in pollution levels with bronchitic symptoms.

Exposures: Average concentrations of nitrogen dioxide, ozone, particulate matter with an aerodynamic diameter of less than 10 µm (PM10) and less than 2.5 µm (PM2.5).

Main Outcomes and Measures: Annual age-specific prevalence of bronchitic symptoms during the previous 12 months based on the parent’s or child’s report of a daily cough for 3 months in a row, congestion or phlegm other than when accompanied by a cold, or bronchitis.

Results: The 3 cohorts included a total of 4602 children (mean age at baseline, 8.0 years; 2268 girls [49.3%]; 2081 Hispanic white [45.2%] ) who had data from 2 or more annual questionnaires. Among these children, 892 (19.4%) had asthma at age 10 years. For nitrogen dioxide, the odds ratio (OR) for bronchitic symptoms among children with asthma at age 10 years was 0.79 (95% CI, 0.67-0.94) for a median reduction of 4.9 ppb, with absolute decrease in prevalence of 10.1%. For ozone, the OR was 0.66 (95% CI, 0.50-0.86) for a median reduction of 3.6 ppb, with an absolute decrease in prevalence of 16.3%. For PM10, the OR was 0.61 (95% CI, 0.48-0.78) for a median reduction of 5.8 µg/m3, with an absolute decrease in prevalence of 18.7%. For PM2.5, the OR was 0.68 (95% CI, 0.53-0.86) for a median reduction of 6.8 µg/m3, with absolute decrease in prevalence of 15.4%. Among children without asthma (n = 3710), the ORs were 0.84 (95% CI, 0.76-0.92) for nitrogen dioxide; 0.85 (95% CI, 0.74-0.97) for ozone, 0.80 (95% CI, 0.70-0.92) for PM10, and 0.79 (95% CI, 0.69-0.91) for PM2.5; with absolute decrease in prevalence of 1.8% for nitrogen dioxide, 1.7% for ozone, 2.2% for PM10, and 2.3% for PM2.5. The associations were similar or slightly stronger at age 15 years.

Conclusions and Relevance: Decreases in ambient pollution levels were associated with statistically significant decreases in bronchitic symptoms in children. Although the study design does not establish causality, the findings support potential benefit of air pollution reduction on asthma control.

Published Apr 12, 2016

Berhane, K., Chang, C. C., McConnell, R., Gauderman, W. J., Avol, E., Rapapport, E., Urman, R., Lurmann, F., & Gilliland, F. (2016). Association of Changes in Air Quality With Bronchitic Symptoms in Children in California, 1993-2012. JAMA, 315(14), 1491–1501. https://doi.org/10.1001/JAMA.2016.3444

Epidemiologic studies can measure exposure to volatile organic compounds (VOCs) using environmental samples, biomarkers, questionnaires, or observations. These different exposure assessment approaches each have advantages and disadvantages; thus, evaluating relationships is an important consideration. In the National Children’s Vanguard Study from 2009 to 2010, participants completed questionnaires and data collectors observed VOC exposure sources and collected urine samples from 488 third trimester pregnant women at in-person study visits. From urine, we simultaneously quantified 28 VOC metabolites of exposure to acrolein, acrylamide, acrylonitrile, benzene, 1-bromopropane, 1,3-butadiene, carbon disulfide, crotonaldehyde, cyanide, N,N-dimethylformamide, ethylbenzene, ethylene oxide, propylene oxide, styrene, tetrachloroethylene, toluene, trichloroethylene, vinyl chloride, and xylene exposures using ultra high performance liquid chromatography coupled with an electrospray ionization tandem mass spectrometry (UPLC-ESI/MSMS) method. Urinary thiocyanate was measured using an ion chromatography coupled with an electrospray ionization tandem mass spectrometry method (IC-ESI/MSMS). We modeled the relationship between urinary VOC metabolite concentrations and sources of VOC exposure. Sources of exposure were assessed by participant report via questionnaire (use of air fresheners, aerosols, paint or varnish, organic solvents, and passive/active smoking) and by observations by a trained data collector (presence of scented products in homes). We found several significant (p < 0.01) relationships between the urinary metabolites of VOCs and sources of VOC exposure. Smoking was positively associated with metabolites of the tobacco constituents acrolein, acrylamide, acrylonitrile, 1,3-butadiene, crotonaldehyde, cyanide, ethylene oxide, N,N-dimethylformamide, propylene oxide, styrene, and xylene. Study location was negatively associated with the toluene metabolite N-acetyl-S-(benzyl)-L-cysteine (BMA), and paint use was positively associated with the xylene metabolites 2-methylhippuric acid (2MHA) and 3-Methylhippuric acid & 4-methylhippuric acid (3MHA + 4MHA). A near-significant (p = 0.06) relationship was observed between acrylamide metabolites and observation of incense.

Published Mar 29, 2016

Boyle, E. B., Viet, S. M., Wright, D. J., Merrill, L. S., Alwis, K. U., Blount, B. C., Mortensen, M. E., Moye, J., & Dellarco, M. (2016). Assessment of exposure to VOCs among pregnant women in the national children’s study. International Journal of Environmental Research and Public Health, 13(4). https://doi.org/10.3390/ijerph13040376

An integrated life cycle assessment and life cycle cost (LCC) model was developed to compare the life cycle performance of plug-in charging versus wireless charging for an electric bus system. The model was based on a bus system simulation using existing transit bus routes in the Ann Arbor–Ypsilanti metro area in Michigan. The objective is to evaluate the LCCs for an all-electric bus system utilizing either plug-in or wireless charging and also compare these costs to both conventional pure diesel and hybrid bus systems. Despite a higher initial infrastructure investment for off-board wireless chargers deployed across the service region, the wireless charging bus system has the lowest LCC of US$0.99 per bus-kilometer among the four systems and has the potential to reduce use-phase carbon emissions attributable to the lightweighting benefits of on-board battery downsizing compared to plug-in charging. Further uncertainty analysis and sensitivity analysis indicate that the unit price of battery pack and day or night electricity price are key parameters in differentiating the LCCs between plug-in and wireless charging. Additionally, scenario analyses on battery recycling, carbon emission pricing, and discount rates were conducted to further analyze and compare their respective life cycle performance.

Published Mar 24, 2016

Bi, Z., De Kleine, R., & Keoleian, G. A. (2017). Integrated Life Cycle Assessment and Life Cycle Cost Model for Comparing Plug-in versus Wireless Charging for an Electric Bus System. Journal of Industrial Ecology, 21(2), 344–355. https://doi.org/10.1111/jiec.12419

Mental acuity is essential to productivity in most professions and possibly associated with indoor air quality. I examine this potential link using a sample of university final examination results from a British institution. To account for potential confounders, I exploit the panel structure of the data to estimate models with subject and student fixed effects. I find that exposure to elevated levels of particulate matter (PM 10) has a statistically and economically significant effect on test scores and long-term academic indicators that are potentially correlated with future career outcomes. Furthermore, I find that the effect is larger among male, high ability and STEM subgroups and is present at levels considerably lower than current EPA standards. The results suggest that a narrow focus on traditional health outcomes, such as hospitalization, may understate the true cost of pollution as indoor air quality also affects productivity.

Published Mar 1, 2016

Roth, S. (2016). The Contemporaneous Effect of Indoor Air Pollution on Cognitive Performance: Evidence from the UK *. http://www.who.int/mediacentre/factsheets/fs292/en/.

Preterm birth (PTB) has been associated with exposure to air pollution, but it is unclear whether effects might vary among air pollution sources and components. Objectives: We studied the relationships between PTB and exposure to different components of air pollution, including gases and particulate matter (PM) by size fraction, chemical composition, and sources. Methods: Fine and ultrafine PM (respectively, PM2.5 and PM0.1) by source and composition were modeled across California over 2000–2008. Measured PM2.5, nitrogen dioxide, and ozone concentrations were spatially interpolated using empirical Bayesian kriging. Primary traffic emissions at fine scale were modeled using CALINE4 and traffic indices. Data on maternal characteristics, pregnancies, and birth outcomes were obtained from birth certificates. Associations between PTB (n = 442,314) and air pollution exposures defined according to the maternal residence at birth were examined using a nested matched case–control approach. Analyses were adjusted for maternal age, race/ethnicity, education and neighborhood income. Results: Adjusted odds ratios for PTB in association with interquartile range (IQR) increases in average exposure during pregnancy were 1.133 (95% CI: 1.118, 1.148) for total PM2.5, 1.096 (95% CI: 1.085, 1.108) for ozone, and 1.079 (95% CI: 1.065, 1.093) for nitrogen dioxide. For primary PM, the strongest associations per IQR by source were estimated for onroad gasoline (9–11% increase), followed by onroad diesel (6–8%) and commercial meat cooking (4–7%). For PM2.5 composition, the strongest positive associations per IQR were estimated for nitrate, ammonium, and secondary organic aerosols (11–14%), followed by elemental and organic carbon (2–4%). Associations with local traffic emissions were positive only when analyses were restricted to births with residences geocoded at the tax parcel level. Conclusions: In our statewide nested case–control study population, exposures to both primary and secondary pollutants were associated with an increase in PTB.

Published Feb 19, 2016

Laurent, Olivier, Hu, Jianlin , Li, Lianfa, Kleema, Michael J. , Bartell, Scott M., Cockburn, Myles, Escobedo, Loraine, and Wu, J. (2016). Research | Children ’ s Health A Statewide Nested Case – Control Study of Preterm Birth and Air Pollution. Environmental Health Perspectives, 124(9), 2001–2008. https://doi.org/10.1289/ehp.1002365

In 2010, the Louisiana Asthma Management and Prevention Program (LAMP) implemented the Asthma-Friendly Schools Initiative in high-risk Louisiana populations. The social ecological model (SEM) was used as a framework for an asthma program implemented in 70 state K-12 public schools over 2 years. METHODS: Activities included a needs assessment, identification of students with asthma, individualized asthma action plans (AAP), staff trainings, environmental quality improvement, and school system policy changes to address the asthma burden. RESULTS: There were 522 new or existing asthma cases recognized. Asthma knowledge/awareness was measurably improved among school personnel. School indoor air quality was improved across all locations. School-level polices were adopted that improved AAP collection, compliance to bus-idling restrictions, and asthma medication self-carry. CONCLUSIONS: The SEM framework can be used for school-based programs to address successfully and improve asthma-related issues from the individual through policy levels.

Published Feb 2, 2016

Nuss, H. J., Hester, L. L., Perry, M. A., Stewart-Briley, C., Reagon, V. M., & Collins, P. (2016). Applying the Social Ecological Model to Creating Asthma-Friendly Schools in Louisiana. Journal of School Health, 86(3), 225–232. https://doi.org/10.1111/josh.12369

Prior research demonstrates that mortality rates increase during economic booms and decrease during economic busts, but little is known about the role of environmental risks as a potential mechanism for this relationship. We investigate the contribution of air pollution to the procyclicality of deaths by combining county-level data on overall, cause-specific, and age-specific mortality rates with county-level measures of ambient concentrations of three types of pollutants and the unemployment rate. After controlling for demographic variables and state-by-year fixed effects, we find a significant positive correlation between pollution concentrations and mortality rates. Controlling for carbon monoxide, particulate matter, and ozone attenuates the relationship between overall mortality and the unemployment rate by 17%. The findings are robust to the use of state- rather than county-level data and to a variety of alternative specifications, although the attenuation of the unemployment-mortality relationship after controlling for pollution is insubstantial when including county-specific linear trends.

Published Feb 1, 2016

Heutel, G., & Ruhm, C. J. (2013). NBER WORKING PAPER SERIES AIR POLLUTION AND PROCYCLICAL MORTALITY. http://www.nber.org/papers/w18959