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In the latter half of the 20th century, Los Angeles had, by many measures, higher levels of photochemical air pollutants than any other major city in the United States (Figure 1). To address this problem, the California Air Resources Board and its partners became leaders in quantifying the health effects of air pollutants and in aggressively implementing pollution-control strategies.

Published Mar 5, 2015

Douglas W. Dockery, Sc.D., and James H. Ware, P. D. (2014). Cleaner Air, Bigger Lungs. New England Journal of Medicine, 1–2. https://doi.org/10.1056/NEJMsa1201918.6.

BACKGROUND
Air-pollution levels have been trending downward progressively over the past several decades in southern California, as a result of the implementation of air quality–control policies. We assessed whether long-term reductions in pollution were associated with improvements in respiratory health among children.

METHODS
As part of the Children’s Health Study, we measured lung function annually in 2120 children from three separate cohorts corresponding to three separate calendar periods: 1994–1998, 1997–2001, and 2007–2011. Mean ages of the children within each cohort were 11 years at the beginning of the period and 15 years at the end. Linear-regression models were used to examine the relationship between declining pollution levels over time and lung-function development from 11 to 15 years of age, measured as the increases in forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) during that period (referred to as 4-year growth in FEV1 and FVC).

RESULTS
Over the 13 years spanned by the three cohorts, improvements in 4-year growth of both FEV1 and FVC were associated with declining levels of nitrogen dioxide (P<0.001 for FEV1 and FVC) and of particulate matter with an aerodynamic diameter of less than 2.5 μm (P= 0.008 for FEV1 and P<0.001 for FVC) and less than 10 μm (P<0.001 for FEV1 and FVC). These associations persisted after adjustment for several potential confounders. Significant improvements in lung-function development were observed in both boys and girls and in children with asthma and children without asthma. The proportions of children with clinically low FEV1 (defined as <80% of the predicted value) at 15 years of age declined significantly, from 7.9% to 6.3% to 3.6% across the three periods, as the air quality improved (P=0.001). CONCLUSIONS We found that long-term improvements in air quality were associated with statistically and clinically significant positive effects on lung-function growth in children. (Funded by the Health Effects Institute and others.)

Published Mar 5, 2015

Gauderman WJ, Urman R, Avol E, et al. Association of improved air quality with lung development in children. N Engl J Med. 2015;372(10):905-913. doi:10.1056/NEJMoa1414123

Air pollution is a suspected developmental neurotoxicant. Many schools are located in
close proximity to busy roads, and traffic air pollution peaks when children are at school. We
aimed to assess whether exposure of children in primary school to traffic-related air pollutants is associated with impaired cognitive development.

Published Mar 3, 2015

Sunyer, J., Esnaola, M., Alvarez-Pedrerol, M., Forns, J., Rivas, I., López-Vicente, M., Suades-González, E., Foraster, M., Garcia-Esteban, R., Basagaña, X., Viana, M., Cirach, M., Moreno, T., Alastuey, A., Sebastian-Galles, N., Nieuwenhuijsen, M., & Querol, X. (2015). Association between Traffic-Related Air Pollution in Schools and Cognitive Development in Primary School Children: A Prospective Cohort Study. https://doi.org/10.1371/journal.pmed.1001792

Here, we present an expert consensus document on behalf of the European Society of Cardiology that explores the mechanisms and relationships between ambient air pollution and cardiovascular disease. The purpose of this document is to highlight and raise awareness of the importance and wide-ranging impact of air pollution on cardiovascular disease. It will also provide guidance to society, patients, and healthcare professionals on the potential health impacts of air pollution, and make recommendations for future public health and research priorities to manage and mitigate this avoidable cause of death and disease.

Published Jan 27, 2015

Newby, D. E., Mannucci, P. M., Tell, G. S., Baccarelli, A. A., Brook, R. D., Donaldson, K., Forastiere, F., Franchini, M., Franco, O. H., Graham, I., Hoek, G., Hoffmann, B., Hoylaerts, M. F., Künzli, N., Mills, N., Pekkanen, J., Peters, A., Piepoli, M. F., Rajagopalan, S., & Storey, R. F. (2015). Expert position paper on air pollution and cardiovascular disease. European Heart Journal, 36(2), 83–93. https://doi.org/10.1093/eurheartj/ehu458

Rationale: Few studies have examined associations between longterm exposure to fine particulate matter (PM2.5) and lung function decline in adults. Objectives: To determine if exposure to traffic and PM2.5 is associated with longitudinal changes in lung function in a population-based cohort in the Northeastern United States, where pollution levels are relatively low. Methods: FEV1 and FVC were measured up to two times between 1995 and 2011 among 6,339 participants of the Framingham Offspring or Third Generation studies. We tested associations between residential proximity to a major roadway and PM2.5 exposure in 2001 (estimated by a land-use model using satellite measurements of aerosol optical thickness) and lung function. We examined differences in average lung function using mixed-effects models and differences in lung function decline using linear regression models. Current smokers were excluded. Models were adjusted for age, sex, height, weight, pack-years, socioeconomic status indicators, cohort, time, season, and weather. Measurements and Main Results: Living less than 100 m from a major roadway was associated with a 23.2 ml (95% confidence interval [CI], -44.4 to -1.9) lower FEV1 and a 5.0 ml/yr (95% CI, -9.0 to -0.9) faster decline in FEV1 compared with more than 400 m. Each 2 μg/m3 increase in average of PM2.5 was associated with a 13.5 ml (95% CI, -26.6 to -0.3) lower FEV1 and a 2.1 ml/yr (95% CI, -4.1 to -0.2) faster decline in FEV1 There were similar associations with FVC. Associations with FEV1/FVC ratio were weak or absent. Conclusions: Long-term exposure to traffic and PM2.5, at relatively low levels, was associated with lower FEV1 and FVC and an accelerated rate of lung function decline.

Published Jan 23, 2015

Rice, M. B., Ljungman, P. L., Wilker, E. H., Dorans, K. S., Gold, D. R., Schwartz, J., Koutrakis, P., Washko, G. R., O’Connor, G. T., & Mittleman, M. A. (2015). Long-term exposure to traffic emissions and fine particulate matter and lung function decline in the Framingham Heart Study. American Journal of Respiratory and Critical Care Medicine, 191(6), 656–664. https://doi.org/10.1164/rccm.201410-1875OC

Outdoor air pollution is one of the leading contributors to adverse respiratory health outcomes in urban areas around the world. Children are highly sensitive to the adverse effects of air pollution due to their rapidly growing lungs, incomplete immune and metabolic functions, patterns of ventilation and high levels of outdoor activity. The Children’s Health Study (CHS) is a continuing series of longitudinal studies that first began in 1993 and has focused on demonstrating the chronic impacts of air pollution on respiratory illnesses from early childhood through adolescence. A large body of evidence from the CHS has documented that exposures to both regional ambient air and traffic-related pollutants are associated with increased asthma prevalence, new-onset asthma, risk of bronchitis and wheezing, deficits of lung function growth, and airway inflammation. These associations may be modulated by key genes involved in oxidative-nitrosative stress pathways via gene-environment interactions. Despite successful efforts to reduce pollution over the past 40 years, air pollution at the current levels still brings many challenges to public health. To further ameliorate adverse health effects attributable to air pollution, many more toxic pollutants may require regulation and control of motor vehicle emissions and other combustion sources may need to be strengthened. Individual interventions based on personal susceptibility may be needed to protect children’s health while control measures are being implemented.

Published Jan 1, 2015

Chen Z, Salam MT, Eckel SP, Breton CV, Gilliland FD. Chronic effects of air pollution on respiratory health in Southern California children: findings from the Southern California Children's Health Study. J Thorac Dis. 2015;7(1):46-58. doi:10.3978/j.issn.2072-1439.2014.12.20

Widespread adoption of plug-in electric vehicles (PEVs) may substantially reduce emissions of greenhouse gases while improving regional air quality and increasing energy security. However, outcomes depend heavily on the electricity generation process, power plant locations, and vehicle use decisions. This paper provides a clear methodology for predicting PEV emissions impacts by anticipating battery-charging decisions and power plant energy sources across Texas. Life-cycle impacts of vehicle production and use and Texans' exposure to emissions are also computed and monetized. This study reveals to what extent PEVs are more environmentally friendly, for most pollutant species, than conventional passenger cars in Texas, after recognizing the emissions and energy impacts of battery provision and other manufacturing processes. Results indicate that PEVs on today's grid can reduce GHGs, NOx, PM10, and CO in urban areas, but generate significantly higher emissions of SO2 than existing light-duty vehicles. Use of coal for electricity production is a primary concern for PEV growth, but the energy security benefits of electrified vehicle-miles endure. As conventional vehicle emissions rates improve, it appears that power grids must follow suit (by improving emissions technologies and/or shifting toward cleaner generation sources) to compete on an emissions-monetized basis with conventional vehicles in many locations. Moreover, while PEV pollution impacts may shift to more remote (power plant) locations, dense urban populations remain most strongly affected by local power plant emissions in many Texas locations.

Published Jan 1, 2015

Nichols, B. G., Kockelman, K. M., & Reiter, M. (2015). Air quality impacts of electric vehicle adoption in Texas. Transportation Research Part D: Transport and Environment, 34, 208–218. https://doi.org/10.1016/j.trd.2014.10.016

I examine the effect of school indoor air quality (IAQ) on academic outcomes. I utilize a quasi-natural experiment, in which IAQ-renovations were completed at virtually every school in a single Texas school district at different points in time, combined with a panel of student-level data to control for many confounding factors and thereby uncover the causal effect of IAQ-renovations on academic outcomes. Results indicate that performance on standardized tests significantly improves while attendance is unresponsive to improvements in IAQ. Rough calculations suggest that IAQ-renovations may be a more cost-effective way to improve standardized test scores than class size reductions.

Published Nov 2, 2014

Stafford, T. M. (2015). Indoor air quality and academic performance. Journal of Environmental Economics and Management, 70, 34–50. https://doi.org/10.1016/j.jeem.2014.11.002

Cognitive performance is critical to productivity in many occupations and potentially linked to pollution exposure. We evaluate this potentially important relationship by estimating the effect of pollution exposure on standardized test scores among Israeli high school high-stakes tests (2000-2002). Since students take multiple exams on multiple days in the same location after each grade, we can adopt a fixed effects strategy estimating models with city, school, and student fixed effects. We focus on fine particulate matter (PM2.5) and carbon monoxide (CO), which are considered to be two of the most dangerous forms of air pollution. We find that while PM2.5 and CO levels are only weakly correlated with each other, both exhibit a robust negative relationship with test scores. We also find that PM2.5, which is thought to be particularly damaging for asthmatics, has a larger negative impact on groups with higher rates of asthma. For CO, which affects neurological functioning, the effect is more homogenous across demographic groups. Furthermore, we find that exposure to either pollutant is associated with a significant decline in the probability of not receiving a Bagrut certificate, which is required for college entrance in Israel. The results suggest that the gain from improving air quality may be underestimated by a narrow focus on health impacts. Insofar as air pollution may lead to reduced cognitive performance, the consequences of pollution may be relevant for a variety of everyday activities that require mental acuity. Moreover, by temporarily lowering the productivity of human capital, high pollution levels lead to allocative inefficiency as students with lower human capital are assigned a higher rank than their more qualified peers. This may lead to inefficient allocation of workers across occupations, and possibly a less productive workforce

Published Oct 1, 2014

Lavy, V., & Roth, S. (2014). The Impact of Short Term Exposure to Ambient Air Pollution on Cognitive Performance and Human Capital Formation. National Bureau of Economic Research, 1–40. https://doi.org/10.3386/w20648

Investigate whether air pollution affect academic performance of school children in California using fixed effect least squares regression and fixed effect quantile regression. This issue has not be studied previously by economists; the two studies in the epidemiological literature considering it would not be considered as measuring causal effects by economists. Quantile regression allows us to investigate how pollution affects different parts of the achievement distribution, and has not been used previously in this literature.

Published Apr 1, 2014

Avol, J. C. H. J. S. Z. ; E. (2014). Pollution, Test Scores and the Distribution Of Academic Achievement: Evidence From California Schools, 2002-2008. https://www.smu.edu.sg/sites/default/files/economics/shea2014/presentation/pollution_talk_april_2014_ham2.pdf