Kevin Lewis

January 06, 2021

Long Term Impact of Childhood Exposure to Pollution on Children’s Test Scores
Sajad Vahedi
Journal of Family and Economic Issues, December 2020, Pages 729–748


Recent studies examined relationships between childhood exposure to pollution and long-term outcomes, such as schooling. The literature, however, has yet to address the underlying mechanism of these relationships. In this study, I estimated a production function of skill formation for children aged 3 to 15 years old and simultaneously accounted for their exposure to pollution using a structural model. I used the Letter-Word (LW) test scores from the Panel Study of Income Dynamics as a measure of children’s skills and ozone as a measure of pollution. I found that a one standard deviation increase in ozone led to a 0.07 standard deviation reduction in the LW test scores on average. This negative effect varied with a child’s age: the LW test score of 3 year olds dropped by 0.10 standard deviation in response to one standard deviation increase in pollution levels, whereas for the 14 year olds this effect was about half as much, 0.04 standard deviation. I also found that households exhibited compensatory behavior and mitigated the negative effect of pollution by investing more in their children. I demonstrated that reduction of pollution levels or income transfers to families could remediate the negative impact of childhood exposure to pollution on adult outcomes.

Proximity, NIMBYism, and Public Support for Energy Infrastructure
David Konisky, Stephen Ansolabehere & Sanya Carley
Public Opinion Quarterly, forthcoming


The public opinion literature examining the role of proximity and not-in-my-backyard (NIMBY) attitudes in people’s judgments about energy projects has come to inconclusive findings. We argue that these mixed results are due to vast differences and significant limitations in research designs, which we mitigate through a large study (n = 16,200) of Americans’ attitudes toward energy projects. Our approach examines a diverse set of energy projects in development, explicitly compares the attitudes of individuals living in the vicinity of projects with those farther away, and includes the careful measurement of the NIMBY concept. The analyses show little evidence that proximity in general or NIMBY objections in particular are important determinants of project support. Instead, other factors are more important, including perceptions of local environmental quality, risk orientation, concern about climate change, and trust in energy companies.

The phantom chorus: Birdsong boosts human well-being in protected areas
Danielle Ferraro et al.
Proceedings of the Royal Society B: Biological Sciences, December 2020


Spending time in nature is known to benefit human health and well-being, but evidence is mixed as to whether biodiversity or perceptions of biodiversity contribute to these benefits. Perhaps more importantly, little is known about the sensory modalities by which humans perceive biodiversity and obtain benefits from their interactions with nature. Here, we used a ‘phantom birdsong chorus' consisting of hidden speakers to experimentally increase audible birdsong biodiversity during ‘on' and ‘off' (i.e. ambient conditions) blocks on two trails to study the role of audition in biodiversity perception and self-reported well-being among hikers. Hikers exposed to the phantom chorus reported higher levels of restorative effects compared to those that experienced ambient conditions on both trails; however, increased restorative effects were directly linked to the phantom chorus on one trail and indirectly linked to the phantom chorus on the other trail through perceptions of avian biodiversity. Our findings add to a growing body of evidence linking mental health to nature experiences and suggest that audition is an important modality by which natural environments confer restorative effects. Finally, our results suggest that maintaining or improving natural soundscapes within protected areas may be an important component to maximizing human experiences.

East Side Story: Historical Pollution and Persistent Neighborhood Sorting
Stephan Heblich, Alex Trew & Yanos Zylberberg
Journal of Political Economy, forthcoming


Why are the east sides of formerly industrial cities more deprived? To answer this question, we use individual-level census data and create historical pollution patterns derived from the locations of 5,000 industrial chimneys and an atmospheric model. We show that this observation results from path dependent neighborhood sorting that began during the Industrial Revolution as prevailing winds blew pollution eastwards. Past pollution explains up to 20% of the observed neighborhood segregation in 2011, even though coal pollution stopped in the 1970s. We develop a quantitative model to identify the role of neighborhood effects and relocation rigidities in underlying this persistence.

Lead Exposure Reduces Academic Performance: Intensity, Duration, and Nutrition Matter
Alex Hollingsworth et al.
NBER Working Paper, December 2020


We leverage a natural experiment, where a large national automotive racing organization switched from leaded to unleaded fuel, to study how ambient lead exposure and nutrition impact learning in elementary school. The average race emitted more than 10 kilograms of lead — a quantity similar to the annual emissions of an airport or a median lead-emitting industrial facility in the United States. Increased levels and duration of exposure to lead negatively affect academic performance, shift the entire academic performance distribution, and negatively impact both younger and older children. We provide quasi-experimental evidence linking measured quantities of lead emissions to decreased test scores, information essential for policies addressing ambient lead and emission sources. Exposure to 10 additional kilograms of lead emissions reduces standardized test scores by 0.07 standard deviations. This corresponds to an average income reduction of $9,000 per treated student in present value terms, an effect of similar magnitude as improving teacher value added by one standard deviation, reducing class size by 10 students, or increasing school spending per pupil by $2,500. The marginal impacts of lead are larger in impoverished, non-white counties, and among students with greater duration of exposure, even after controlling for total exposure. Factors correlated with better nutrition — most notably consumption of calcium-rich foods like milk — help mitigate the link between lead exposure and reduced educational outcomes. These results show that improved child nutrition can help combat the negative effects of lead, addressing several prominent social issues including racial test gaps, human capital formation across income groups, and disparities in regional environmental justice.

The Capital Market Impact of Blackrock’s Thermal Coal Divestment Announcement
Alexander Bassen, Thomas Kaspereit & Daniel Buchholz
Finance Research Letters, forthcoming


This study examines how coal companies were affected by the announcement of thermal coal divestment made by Blackrock, a large institutional asset manager. Following the announcement, the largest thermal coal mining companies exhibited negative abnormal returns. However, the stock prices of other firms were not affected. Blackrock’s own share price increased following the announcement. We provide additional evidence that Blackrock protected its clients by lowering its exposure towards affected companies before the announcement. Overall, our results show that divestment has significant impacts on the companies in question and that the capital market sees divestment as value-enhancing for the divesting institution.

Polluting Public Funds: The Effect of Environmental Regulation on Municipal Bonds
Akshaya Jha, Stephen Karolyi & Nicholas Muller
NBER Working Paper, December 2020


We present three findings on the effects of environmental regulation on the municipal bond market. First, yields increase (decrease) after a new standard is proposed (finalized), consistent with the resolution of regulatory uncertainty. Second, around annual compliance announcements, yields fall for counties that remain in compliance but increase for newly noncompliant counties. Third, yields are substantially higher for bonds from counties just above the pollution threshold relative to counties just below the threshold. Our findings suggest that increases in regulatory stringency or uncertainty over future environmental policy increase the cost of municipal debt raised to fund critical infrastructure.

PM2.5 associated with gray matter atrophy reflecting increased Alzheimers risk in older women
Diana Younan et al.
Neurology, forthcoming

Objective: To examine whether late-life exposure to PM2.5 (particulate matter with aerodynamic diameters <2.5-µm) contributes to progressive brain atrophy predictive of Alzheimer’s disease (AD) using a community-dwelling cohort of women (aged 70-89) with up to two brain MRI scans (MRI-1: 2005-6; MRI-2: 2010-11).

Methods: AD pattern similarity (AD-PS) scores, developed by supervised machine learning and validated with MRI data from the AD Neuroimaging Initiative, was used to capture high-dimensional gray matter atrophy in brain areas vulnerable to AD (e.g., amygdala, hippocampus, parahippocampal gyrus, thalamus, inferior temporal lobe areas and midbrain). Based on participants’ addresses and air monitoring data, we implemented a spatiotemporal model to estimate 3-year average exposure to PM2.5 preceding MRI-1. General linear models were used to examine the association between PM2.5 and AD-PS scores (baseline and 5-year standardized change), accounting for potential confounders and white matter lesion volumes.

Results: For 1365 women aged 77.9±3.7 years in 2005-6, there was no association between PM2.5 and baseline AD-PS score in cross-sectional analyses (β=-0.004; 95% CI: -0.019, 0.011). Longitudinally, each interquartile range increase of PM2.5 (2.82-µg/m3) was associated with increased AD-PS scores during the follow-up, equivalent to a 24% (hazard ratio=1.24; 95% CI: 1.14, 1.34) increase in AD risk over 5-years (n=712; aged 77.4±3.5 years). This association remained after adjustment for socio-demographics, intracranial volume, lifestyle, clinical characteristics, and white matter lesions, and was present with levels below US regulatory standards (<12-µg/m3).

Sources of particulate-matter air pollution and its oxidative potential in Europe
Kaspar Daellenbach et al.
Nature, 19 November 2020, Pages 414–419


Particulate matter is a component of ambient air pollution that has been linked to millions of annual premature deaths globally. Assessments of the chronic and acute effects of particulate matter on human health tend to be based on mass concentration, with particle size and composition also thought to play a part. Oxidative potential has been suggested to be one of the many possible drivers of the acute health effects of particulate matter, but the link remains uncertain. Studies investigating the particulate-matter components that manifest an oxidative activity have yielded conflicting results. In consequence, there is still much to be learned about the sources of particulate matter that may control the oxidative potential concentration. Here we use field observations and air-quality modelling to quantify the major primary and secondary sources of particulate matter and of oxidative potential in Europe. We find that secondary inorganic components, crustal material and secondary biogenic organic aerosols control the mass concentration of particulate matter. By contrast, oxidative potential concentration is associated mostly with anthropogenic sources, in particular with fine-mode secondary organic aerosols largely from residential biomass burning and coarse-mode metals from vehicular non-exhaust emissions. Our results suggest that mitigation strategies aimed at reducing the mass concentrations of particulate matter alone may not reduce the oxidative potential concentration. If the oxidative potential can be linked to major health impacts, it may be more effective to control specific sources of particulate matter rather than overall particulate mass.

Human-induced earthquakes, risk salience, and housing values
Wesley Burnett & Christopher Mothorpe
Resource and Energy Economics, forthcoming


Oklahoma’s households have recently faced several thousand higher-probability but low-impact earthquakes induced by nearby shale gas development. This type of seismic activity is different from natural-occurring earthquakes, which are generally constituted by one, high-loss event. We investigate the mechanisms through which earthquakes may influence household perceptions of risk by modeling changes to property values in and out of seismically-active zones. We estimate that the induced earthquakes are spatially concentrated, which is partially influenced by governmental limits placed on natural gas production and wastewater injections. Additionally, we explore the underlying measure of earthquake intensity and identify its importance in modeling seismic impacts. Controlling for the stock-flow dynamics of seismicity through time, we estimate that Oklahoma County’s cumulative experience of earthquakes led to a diminution of property values. The impacts are further exacerbated by risk-saliency effects, as reflected in declining values associated with nearby wastewater injections and natural gas production.

Conservation cobenefits from air pollution regulation: Evidence from birds
Yuanning Liang et al.
Proceedings of the National Academy of Sciences, 8 December 2020, Pages 30900-30906


Massive wildlife losses over the past 50 y have brought new urgency to identifying both the drivers of population decline and potential solutions. We provide large-scale evidence that air pollution, specifically ozone, is associated with declines in bird abundance in the United States. We show that an air pollution regulation limiting ozone precursors emissions has delivered substantial benefits to bird conservation. Our estimates imply that air quality improvements over the past 4 decades have stemmed the decline in bird populations, averting the loss of 1.5 billion birds, ∼20% of current totals. Our results highlight that in addition to protecting human health, air pollution regulations have previously unrecognized and unquantified conservation cobenefits.

Global human-made mass exceeds all living biomass
Emily Elhacham et al.
Nature, 17 December 2020, Pages 442–444


Humanity has become a dominant force in shaping the face of Earth. An emerging question is how the overall material output of human activities compares to the overall natural biomass. Here we quantify the human-made mass, referred to as ‘anthropogenic mass’, and compare it to the overall living biomass on Earth, which currently equals approximately 1.1 teratonnes. We find that Earth is exactly at the crossover point; in the year 2020 (± 6), the anthropogenic mass, which has recently doubled roughly every 20 years, will surpass all global living biomass. On average, for each person on the globe, anthropogenic mass equal to more than his or her bodyweight is produced every week. This quantification of the human enterprise gives a mass-based quantitative and symbolic characterization of the human-induced epoch of the Anthropocene.


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