Kevin Lewis

March 18, 2020

Understanding How Low Levels of Early Lead Exposure Affect Children’s Life-Trajectories
Hans Grönqvist, Peter Nilsson & Per-Olof Robling
Journal of Political Economy, forthcoming


We study the impact of lead exposure from birth to adulthood and provide evidence on the mechanisms producing these effects. Following 800,000 children differentially exposed to the phaseout of leaded gasoline in Sweden, we find that even a low exposure affects long-run outcomes, that boys are more affected, and that changes in non-cognitive skills explain a sizeable share of the impact on crime and human capital. The effects are greater above exposure thresholds still relevant for the general population, and reductions in exposure equivalent to the magnitude of the recent redefinition of elevated blood-lead levels can increase earnings by 4%.

Loss of life expectancy from air pollution compared to other risk factors: A worldwide perspective
Jos Lelieveld et al.
Cardiovascular Research, forthcoming

Methods and results: We used a data-informed atmospheric model to calculate worldwide exposure to PM2.5 and ozone pollution, which was combined with the GEMM to estimate disease-specific excess mortality and loss of life expectancy (LLE) in 2015. Using this model, we investigated the effects of different pollution sources, distinguishing between natural (wildfires, aeolian dust) and anthropogenic emissions, including fossil fuel use. Global excess mortality from all ambient air pollution is estimated at 8.8 (7.11–10.41) million/year, with an LLE of 2.9 (2.3–3.5) years, being a factor of two higher than earlier estimates, and exceeding that of tobacco smoking. The global mean mortality rate of about 120 per 100 000 people/year is much exceeded in East Asia (196 per 100 000/year) and Europe (133 per 100 000/year). Without fossil fuel emissions, the global mean life expectancy would increase by 1.1 (0.9–1.2) years and 1.7 (1.4–2.0) years by removing all potentially controllable anthropogenic emissions. Because aeolian dust and wildfire emission control is impracticable, significant LLE is unavoidable.

Conclusion: Ambient air pollution is one of the main global health risks, causing significant excess mortality and LLE, especially through cardiovascular diseases. It causes an LLE that rivals that of tobacco smoking. The global mean LLE from air pollution strongly exceeds that by violence (all forms together), i.e. by an order of magnitude (LLE being 2.9 and 0.3 years, respectively).

Housing Discrimination and Pollution Exposures in the United States
Peter Christensen, Ignacio Sarmiento-Barbieri & Christopher Timmins
NBER Working Paper, February 2020


Local pollution exposures disproportionately impact minority households, but the root causes remain unclear. This study conducts a correspondence experiment on a major online housing platform to test whether housing discrimination constrains minority access to housing options in markets with significant sources of airborne chemical toxics. We find that renters with African American or Hispanic/LatinX names are 41% less likely than renters with White names to receive responses for properties in low exposure locations. We find no evidence of discriminatory constraints in high exposure locations, indicating that discrimination increases relative access to housing choices at elevated exposure risk.

Can Pollution Cause Poverty? The Effects of Pollution on Educational, Health and Economic Outcomes
Claudia Persico
American University Working Paper, February 2020


Although pollution is widespread, there is little evidence about how it might harm children’s long-run outcomes. Using the detailed, geocoded data that follows national representative cohorts of children born to the National Longitudinal Survey of Youth respondents over time, I compare siblings who were gestating before versus after a Toxic Release Inventory site opened or closed within one mile of their home. I find that children who were exposed prenatally to industrial pollution have lower wages, are more likely to be in poverty as adults, have fewer years of completed education, and are less likely to graduate high school.

The effect of air pollution on criminal activities: Evidence from the NOx Budget Trading Program
Siyu Chen & Teng Li
Regional Science and Urban Economics, forthcoming


This paper examines the impacts of air pollution on criminal activities by exploiting three dimensions of variations observed under a rich quasi-experiment: the NOx Budget Trading Program. This program has been well documented to decrease air pollution concentrations in participating states. Employing a triple-difference estimator, we find evidence showing that the program significantly reduced violent and property crimes in participating states by roughly 3.7% and 2.9%, respectively. Instrumental variable estimates suggest that lowering air pollution may play an important role in reducing criminal behaviors.

Premature mortality related to United States cross-state air pollution
Irene Dedoussi et al.
Nature, 13 February 2020, Pages 261–265


Outdoor air pollution adversely affects human health and is estimated to be responsible for five to ten per cent of the total annual premature mortality in the contiguous United States. Combustion emissions from a variety of sources, such as power generation or road traffic, make a large contribution to harmful air pollutants such as ozone and fine particulate matter (PM2.5). Efforts to mitigate air pollution have focused mainly on the relationship between local emission sources and local air quality. Air quality can also be affected by distant emission sources, however, including emissions from neighbouring federal states. This cross-state exchange of pollution poses additional regulatory challenges. Here we quantify the exchange of air pollution among the contiguous United States, and assess its impact on premature mortality that is linked to increased human exposure to PM2.5 and ozone from seven emission sectors for 2005 to 2018. On average, we find that 41 to 53 per cent of air-quality-related premature mortality resulting from a state’s emissions occurs outside that state. We also find variations in the cross-state contributions of different emission sectors and chemical species to premature mortality, and changes in these variations over time. Emissions from electric power generation have the greatest cross-state impacts as a fraction of their total impacts, whereas commercial/residential emissions have the smallest. However, reductions in emissions from electric power generation since 2005 have meant that, by 2018, cross-state premature mortality associated with the commercial/residential sector was twice that associated with power generation. In terms of the chemical species emitted, nitrogen oxides and sulfur dioxide emissions caused the most cross-state premature deaths in 2005, but by 2018 primary PM2.5 emissions led to cross-state premature deaths equal to three times those associated with sulfur dioxide emissions. These reported shifts in emission sectors and emission species that contribute to premature mortality may help to guide improvements to air quality in the contiguous United States.

Shale gas development has limited effects on stream biology and geochemistry in a gradient-based, multiparameter study in Pennsylvania
Adam Mumford et al.
Proceedings of the National Academy of Sciences, 18 February 2020, Pages 3670-3677


The number of horizontally drilled shale oil and gas wells in the United States has increased from nearly 28,000 in 2007 to nearly 127,000 in 2017, and research has suggested the potential for the development of shale resources to affect nearby stream ecosystems. However, the ability to generalize current studies is limited by the small geographic scope as well as limited breadth and integration of measured chemical and biological indicators parameters. This study tested the hypothesis that a quantifiable, significant relationship exists between the density of oil and gas (OG) development, increasing stream water concentrations of known geochemical tracers of OG extraction, and the composition of benthic macroinvertebrate and microbial communities. Twenty-five headwater streams that drain lands across a gradient of shale gas development intensity were sampled. Our strategy included comprehensive measurements across multiple seasons of sampling to account for temporal variability of geochemical parameters, including known shale OG geochemical tracers, and microbial and benthic macroinvertebrate communities. No significant relationships were found between the intensity of OG development, shale OG geochemical tracers, or benthic macroinvertebrate or microbial community composition, whereas significant seasonal differences in stream chemistry were observed. These results highlight the importance of considering spatial and temporal variability in stream chemistry and biota and not only the presence of anthropogenic activities in a watershed. This comprehensive, integrated study of geochemical and biological variability of headwater streams in watersheds undergoing OG development provides a robust framework for examining the effects of energy development at a regional scale.

Messaging for environmental action: The role of moral framing and message source
Kristin Hurst & Marc Stern
Journal of Environmental Psychology, forthcoming


Divisions between political Liberals and Conservatives on environmental issues seem to be widening, with Liberals generally more pro-environmental than Conservatives. We propose that common framing of environmental messages tends to perpetuate these gaps. We designed two experiments to examine this assumption and explore the prospects of narrowing these divisions using communication based on moral foundations theory. Moral foundations theory posits that there are at least five universal moral concerns that people intuitively use to form judgments. Research has found that political Liberals in the United States tend to base their judgments and communication on only two of these foundations, while Conservatives stress all five. We crafted two pro-environmental messages, one framed using liberal moral language (based on the two liberal moral foundations), the other using conservative moral language (based on all five moral foundations). Through survey research using two separate samples, we compared how political partisans responded to the messages when they were communicated from a liberal, conservative or nonpartisan message source. We found that the conservatively framed message resonated more with Conservatives than the liberally framed message, especially when combined with a conservative message source. Further, the conservatively framed message did not alienate liberal participants, even when combined with a conservative source. Thus, combining conservative framing (based on all five moral foundations) and conservative message sources in environmental messaging is likely to be more persuasive than relying on traditional liberal messaging or liberal sources.

Early atmospheric contamination on the top of the Himalayas since the onset of the European Industrial Revolution
Paolo Gabrielli et al.
Proceedings of the National Academy of Sciences, 25 February 2020, Pages 3967-3973


Because few ice core records from the Himalayas exist, understanding of the onset and timing of the human impact on the atmosphere of the “roof of the world” remains poorly constrained. We report a continuous 500-y trace metal ice core record from the Dasuopu glacier (7,200 m, central Himalayas), the highest drilling site on Earth. We show that an early contamination from toxic trace metals, particularly Cd, Cr, Mo, Ni, Sb, and Zn, emerged at high elevation in the Himalayas at the onset of the European Industrial Revolution (∼1780 AD). This was amplified by the intensification of the snow accumulation (+50% at Dasuopu) likely linked to the meridional displacement of the winter westerlies from 1810 until 1880 AD. During this period, the flux and crustal enrichment factors of the toxic trace metals were augmented by factors of 2 to 4 and 2 to 6, respectively. We suggest this contamination was the consequence of the long-range transport and wet deposition of fly ash from the combustion of coal (likely from Western Europe where it was almost entirely produced and used during the 19th century) with a possible contribution from the synchronous increase in biomass burning emissions from deforestation in the Northern Hemisphere. The snow accumulation decreased and dry winters were reestablished in Dasuopu after 1880 AD when lower than expected toxic metal levels were recorded. This indicates that contamination on the top of the Himalayas depended primarily on multidecadal changes in atmospheric circulation and secondarily on variations in emission sources during the last 200 y.

Invisible oil beyond the Deepwater Horizon satellite footprint
Igal Berenshtein et al.
Science Advances, February 2020


Major oil spills are catastrophic events that immensely affect the environment and society, yet determining their spatial extent is a highly complex task. During the Deepwater Horizon (DWH) blowout, ~149,000 km2 of the Gulf of Mexico (GoM) was covered by oil slicks and vast areas of the Gulf were closed for fishing. Yet, the satellite footprint does not necessarily capture the entire oil spill extent. Here, we use in situ observations and oil spill transport modeling to examine the full extent of the DWH spill, focusing on toxic-to-biota (i.e., marine organisms) oil concentration ranges. We demonstrate that large areas of the GoM were exposed to invisible and toxic oil that extended beyond the boundaries of the satellite footprint and the fishery closures. With a global increase in petroleum production–related activities, a careful assessment of oil spills’ full extent is necessary to maximize environmental and public safety.

Fraccidents: The Impact of Fracking on Road Traffic Deaths
Minhong Xu & Yilan Xu
Journal of Environmental Economics and Management, forthcoming


Hydraulic fracturing, a.k.a., fracking, requires intense truck trips to transport a large volume of water within a narrow time window, posing a safety threat to other road users. This paper examines how fracking-related trucking affects fatal crashes in North Dakota using the exogenous timing of fracking operations near a road segment. The results show that an additional post-fracking well within six miles of a road segment led to 8% more fatal crashes and 7.1% higher per-capita costs in accidents. Transport activities at wells’ other operational stages did not affect fatal crashes. These additional crashes emerged mainly from collisions involving trucks, resulting from a higher traffic volume rather than a higher crash rate and occurring during daytime rush hours rather than during the rest of the day. Alcohol-involved crash drivers increased most likely due to their vulnerability to heavier fracking-induced traffic rather than more alcohol-involved truck drivers near the fracking sites.

The elephant in the room: What can we learn from California regarding the use of sport hunting of pumas (Puma concolor) as a management tool?
John Laundré & Christopher Papouchis
PLoS ONE, February 2020


Puma (Puma concolor) management in the western United States is highly contentious, particularly with regard to the use of sport hunting as a management tool. Since the 1970s, puma in ten western states have been managed by state fish and game agencies through the use of a sport hunt. The rationale presented by wildlife managers is that sport hunting, in addition to providing recreational hunting opportunities, also reduces threats to human safety and livestock safety, and increases populations of the puma’s ungulate prey, namely deer (Odocoileus sp.) and elk (Cervus elepus). We evaluated these claims using the state of California as a control, which has prohibited sport hunting since 1972, and employing data obtained from state and federal agencies with authority and control over puma management. Specifically, we tested four hypotheses: 1) sport hunting will suppress puma populations, 2) sport hunting will reduce the number of problematic puma-human encounters; 3) sport hunting will reduce puma predation on domestic livestock, and 4) sport hunting will reduce the impact of puma predation on wild ungulate numbers, resulting in increased hunting opportunities for the sport hunt of ungulates. Our results indicated, respectively, that relative to the 10 states where puma are hunted, California had 1) similar puma densities, 2) the 3rd lowest per capita problematic puma-human encounters, 3) similar per capita loss of cattle (P = 0.13) and a significantly lower (t = 5.7, P < 0.001) per capita loss of sheep, and 4) similar average deer densities while changes in annual deer populations correlated with changes in other states (F = 95.4, P < 0.001, R2 = 0.68). In sum, our analysis of the records obtained from state and federal wildlife agencies found no evidence that sport hunting of pumas has produced the management outcomes sought by wildlife managers aside from providing a sport hunting opportunity. Consequently, and particularly because other research suggests that sport hunting actually exacerbate conflicts between pumas and humans, we recommend that state agencies re-assess the use of sport hunting as a management tool for pumas.

Air pollution exposure is associated with the gut microbiome as revealed by shotgun metagenomic sequencing
Farnaz Fouladi et al.
Environment International, forthcoming


Animal work indicates exposure to air pollutants may alter the composition of the gut microbiota. This study examined relationships between air pollutants and the gut microbiome in young adults residing in Southern California. Our results demonstrate significant associations between exposure to air pollutants and the composition of the gut microbiome using whole-genome sequencing. Higher exposure to 24-hour O3 was associated with lower Shannon diversity index, higher Bacteroides caecimuris, and multiple gene pathways, including L-ornithine de novo biosynthesis as well as pantothenate and coenzyme A biosynthesis I. Among other pollutants, higher NO2 exposure was associated with fewer taxa, including higher Firmicutes. The percent variation in gut bacterial composition that was explained by air pollution exposure was up to 11.2% for O3 concentrations, which is large compared to the effect size for many other covariates reported in healthy populations. This study provides the first evidence of significant associations between exposure to air pollutants and the compositional and functional profile of the human gut microbiome. These results identify O3 as an important pollutant that may alter the human gut microbiome.


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