Air Pollution and Mortality in the Medicare Population
Qian Di et al.
New England Journal of Medicine, 29 June 2017, Pages 2513-2522
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 proportional-hazards 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.
Long-Run Pollution Exposure and Adult Mortality: Evidence from the Acid Rain Program
Alan Barreca, Matthew Neidell & Nicholas Sanders
NBER Working Paper, June 2017
Though over 90 percent of benefits from environmental quality improvements are attributed to long-term exposure, nearly all quasi-experimental evidence on the effects of pollution on health exploits changes in short-term exposure. Quantifying long-run exposure impacts requires a lasting, exogenous change in ambient pollution. Even if the initial change in pollution is exogenous, the long-run nature allows more time for economic agents to respond to changes in pollution, resulting in endogenous pollution exposure. We estimate the effects of long-run pollution exposure on mortality among adults by exploiting the United States Acid Rain Program (ARP) as a natural experiment. The ARP, which regulated emissions from coal power plants, created a permanent change in pollution across vast distances, enabling us to define broad treatment areas to subsume many potential confounding effects. We use a difference-indifferences design, comparing changes in mortality over time in counties “near” regulated plants to changes in mortality in similar counties “far” from the plants. We find relative mortality in treatment counties decreased after the introduction of the ARP, with mortality improvements growing steadily over time in both economic and statistical significance. The ARP had no significant effect on residential sorting or employment, helping rule out selection or economic mechanisms. Analysis by cause of death supports the role of fine particulate matter as the relevant pollutant.
Do Extrinsic Incentives Undermine Social Norms? Evidence from a Field Experiment in Energy Conservation
José Pellerano et al.
Environmental and Resource Economics, July 2017, Pages 413–428
Policymakers use both extrinsic and intrinsic incentives to induce consumers to change behavior. This paper investigates whether the use of extrinsic financial incentives is complementary to intrinsic incentives, or whether financial incentives undermine the effect of intrinsic incentives. We conduct a randomized controlled trial that uses information interventions to residential electricity customers to test this question. We find that adding economic incentives to normative messages not only does not strengthen the effect of the latter but may reduce it. These results are consistent with recent theoretical work that suggests a tension between intrinsic motivation and extrinsic incentives.
Gasoline cars produce more carbonaceous particulate matter than modern filter-equipped diesel cars
S.M. Platt et al.
Scientific Reports, July 2017
Carbonaceous particulate matter (PM), comprising black carbon (BC), primary organic aerosol (POA) and secondary organic aerosol (SOA, from atmospheric aging of precursors), is a highly toxic vehicle exhaust component. Therefore, understanding vehicle pollution requires knowledge of both primary emissions, and how these emissions age in the atmosphere. We provide a systematic examination of carbonaceous PM emissions and parameterisation of SOA formation from modern diesel and gasoline cars at different temperatures (22, −7 °C) during controlled laboratory experiments. Carbonaceous PM emission and SOA formation is markedly higher from gasoline than diesel particle filter (DPF) and catalyst-equipped diesel cars, more so at −7 °C, contrasting with nitrogen oxides (NOX). Higher SOA formation from gasoline cars and primary emission reductions for diesels implies gasoline cars will increasingly dominate vehicular total carbonaceous PM, though older non-DPF-equipped diesels will continue to dominate the primary fraction for some time. Supported by state-of-the-art source apportionment of ambient fossil fuel derived PM, our results show that whether gasoline or diesel cars are more polluting depends on the pollutant in question, i.e. that diesel cars are not necessarily worse polluters than gasoline cars.
Productivity Effects of Air Pollution: Evidence from Professional Soccer
Andreas Lichter, Nico Pestel & Eric Sommer
Labour Economics, October 2017, Pages 54-66
We estimate the causal effect of ambient air pollution on individual productivity using panel data on the universe of professional soccer players in Germany over the period from 1999 to 2011 matched to hourly information on the concentration of particulate matter near each stadium at the time of kick-off. We exploit exogenous variation in players’ exposure to air pollution due to match scheduling rules that are beyond the control of teams and players. The results of our analysis reveal statistically significant negative effects of air pollution on players’ productivity, measured by the total number of passes per match. Allowing for a non-linear dose-response relationship further reveals that our findings are not driven by extreme levels of air pollution. Rather, negative effects already emerge at moderate levels.
Biological annihilation via the ongoing sixth mass extinction signaled by vertebrate population losses and declines
Gerardo Ceballos, Paul Ehrlich & Rodolfo Dirzo
Proceedings of the National Academy of Sciences, 25 July 2017, Pages E6089–E6096
The population extinction pulse we describe here shows, from a quantitative viewpoint, that Earth’s sixth mass extinction is more severe than perceived when looking exclusively at species extinctions. Therefore, humanity needs to address anthropogenic population extirpation and decimation immediately. That conclusion is based on analyses of the numbers and degrees of range contraction (indicative of population shrinkage and/or population extinctions according to the International Union for Conservation of Nature) using a sample of 27,600 vertebrate species, and on a more detailed analysis documenting the population extinctions between 1900 and 2015 in 177 mammal species. We find that the rate of population loss in terrestrial vertebrates is extremely high—even in “species of low concern.” In our sample, comprising nearly half of known vertebrate species, 32% (8,851/27,600) are decreasing; that is, they have decreased in population size and range. In the 177 mammals for which we have detailed data, all have lost 30% or more of their geographic ranges and more than 40% of the species have experienced severe population declines (>80% range shrinkage). Our data indicate that beyond global species extinctions Earth is experiencing a huge episode of population declines and extirpations, which will have negative cascading consequences on ecosystem functioning and services vital to sustaining civilization. We describe this as a “biological annihilation” to highlight the current magnitude of Earth’s ongoing sixth major extinction event.
Where to drill? The petroleum industry’s response to an endangered species listing
Energy Economics, August 2017, Pages 320-327
This paper examines the effect of U.S. Endangered Species Act (ESA) regulations on oil and natural gas well drilling in Kansas and Oklahoma. In 2014 and 2015, petroleum companies faced land use restrictions when the imperiled lesser prairie chicken received threatened species-status under the ESA. In Kansas and Oklahoma, as elsewhere, the petroleum industry has been criticized for damaging environmental quality and developing wildlife habitat. Using data on well locations, I estimate a discrete choice model to measure the effects of ESA regulations on companies’ location preferences. While the results show habitat avoidance increased with regulatory scrutiny, the effect is very modest, which suggests companies may have discounted the risk of penalties from ESA violations. Results also suggest that pre-listing announcements related to ESA regulations influenced companies’ location choice.
Natural Hazards and Local Development: The Successive Nature of Landscape Transformation in the United States
James Elliott & Matthew Thomas Clement
Social Forces, forthcoming
The built environment that serves as the literal foundation for social life involves not just the material development of local landscapes but ongoing damage from natural hazards endemic to these landscapes, which are forecasted to increase over coming years. Prior research has investigated each of these dynamics independently but not their intersection. The present study begins to fill this gap by combining county-level data on land development with that on natural hazard damage to assess how these two dimensions of local landscape transformation unfold together over time. Results from spatial panel regression and structural equation models indicate that on average and net of past trends and time-invariant factors, natural hazard damages tend to accelerate local land development in ways that feed back and scale up successively over time, especially onto formerly undeveloped lands. Implications for future landscape transformation and research are discussed.
Tundra uptake of atmospheric elemental mercury drives Arctic mercury pollution
Daniel Obrist et al.
Nature, 13 July 2017, Pages 201–204
Anthropogenic activities have led to large-scale mercury (Hg) pollution in the Arctic. It has been suggested that sea-salt-induced chemical cycling of Hg (through ‘atmospheric mercury depletion events’, or AMDEs) and wet deposition via precipitation are sources of Hg to the Arctic in its oxidized form (Hg(II)). However, there is little evidence for the occurrence of AMDEs outside of coastal regions, and their importance to net Hg deposition has been questioned. Furthermore, wet-deposition measurements in the Arctic showed some of the lowest levels of Hg deposition via precipitation worldwide, raising questions as to the sources of high Arctic Hg loading. Here we present a comprehensive Hg-deposition mass-balance study, and show that most of the Hg (about 70%) in the interior Arctic tundra is derived from gaseous elemental Hg (Hg(0)) deposition, with only minor contributions from the deposition of Hg(II) via precipitation or AMDEs. We find that deposition of Hg(0) — the form ubiquitously present in the global atmosphere — occurs throughout the year, and that it is enhanced in summer through the uptake of Hg(0) by vegetation. Tundra uptake of gaseous Hg(0) leads to high soil Hg concentrations, with Hg masses greatly exceeding the levels found in temperate soils. Our concurrent Hg stable isotope measurements in the atmosphere, snowpack, vegetation and soils support our finding that Hg(0) dominates as a source to the tundra. Hg concentration and stable isotope data from an inland-to-coastal transect show high soil Hg concentrations consistently derived from Hg(0), suggesting that the Arctic tundra might be a globally important Hg sink. We suggest that the high tundra soil Hg concentrations might also explain why Arctic rivers annually transport large amounts of Hg to the Arctic Ocean.
Characterization of Adipogenic Activity of House Dust Extracts and Semi-Volatile Indoor Contaminants in 3T3-L1 Cells
Christopher Kassotis, Kate Hoffman & Heather Stapleton
Environmental Science & Technology, 1 August 2017, Pages 8735–8745
Obesity and metabolic disorders are of great societal concern and generate significant human health care costs. Recently, attention has focused on the potential for environmental contaminants to act as metabolic disruptors. This study sought to evaluate the adipogenic activity of indoor house dust extracts and a suite of semivolatile organic chemicals (SVOCs) that are often ubiquitously detected in indoor environments. 3T3-L1 cells were exposed to extracts of indoor dust or individual SVOCs and assessed for triglyceride accumulation and preadipocyte proliferation. Ten of 11 house dust extracts exhibited significant triglyceride accumulation and/or proliferation at environmentally relevant levels (<20 μg of dust/well), and significant adipogenic activity was also exhibited by 28 of the SVOCs. Notably, pyraclostrobin, dibutyl phthalate, tert-butyl-phenyl diphenyl phosphate, and the isopropylated triaryl phosphates (ITPs) exhibited near maximal or supra-maximal triglyceride accumulation relative to the rosiglitazone-induced maximum. The adipogenic activity in house dust occurred at concentrations below EPA estimated child exposure levels, and raises concerns for human health impacts, particularly in children. Our results delineate a novel potential health threat and identify putative causative SVOCs that are likely contributing to this activity.
Referenda Under Oath
Nicolas Jacquemet et al.
Environmental and Resource Economics, July 2017, Pages 479–504
Herein we explore whether a solemn oath can eliminate hypothetical bias in a voting referenda, a popular elicitation mechanism promoted in non-market valuation exercises for its incentive compatibility properties. First, we reject the null hypothesis that a hypothetical bias does not exist. Second, we observe that people who sign an oath are significantly less likely to vote for the public good in a hypothetical referenda. We complement this evidence with a self-reported measure of honesty which confirms that the oath increases truthfulness in answers. This result opens interesting avenues for improving the elicitation of preferences in the lab and beyond.
Bicycle infrastructure and traffic congestion: Evidence from DC's Capital Bikeshare
Timothy Hamilton & Casey Wichman
Journal of Environmental Economics and Management, forthcoming
This study explores the impact of bicycle-sharing infrastructure on urban transportation. We estimate a causal effect of the Capital Bikeshare on traffic congestion in the metropolitan Washington, D.C., area. We exploit a unique traffic dataset that is finely defined on a spatial and temporal scale. Our approach examines within-city commuting decisions as opposed to traffic patterns on major thruways. Empirical results suggest that the availability of a bikeshare reduces traffic congestion upwards of 4% within a neighborhood. In addition, we estimate heterogeneous treatment effects using panel quantile regression. Results indicate that the congestion-reducing impact of bikeshares is concentrated in highly congested areas.