2016 Progress Report: Air Pollutant Control Strategies in a Changing World

EPA Grant Number: R835873C004
Subproject: this is subproject number 004 , established and managed by the Center Director under grant R835873
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: Center for Air, Climate, and Energy Solutions
Center Director: Robinson, Allen
Title: Air Pollutant Control Strategies in a Changing World
Investigators: Hill, Jason , Adams, Peter , Apte, Joshua S. , Azevedo, InĂªs L , Boies, Adam M. , Coggins, Jay S. , Hankey, Steve , Jaramillo, Paulina , Marshall, Julian D. , Matthews, H. Scott , Michalek, Jeremy J. , Millet, Dylan B , Muller, Nicholas , Pandis, Spyros N. , Polasky, Stephen , Robinson, Allen
Institution: Carnegie Mellon University , Middlebury College , The University of Texas at Austin , University of Minnesota , Virginia Polytechnic Institute and State University
EPA Project Officer: Chung, Serena
Project Period: May 1, 2016 through April 30, 2021
Project Period Covered by this Report: May 1, 2016 through April 30,2017
RFA: Air, Climate And Energy (ACE) Centers: Science Supporting Solutions (2014) RFA Text |  Recipients Lists
Research Category: Air , Climate Change


The over-arching objective of Project 4 is to develop and demonstrate a comprehensive policy assessment framework that is both broad (multipollutant) and tall (from scenario specification to emissions to impacts). Specific objectives are: 1) Apply chemical transport and reduced-form air quality models to assess the air quality and health impacts of various technology, policy, land-use, and climate scenarios; 2) Assess alternative policies, technology trajectories, and land-use variations; and 3) Assess statistical, scenario, and model specification uncertainty, determine the degree to which results are sufficiently robust to justify findings and recommendations, and identify key factors that drive uncertainty.

Progress Summary:

During this reporting period, we began our investigation of technology and policy scenarios aimed at identifying actions that improve air quality while limiting climate change. We focused on the Center for Climate, Air, and Energy Solutions' (CACES) four major focus areas: electricity production, transportation, land use, and climate change. The work has resulted in six journal articles in these areas that have been submitted for publication as well as the preparation of additional manuscripts, and the dissemination of results through presentations and engagement with stakeholders.  The results of this work so far are summarized below.

1. United States Economy-Wide PM2.5 Damages

Responsibility for air pollution is commonly attributed to the physical entities that release emissions, such as power plants, factories, farms, and vehicles.  We used an alternative framing to ascribe responsibility for air pollution to the economic demand ultimately driving its release. We estimate air quality-related health effects for each of 428 sectors of the U.S. economy, the largest fractions of which were physically produced by electricity generation but induced by demand for manufactured goods. We explored health equity effects as well, finding that Hispanic and Black populations are disproportionately impacted. This alternative framing of air-quality related health impacts, which reveals the embodied health impacts of economic consumption, offers novel opportunities for strategies of air quality improvement.

2. GHG and CAP Emissions Under Future Policy Scenarios

We are focusing on modeling greenhouse gas (GHG) and criteria air pollutant (CAP) emissions under several different future policy scenarios. Specifically, we are comparing the economic efficiency of homogenous versus heterogeneous air pollution regulations in the presence and absence of greenhouse gas regulations in the United States. A primary focus of this research is to examine differences in technology trajectories that could be used to efficiently meet future air-quality regulations, climate emissions regulations, as well as both air-quality and climate regulations in tandem.

We are one of the first research groups to use the EPA’s new TIMES (The Integrated MARKAL-EFOM System) model generator for the United States to produce long-term energy and environment scenarios. The novel aspect of this policy research is the spatial and species resolution that we use. Through the inclusion of the Estimating Air pollution Social Impact Using Regression (EASIUR) and Air Pollution Emission Experiments and Policy analysis (AP2) models, we are developing scenarios including but not limited to: region specific criteria pollutant regulations that vary by source, sector, and marginal damage to the environment, as well as carbon emission caps and taxes. The purpose of this work is to assess the efficiency of regulating emissions homogeneously as is done currently in the United States and compare this status quo to a set of regulations that vary according to the magnitude of damage caused by the emission of a specific species in a specific location.

3. Air Pollution Impacts of Corn Production

Corn is the largest crop grown in the United States and it utilizes approximately 40% of all nitrogen fertilizer inputs. Nitrogen fertilizer application leads to large amounts of ammonia emissions, a potent precursor pollutant to the formation of PM2.5. Using a life-cycle impact analysis (LCIA) approach, we create a spatially explicit emission inventory for corn production in each county, and estimate the damages per bushel of corn produced. We estimate mean damages of $3.27/bu of corn produced in the United States, with 65% from ammonia emissions. Ammonia damages are more than six times larger than damages from GHG emissions. Spatial variation of damages is large, with the least damaging 5% of corn produced with damages less than $1.56/bu, and the most damaging 5% of corn produced with damages more than $6.17/bu.

4. Corn Air Pollution Impact Mitigation from Nitrogen Fertilizer Management

Nitrogen emissions from corn production are released to the air as ammonia, nitric oxide and nitrous oxide and into water systems as nitrates. Damages from nitrogen fluxes in corn production are large, with the largest damages associated with ammonia emissions. Managing nitrogen releases in corn production requires limiting ammonia emissions. Farmers can switch to nitrogen fertilizers with lower ammonia volatilization rates, and reduce application rates. We estimate that in the current baseline, damages from nitrogen losses from Midwest corn production are $14 billion per year, but can be reduced to $7 billion by switching all nitrogen fertilizer to anhydrous ammonia, which has a low volatilization rate. By reducing nitrogen fertilizer application rates from an average of 170 kg N/ha to 108 kg N/ha, damages can be further reduced to $4.3 billion per year.

5. VSL and Mortality Risk Age Adjustments

Estimating monetary valuations of reductions in the risk of mortality is controversial but necessary to evaluate tradeoffs of air pollution policies. Conventional wisdom suggests that adjusting value of a statistical life (VSL) by the age of those impacted greatly reduces the total monetary damages of air pollution. We estimate the impact of including age differences in both the VSL and the risk of mortality. Mortality relative-risks of PM2.5 are higher for younger populations than older populations. When we adjust both the VSL and mortality risk by age the total damages are lower than without an age adjustment, but not dramatically lower as conventional wisdom and past estimates indicate.

6. Life Cycle Air Quality Impacts of Switchgrass Production in the United States

Switchgrass is a promising bioenergy feedstock, but industrial scale production may lead to unintended negative environmental effects. This study considers one such potential consequence; the life-cycle monetized damages of switchgrass production on human health via changes in air quality. Increases in mortality are estimated as being caused by long-term exposure to fine particulate matter (PM2.5), which is emitted directly (“primary PM2.5”) and forms from precursors (“secondary PM2.5”) of nitrogen oxides (NOx), sulfur oxides (SOx), ammonia (NH3), and volatile organic compounds (VOCs). Changes in atmospheric concentrations of PM2.5 from on-site production and supporting supply chain activities are considered at 2,694 locations (counties in the eastern United States), 2 yields (9 and 20 Mg ha-1), 3 N fertilizer rates (50, 100, and 150 kg ha-1), and 2 N fertilizer types (urea and urea ammonium nitrate). Results indicate that on-site processes dominate life-cycle emissions of NH3, NOx, PM2.5, and VOCs, whereas SOx is primarily emitted in upstream supply chain processes. Total air quality impacts of switchgrass production, which are driven by ammonia emissions from fertilizer application, range widely depending on location, from $2 to $553 Mg-1 (mean: $45 Mg-1) of dry switchgrass at a biomass yield of 20 Mg ha-1 and fertilizer application of 100 kg ha-1 N applied as urea. Switching to urea-ammonium nitrate solution lowers damages to $2 to $329 Mg-1 (mean: $28 Mg-1). This work points to human health damage from reduced air quality as a large potential social cost from switchgrass production, and suggests means of mitigating it via strategic geographical deployment and management. Furthermore, by distinguishing the origin of atmospheric emissions, this analysis advances the current emerging literature on ecosystem disservices from agricultural and bioenergy systems.

7. Controlling Secondary Organic Aerosol (SOA) Production from Gasoline Vehicle Emissions

On-road gasoline vehicles are a major source of secondary organic aerosol (SOA) in urban areas. We investigated SOA formation by oxidizing dilute, ambient-level exhaust concentrations from a fleet of on-road gasoline vehicles in a smog chamber. We measured less SOA formation from newer vehicles meeting more stringent emissions standards. This suggests that the natural replacement of older vehicles with newer ones that meet more stringent emissions standards should reduce SOA levels in urban environments. However, SOA production depends on both precursor concentrations (emissions) and atmospheric chemistry (SOA yields). We found a strongly nonlinear relationship between SOA formation and the ratio of non-methane-organic-gas-to-NOx (NMOG:NOx), which affects the fate of peroxy radicals. For example, changing the NMOG:NOx from 4 to 10 ppbC/ppbNOx increased the SOA yield from dilute gasoline-vehicle exhaust by a factor of 8. We investigated the implications of this relationship for the Los Angeles area. Although organic gas emissions from gasoline vehicles in Los Angeles are expected to fall by almost 80% over the next two decades, we predict no reduction in SOA production due to the effects of rising NMOG:NOx on SOA yields. This highlights the importance of integrated emission control policies for NOx and organic gases.

8. Hydrogen Production Pathways and Transportation

In this work we reviewed cost and emissions estimates of a comprehensive set of hydrogen production pathways that analyzes trends and discusses implications for transportation.

Future Activities:

In the subsequent reporting period, we will continue our work in our four major focus areas, with particular attention paid to integration of project personnel to address topics of emerging importance. More specifically:

  • GHG and CAP Emissions Under Future Policy Scenarios

During the next period we will incorporate marginal emissions damage factors at the region and sector level for the first time as part of the EPA’s new 9-region TIMES-MARKAL model. We will expand on the EPA US-TIMES model by incorporating region and sector-specific emissions damage values derived from the Estimating Air pollution Social Impact Using Regression (EASIUR) and the Air Pollution Emission Experiments and Policy analysis (AP2) models. Through the inclusion of the EASIUR and AP2 models, we will develop scenarios including but not limited to: region specific criteria pollutant regulations that vary by source, sector, and marginal damage to the environment, as well as carbon emission caps and taxes.

  • Climate-Dependent Emissions

Biogenic and NH3 emissions: The PMCAMx CTM is connected to the Model of Emissions of Gases and Aerosols from Nature (MEGAN) for calculation of meteorology dependent emissions of isoprene, monoterpenes, and sesquiterpenes. The CMU NH3 emissions model will be used for the corresponding emissions. We will use the available meteorological fields for the United States for 10 years typical of the 2050s and calculate the corresponding biogenic VOC and NH3 inventories.

Wildfire emissions: For the wildfires we will use the 2050 LPJ-GUESS fire emissions dataset. These inventories have been developed based on wildfire emission simulations using the new IPCC AR5 CMIP5 climate simulations, and population scenarios from the new Shared Socio-Economic Pathways. We will use emissions for the RCP8.5 scenario as an extreme case. Emission factors, volatility distributions, and aging parameters will be calculated from the latest laboratory (FLAME studies) and field measurements.

  • Testing of PMCAMx and EASIUR

We are performing simulations with PMCAMx for 2050 to test if the responses of EASIUR that have been derived for the present are robust enough to work for that part of the space. The hypothesis is that the changes are similar to those currently used. If this is not the case, the EASIUR model will be updated for the future chemical regimes.

  • Transportation Sources

We are planning to conduct a number of transportation related studies in the upcoming project period including air pollution implications of shared mobility using (1) econometric analyses and (2) optimization approaches; quantification of the emissions implications of the shift to gasoline direct injection; and expansion of our scope of the vehicle and fuel pathways for which we are assessing life cycle air quality impacts.

Journal Articles on this Report : 4 Displayed | Download in RIS Format

Other subproject views: All 4 publications 4 publications in selected types All 4 journal articles
Other center views: All 20 publications 8 publications in selected types All 8 journal articles
Type Citation Sub Project Document Sources
Journal Article Weis A, Jaramillo P, Michalek J. Consequential life cycle air emissions externalities for plug-in electric vehicles in the PJM interconnection. Environmental Research Letters 2016;11(2):024009 (12 pp.). R835873 (2016)
R835873C004 (2016)
  • Full-text: IOP Science-Full Text PDF
  • Abstract: IOP Science-Abstract & Full Text HTML
  • Other: Research Gate-Abstract & Full Text PDF
  • Journal Article Zhao Y, Saleh R, Saliba G, Presto AA, Gordon TD, Drozd GT, Goldstein AH, Donahue NM, Robinson AL. Reducing secondary organic aerosol formation from gasoline vehicle exhaust. Proceedings of the National Academy of Sciences of the United States of America 2017;114(27):6984-6989. R835873 (2016)
    R835873C004 (2016)
  • Abstract from PubMed
  • Abstract: PNAS-Abstract
  • Other: Harvard University-Abstract
  • Journal Article Muller NZ. Environmental benefit-cost analysis and the national accounts. Journal of Benefit-Cost Analysis 2017;1-40 [Epub ahead of print]. R835873C004 (2016)
  • Abstract:
  • Journal Article Muller NZ, Jha A. Does environmental policy affect scaling laws between population and pollution? Evidence from American metropolitan areas. PLOS One 2017;12(8):e0181407 (15 pp.). R835873C004 (2016)
  • Full-text from PubMed
  • Abstract from PubMed
  • Associated PubMed link
  • Full-text: PLOS ONE-Full Text PDF
  • Abstract: PLOS ONE-Abstract & Full Text HTML
  • Supplemental Keywords:

    Air quality, cost-benefit, decision making, energy, exposure, health effects, integrated assessment, land, life-cycle analysis, public policy, renewable

    Relevant Websites:

    The Center for Air, Climate, and Energy Solutions Exit

    Progress and Final Reports:

    Original Abstract

    Main Center Abstract and Reports:

    R835873    Center for Air, Climate, and Energy Solutions

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R835873C001 Mechanistic Air Quality Impact Models for Assessment of Multiple Pollutants at High Spatial Resolution
    R835873C002 Air Quality Observatory
    R835873C003 Next Generation LUR Models: Development of Nationwide Modeling Tools for Exposure Assessment and Epidemiology
    R835873C004 Air Pollutant Control Strategies in a Changing World
    R835873C005 Health Effects of Air Pollution and Mitigation Scenarios