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How would reducing tailpipe and smokestack emissions impact health in the Northwest?
In addition to the climate benefits of reducing emissions, achieving net-zero emissions by 2050 also reduces pollutant emissions that have a direct health impact on Northwest residents.
If the region were to achieve net-zero emissions based on the Net-Zero Northwest (NZNW) Energy Pathways Core Case, Northwest residents would experience fewer deaths, fewer days of work lost, and fewer hospital admissions attributed to annual pollutant reductions.
Learn how reducing tailpipe and smokestack emissions would impact health in the Northwest by reading Health Impacts Key Findings or exploring the Pollutant Emissions results.
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Removing coal from the economy and electrifying transportation leads to health benefits in the Northwest.
Coal-fired power plants, which retire by 2030 in the Core Case, contribute to high levels of particulate matter. Removing coal from the economy therefore significantly decreases particulate matter and improves health outcomes in 2030 and beyond. There are also health benefits from reducing vehicle tailpipe emissions through vehicle electrification, especially for heavy trucks that use diesel, which is a large contributor to harmful air pollutants.
The figure below shows the avoided deaths, per million people, that are attributed to reductions in pollutant emissions. The higher health benefits in Washington are due to greater population density, as well as the higher pollutant emissions from the state's transportation and industrial sectors. The figure reports low and high estimates to reflect the range of findings in the epidemiological studies of health outcomes used in the modeling.
Improved health attributed to annual pollutant reductions yield economic benefits for the Northwest.
The NZNW Health Impacts analysis also translates health metrics into economic benefits using assumptions about the economic costs of each type of health impact. Based on the avoided deaths, in addition to the fewer days of work lost and fewer hospital admissions attributed to pollutant emissions reductions, the Northwest could see economy-wide savings of up to $6.2 billion per year in 2030 up to $8.9 billion per year in 2050, with exact values differing by states as seen below:
Racial-ethnic minorities are disproportionately exposed to fine particulate matter in the United States.
While the NZNW Health Impacts analysis does not model health outcomes for specific demographics, understanding unequal exposure to air pollution and fine particulate matter (PM2.5) is critically important. Exposure varies based on proximity to emission sources, and due to the legacy of unequal and unjust housing policies, as well as other factors, disparities exist for people of color in the United States. Despite an overall trend toward cleaner air quality, nationally people of color are exposed to 14% higher levels of PM2.5 than the population average and 25% higher than white people.
Beyond the climate benefits, health impacts and related cost savings offer support for achieving net-zero emissions.
Health outcomes and their subsequent economic impacts are co-benefits to actions taken to reduce greenhouse gases. If optimizing for air quality rather than meeting greenhouse gas emissions targets, a state could employ different strategies to further reduce pollutant emissions. Furthermore, greenhouse gas reductions beyond net-zero could be cost-effective if health outcomes and their economic benefits are included.
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The NZNW Energy Pathways analysis modeled a Core Case that examines low-cost pathways for how the Northwest could achieve economy-wide net-zero emissions by 2050. In addition to the climate benefits of reducing both carbon dioxide (CO2) and non-CO2 emissions, achieving net-zero emissions by 2050 also reduces pollutant emissions that have a direct health impact for Northwest residents.
The Core Case results in air quality improvements due to reduced pollutant emissions from point sources, such as coal-fired electricity power plants, and non-point sources, such as vehicle tailpipe emissions and agriculture.
To produce the NZNW Health Impacts analysis, Evolved Energy Research (Evolved) used the U.S. Environmental Protection Agency (EPA)’s Co-Benefits Risk Assessment model (COBRA), which determines the health benefits and economic impacts of changes in fine particulate matter (PM2.5) concentrations, as well as secondary particulate matter that can be formed by atmospheric reactions of nitrous oxides (NOx), sulfur dioxide (SO2), ammonia (NH3), and volatile organic compounds (VOCs). (The COBRA model does not account for the health impact of direct exposure to ozone, which can also cause health damage but on a smaller scale than particulate matter).
These pollutants all can cause negative health effects, primarily harming the respiratory system or aggravating respiratory diseases:
Particulate matter contains microscopic solids or liquid droplets that can cause health problems when inhaled, especially those that are less than 2.5 micrometers in diameter (PM2.5).
SO2 is the predominant form of gaseous sulfur oxides (SOx) and largely comes from fossil fuel combustion in power plants and other industrial facilities.
NOx emissions are primarily caused by transportation (vehicles and trucks, as well as construction equipment and boats) and industrial facilities.
NH3 emissions are largely from agriculture.
VOCs are mostly human-made chemicals used in paints, pharmaceuticals, and refrigerants.
The NZNW Health Impacts analysis starts with changes in emissions from electricity, vehicles, and other sectors of the economy relative to a baseline. Emissions reductions are assessed using Evolved’s EnergyPATHWAYS and RIO models for the Core Case as depicted below (see Assumptions tab for more information on data development).
After assessing the changes in emissions, the model passes those changes to COBRA to develop air quality scenarios. These determine impacts to air quality and the subsequent health outcomes and economic benefits of reducing pollutant emissions.
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After developing air quality scenarios, the COBRA model uses health impact functions collected from numerous epidemiological studies to translate the changes in total PM2.5 (including secondary PM2.5) into health outcomes and estimates the health impact of changes in outdoor air quality.
Finally, COBRA translates these health metrics into economic benefits using assumptions about the economic costs of each type of health impact. Costs are sourced from the value of statistical life (VSL), cost of illness, hospital charges, willingness to pay to avoid illness, activity restriction, and lost workdays to determine the economic impacts of these health outcomes. For more information on how the monetary values for each health outcome are determined, see Appendix F of the EPA's COBRA User’s Manual.
For additional details on the COBRA methodology, see the EPA's COBRA FAQ document, and for a full description of Evolved's methodology, see pages 196-200 in the Energy Pathways Technical Report.
The NZNW Energy Pathways analysis modeled a Core Case that examines low-cost pathways for how the Northwest could achieve economy-wide net-zero emissions by 2050. In addition to the climate benefits of reducing both carbon dioxide (CO2) and non-CO2 emissions, achieving net-zero emissions by 2050 also reduces pollutant emissions that have a direct health impact for Northwest residents.
To produce the NZNW Health Impacts analysis, Evolved Energy Research (Evolved) used the U.S. Environmental Protection Agency (EPA)’s Co-Benefits Risk Assessment model (COBRA), which determines health benefits and economic impacts of changes in pollutant emissions.
The NZNW Energy Pathways modeling assumes emissions reduction targets across the United States, including targets set by states where available, as well as 40% of 1990 emissions by 2030 and net-zero emissions by 2050 in states without targets. Emissions reductions in the COBRA model are therefore present not only in the Northwest, but also in surrounding states. This assumption increases improvement in health outcomes in the Northwest because in-state concentrations of pollutants are impacted by air flows from outside the state.
The NZNW Health Impacts analysis starts with changes in emissions from electricity, vehicles, and other sectors of the economy relative to a baseline. Evolved uses modeled emissions from the year 2021 as the baseline, and changes in emissions in 2030 and 2050 are therefore relative to 2021. Emissions reductions are assessed using Evolved’s EnergyPATHWAYS and Regional Investment and Operations model (RIO) models for the NZNW Energy Pathways Core Case:
EnergyPATHWAYS
Energy demand-side technology emission changes
On the demand side, the transition to electric vehicles over time reduces tail pipe emissions, which are calculated from the vehicle miles traveled of internal combustion powered-vehicles in future years. EnergyPATHWAYS calculates emissions based on technology activity.
Database of emissions factors for nitrous oxides (NOx), PM2.5, and sulfur oxides (SOx) from key technologies:
Vehicles emission factors taken from the EPA MOtor Vehicle Emission Simulator (MOVES)
Supplemental vehicle emission data from Organisation for Economic Cooperation and Development (OECD)’s Non-exhaust Particulate Emissions from Road Transport (2020)
Building technologies adapted from EPA’s Air Emissions Inventories for point sources
Can include additional criteria pollutant emission factors as data sources allow
RIO
Energy supply-side emission changes
On the supply side, RIO incorporates the database of emissions factors for new and existing plants. Based on the dispatch of thermal generation in each year, the model determines total pollution from electricity generation. RIO calculates emissions based on least-cost dispatch.
Database of emissions factors for NOx, PM2.5, SOx, and mercury from existing and new power plants:
Existing plant emission factors taken from EPA’s AVoided Emissions and geneRation Tool (AVERT) and Emissions & Generation Resource Integrated Database (eGRID) 2019 data
Existing energy conversion technologies (e.g., boilers for steam) are adapted from EPA’s Air Emissions Inventories for point sources
New power plant data is a combination of National Renewable Energy Laboratory (NREL)’s Annual Technology Baseline (ATB) data and EPA’s National Electric Energy Data System data (NEEDS)
Can include additional criteria pollutant emission factors as data sources allow
For a full description of Evolved's assumptions, see the Energy Pathways Technical Report.
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