Epa's Stance On Carbon Dioxide: A Pollutant Or Not?

The Environmental Protection Agency (EPA) is tasked with protecting human health and the environment. While the EPA does not have a stated mandate to fight climate change, it does have a mandate to regulate pollutants. The EPA has set air quality standards for six common criteria pollutants: particulate matter, ozone, sulfur dioxide, nitrogen dioxide, carbon monoxide, and lead. Carbon dioxide (CO2) is the most significant pollutant responsible for climate change, but interestingly, CO2 emissions are not specifically identified as a pollutant in the Clean Air Act (CAA), and no air quality standards for CO2 levels have been legally set. However, in 2022, the U.S. Supreme Court ruled that the EPA does not have the authority to regulate CO2 emissions from existing power plants. This ruling has sparked debates about the EPA's ability to address climate change effectively.

The EPA's statutory authority to regulate CO2 emissions

In 2007, the US Supreme Court decided that the EPA has the statutory authority to regulate greenhouse gas emissions from new motor vehicles. This was a split ruling, with five judges voting in favor and four dissenting. The Court decided that greenhouse gases fit the Clean Air Act's (CAA) definition of "air pollutant", and that the EPA must reconsider its decision to not regulate GHG emissions. The EPA Administrator, in 2009, found that greenhouse gases endanger public health and welfare, and that emissions from motor vehicles contribute to that threat.

The EPA has set air quality standards for six common criteria pollutants: particulate matter, ozone, sulfur dioxide, nitrogen dioxide, carbon monoxide, and lead. While carbon dioxide (CO2) is not specifically identified as a pollutant in the CAA, the EPA has repeatedly attempted to curb carbon dioxide emissions to protect public health and air quality.

In 2010, the EPA modified the applicability criteria in the Prevention of Significant Deterioration and Title V Greenhouse Gas Tailoring Rule (Tailoring Rule). The major source regulatory threshold for GHGs was raised from 100/250 tons per year to 100,000 tons per year of CO2 equivalent emissions. This was done to prevent the unbearable administrative burden associated with the PSD program.

The Inflation Reduction Act of 2022 (IRA) lays the legal foundation for stronger federal oversight of emissions most significant to climate change, including CO2. The IRA includes measures such as tax credits for electric vehicles and rebates for energy-efficient appliances. It also includes a provision that amends the Clean Air Act.

The EPA has also drafted regulations for greenhouse gas emissions from existing and new fossil fuel-fired electric generating units, known as the Affordable Clean Energy Rule. However, there is evidence that suggests the negative impact of GHG emissions has grown since 2009, and Americans are experiencing the worsening effects of climate change.

The Clean Air Act and National Ambient Air Quality Standards

The Clean Air Act (CAA) is a comprehensive federal law that regulates air emissions from stationary and mobile sources. The Environmental Protection Agency (EPA) was established by Congress in 1970, and the CAA was last amended in 1990. The CAA requires the EPA to establish National Ambient Air Quality Standards (NAAQS) to protect public health and welfare and to regulate emissions of hazardous air pollutants. The NAAQS are selected by the U.S. EPA Administrator at the conclusion of a public process that takes about five years. The process starts with a comprehensive review of the relevant scientific literature, which is summarized in a document called the Integrated Science Assessment (ISA). Based on the ISA, the EPA performs a risk and exposure assessment, which is summarized in the Risk and Exposure Assessment (REA) document. The third document, the Policy Assessment (PA), integrates the findings and conclusions of the ISA and REA into a policy context and provides lines of reasoning for the retention or revision of existing NAAQS. Each of these three documents is released for public comment and peer review by the Clean Air Scientific Advisory Committee (CASAC). The CASAC is a subcommittee of the EPA, and its role is to ensure that the NAAQS documents reflect the thinking of the scientific community and advise the Administrator on technical and scientific aspects. Once all three documents are finalized, they are given to the EPA Administrator to select a proposed NAAQS, which is released through the Federal Register for public comment. Following the close of the comment period, the Administrator considers the comments received and makes changes to the proposed NAAQS if warranted. The final NAAQS is then published in the Federal Register.

The Clean Air Act Amendments of 1970 instructed the EPA to set primary NAAQS to protect public health and secondary NAAQS to protect plants, forests, crops, and materials from damage due to air pollution. The primary standards provide public health protection, including for "sensitive" populations such as asthmatics, children, and the elderly. The secondary standards provide public welfare protection, including protection against decreased visibility and damage to animals, crops, vegetation, and buildings. The Act was amended in 1977 and 1990 to set new goals (dates) for achieving NAAQS, as many areas of the country had failed to meet the previous deadlines.

While the CAA does not specifically identify CO2 emissions as a pollutant, the EPA does have a mandate to regulate pollutants and has repeatedly attempted to curb CO2 emissions to protect public health and air quality. In 2022, the Inflation Reduction Act (IRA) included a provision that amended the CAA and laid the legal foundation for stronger federal oversight of emissions most significant to climate change, including CO2. The Supreme Court also decided that greenhouse gases, including CO2, fit within the CAA's definition of "air pollutant", giving the EPA statutory authority to regulate these emissions.

CO2 as a greenhouse gas

Carbon dioxide (CO2) is a greenhouse gas that enters the Earth's atmosphere through the burning of fossil fuels (coal, natural gas, and oil), solid waste, trees and other biological materials, and also as a result of certain chemical reactions (e.g. cement production). CO2 is the most significant pollutant responsible for climate change.

CO2 is a greenhouse gas because it absorbs and radiates heat. Greenhouse gases absorb heat radiating from the Earth's surface and re-release it in all directions, including back towards the Earth's surface. This is known as the greenhouse effect, which is essential for making Earth's climate habitable. Without any carbon dioxide, Earth's natural greenhouse effect would be too weak to keep the average global surface temperature above freezing.

However, by adding more carbon dioxide to the atmosphere, humans are amplifying the natural greenhouse effect, causing global temperatures to rise. This is known as global warming or climate change. According to observations by the NOAA Global Monitoring Laboratory, carbon dioxide alone is responsible for about 80% of the total heating influence of all human-produced greenhouse gases since 1990.

The concentration of CO2 in the Earth's atmosphere has been increasing significantly due to human activities. In 2019 alone, humans emitted 36.44 billion tons of CO2 into the atmosphere, and the annual rate of increase in atmospheric carbon dioxide over the past 60 years is 100-200 times faster than the increase that occurred at the end of the last ice age 11,000-17,000 years ago.

To address this issue, the Inflation Reduction Act of 2022 (IRA), also known as the "climate bill," includes measures to promote sustainable technology and businesses, such as tax credits for electric vehicles and residential solar arrays. Additionally, the U.S. Environmental Protection Agency (EPA) has been granted the authority to regulate greenhouse gas emissions, including CO2, which is now legally defined as a pollutant.

CO2 emissions from existing power plants

The US Environmental Protection Agency (EPA) is tasked with protecting human health and the environment. While the EPA does not have a stated mandate to fight climate change, it does have a mandate to regulate pollutants.

The EPA has set air quality standards for six common criteria pollutants: particulate matter (or particle pollution), ozone, sulfur dioxide, nitrogen dioxide, carbon monoxide, and lead. Although carbon dioxide (CO2) is not listed as a pollutant, it is the most significant pollutant responsible for climate change.

CO2 enters the atmosphere through burning fossil fuels (coal, natural gas, and oil), solid waste, trees and other biological materials, and also as a result of certain chemical reactions (e.g., cement production). Nuclear power generation, on the other hand, emits negligible CO2, and renewable energy sources such as wind and solar produce about one-third of the CO2-equivalent emissions per unit of electricity as nuclear.

The EPA has attempted to curb carbon dioxide emissions in the spirit of the Clean Air Act's (CAA) intent to protect public health and air quality. The Inflation Reduction Act of 2022 (IRA) has also laid the legal foundation for stronger federal oversight of emissions most significant to climate change, including CO2. This gives the EPA the authority to regulate greenhouse gases and push the adoption of renewable energy sources.

CO2 emissions from motor vehicles

The US Environmental Protection Agency (EPA) is tasked with protecting human health and the environment. While the EPA does not have a stated mandate to fight climate change, it does have a mandate to regulate pollutants. Notably, the EPA has set air quality standards for six common criteria pollutants: particulate matter (or particle pollution), ozone, sulfur dioxide, nitrogen dioxide, carbon monoxide, and lead.

Although carbon dioxide (CO2) is not specifically identified as a pollutant in these standards, it is the most significant pollutant responsible for climate change. CO2 is released into the atmosphere through the burning of fossil fuels (coal, natural gas, and oil), solid waste, trees and other biological materials, and certain chemical reactions (e.g., cement production).

Motor vehicles are a significant contributor to CO2 emissions. According to the EPA, the average passenger vehicle emits about 400 grams of CO2 per mile, or about 4.6 metric tons of CO2 per year. In addition to CO2, automobiles using gasoline produce methane (CH4) and nitrous oxide (N2O) from the tailpipe, and all vehicles can emit hydrofluorocarbon (HFC) from leaking air conditioners.

To reduce CO2 emissions from motor vehicles, there are two main approaches: improving vehicle efficiency and changing the fuel used. Electric vehicles (EVs), for example, have no tailpipe emissions, although emissions are created during the production and distribution of the electricity used to fuel the vehicle. The rise of electric vehicles offers a viable option to reduce emissions from passenger vehicles, with sales of electric vehicles surging in recent years. The EU, for example, has introduced new CO2 emission targets, aiming for zero CO2 emissions for new passenger cars and light commercial vehicles by 2035.

In the US, the Inflation Reduction Act of 2022 (IRA) includes sustainability measures such as tax credits for electric vehicles and residential solar arrays. This legislation provides a legal foundation for stronger federal oversight of emissions most significant to climate change, including CO2.

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