Epa's Criteria Pollutants: Is Carbon Dioxide One?

Carbon dioxide (CO2) is a greenhouse gas and the most significant pollutant responsible for climate change. While the Environmental Protection Agency (EPA) has the mandate to regulate pollutants, carbon dioxide is not listed as a criteria pollutant under the Clean Air Act (CAA). The EPA has set air quality standards for six common criteria pollutants: particulate matter, ozone, sulfur dioxide, nitrogen dioxide, carbon monoxide, and lead. These pollutants are known to harm human health and the environment, and cause property damage. However, with new language in the IRA defining carbon dioxide as a pollutant, the EPA now has the authority to regulate carbon dioxide emissions and encourage the adoption of renewable energy sources.

Carbon dioxide is not a listed criteria pollutant

The Clean Air Act requires the EPA to set National Ambient Air Quality Standards (NAAQS) for these six commonly found air pollutants, also known as criteria air pollutants. The EPA has attempted to curb carbon dioxide emissions in the spirit of the Clean Air Act's intent to protect public health and air quality. However, there has been a long history of legal challenges to these attempts.

The Clean Air Act has not undergone any major revisions in the last 30 years. As a result, the EPA does not have a stated mandate to fight climate change, despite scientific consensus on the issue. While carbon dioxide is not listed as a criteria pollutant, it is now legally recognised as a pollutant. This gives the EPA the authority to regulate greenhouse gases and push for the adoption of renewable energy sources.

The EPA's criteria air pollutants are regulated due to their impact on human health and the environment. These pollutants are found all over the US and can cause harm to health, the environment, and property damage. The EPA works with state, tribal, and local air agencies to attain the National Ambient Air Quality Standards throughout the country.

Criteria pollutants are regulated due to their impact on human health and the environment

The Environmental Protection Agency (EPA) has identified six criteria air pollutants that are regulated due to their impact on human health and the environment. These pollutants are carbon monoxide, sulfur dioxide, nitrogen dioxide, lead, ozone, and particulate matter.

Carbon monoxide (CO) is a colorless, odorless, and toxic gas that is harmful to human health, particularly through its interference with the oxygen-carrying capacity of blood, which can lead to serious health issues and even death. Sulfur dioxide (SO2) is a highly reactive gas emitted primarily by industrial sources and power plants burning sulfur-containing fuels. It is harmful to human health, particularly the respiratory system, and causes environmental damage to vegetation. Nitrogen dioxide (NO2) is another highly reactive gas released during fuel combustion, contributing to the formation of other pollutants and posing risks to human health, especially the respiratory system.

Lead (Pb) is a toxic heavy metal that can accumulate in the body over time, causing serious health issues such as damage to the brain, kidneys, and nervous system. Ozone (O3), or ground-level ozone, is formed through chemical reactions involving other pollutants and is harmful to human health, increasing the risk of asthma attacks and lung infections. Lastly, particulate matter, also known as particle pollution, refers to a mixture of solid and liquid particles in the air, which can have adverse effects on human health and the environment.

While carbon dioxide (CO2) is not listed as a criteria pollutant by the EPA, it is now legally recognized as a pollutant. The EPA has attempted to curb carbon dioxide emissions to protect public health and air quality, facing legal challenges from conservative groups. With recent changes in language, the EPA has gained more authority to regulate greenhouse gases and promote renewable energy sources.

The Clean Air Act requires the EPA to set National Ambient Air Quality Standards

The Clean Air Act (CAA) is a comprehensive federal law that regulates air emissions from stationary and mobile sources. It was established in 1970 and has since undergone major revisions in 1977, 1990, and 2022. The Act recognises the right to healthy air quality for all Americans and tasks the Environmental Protection Agency (EPA) with overseeing its implementation.

The NAAQS program sets standards for concentrations of specific pollutants in outdoor air, including ground-level ozone (O3), carbon monoxide (CO), particulate matter (PM10, PM2.5), lead (Pb), sulfur dioxide (SO2), and nitrogen dioxide (NO2). These are known as the six criteria pollutants. The EPA added lead to the list of criteria pollutants after litigation in 1976.

The Clean Air Act Amendments of 1970 significantly expanded the federal mandate by requiring comprehensive federal and state regulations for both industrial and mobile sources. This included the establishment of the NAAQS, New Source Performance Standards (NSPS), and National Emissions Standards for Hazardous Air Pollutants (NESHAPs). The 1977 and 1990 amendments introduced new goals and deadlines for achieving NAAQS, as many areas of the country had failed to meet the initial targets.

While carbon dioxide (CO2) is recognised as the most significant pollutant contributing to climate change, it is important to note that CO2 emissions are not specifically identified as a pollutant in the CAA. As a result, no air quality standards for CO2 levels have been legally established. However, the EPA has repeatedly attempted to curb carbon dioxide emissions in alignment with the CAA's intent to safeguard public health and air quality. The recent inclusion of new language in the IRA defines carbon dioxide as a pollutant, providing the EPA with explicit authority to regulate greenhouse gases and promote renewable energy sources.

The EPA has attempted to curb carbon dioxide emissions

Regulatory Actions and Initiatives

The EPA has implemented several regulatory actions and initiatives to reduce greenhouse gas emissions, including carbon dioxide:

• Renewable Fuel Standard Program: This program aims to reduce greenhouse gas emissions and expand the use of renewable fuels, such as those derived from plants and biomass, while decreasing the reliance on imported oil.
• International Carbon Dioxide Emissions Standards for Aircraft: Working with the Federal Aviation Agency and the UN's International Civil Aviation Organization (ICAO), the EPA has established international standards for carbon dioxide emissions from aircraft, aligning with ICAO standards.
• Emission Standards for Passenger Cars and Light Trucks: In December 2021, the EPA finalized stringent greenhouse gas emission standards for passenger cars and light trucks for model years 2023-2026, leveraging advancements in clean car technology.
• Emission Standards for Fossil Fuel-Fired Power Plants: In 2015, the EPA issued emission standards for greenhouse gas emissions from new fossil fuel-fired utility boilers and natural gas-fired stationary combustion turbines. In May 2024, the EPA published final carbon pollution standards for power plants, setting CO2 limits.
• Methane Emissions Reduction: In 2016, the EPA updated the New Source Performance Standards (NSPS) and guidelines for landfills to reduce methane emissions, implementing a Federal Plan in May 2021.
• HFC Phase-Down: The American Innovation and Manufacturing (AIM) Act of 2020 directed the EPA to address hydrofluorocarbons (HFCs) by phasing down their production and consumption and facilitating a transition to HFC-free technologies. The EPA's HFC Allocation program aims to reduce HFC production and consumption by 85% by 2036.

Clean Air Act (CAA) and Criteria Air Pollutants

The Clean Air Act, established in 1970 and revised in 1977 and 1990, requires the EPA to set National Ambient Air Quality Standards (NAAQS) for six common criteria air pollutants: particulate matter, ozone, sulfur dioxide, nitrogen dioxide, carbon monoxide, and lead. While carbon dioxide is not among these criteria pollutants, the EPA still recognizes its role as the most significant pollutant contributing to climate change.

Despite facing legal challenges, the EPA continues to work within the spirit of the CAA to protect public health and air quality by attempting to curb carbon dioxide emissions. The recent definition of carbon dioxide as a pollutant gives the EPA additional authority to regulate greenhouse gases and promote renewable energy sources.

The EPA can now regulate greenhouse gases

The Environmental Protection Agency (EPA) has long recognised six criteria air pollutants: particulate matter (or particle pollution), ozone (including ground-level ozone), sulfur dioxide, nitrogen dioxide, carbon monoxide, and lead. These pollutants are known to harm human health and the environment and cause property damage.

While carbon dioxide (CO2) is the most significant pollutant responsible for climate change, it was not previously identified as a pollutant in the Clean Air Act (CAA) and no air quality standards for CO2 levels have been legally set. The EPA has repeatedly attempted to curb carbon dioxide emissions in the spirit of the CAA's intent to protect public health and air quality. However, these attempts have been met with legal challenges.

Now, carbon dioxide has been legally defined as a pollutant, giving the EPA the authority to regulate greenhouse gases. This new language specifically addresses the justification that Congress never granted the EPA broad authority to shift America away from burning fossil fuels. With this new language to fall back on, the EPA can reasonably expect to block future legal challenges to any action it takes to regulate CO2 and encourage sustainable energy.

The EPA can now use its power to push for the adoption of wind, solar, and other renewable energy sources. It will be interesting to see what steps the EPA takes to address carbon dioxide emissions and encourage sustainable practices in the United States.

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