Air Pollution: What Laws Are Enforced To Protect Us?

Air pollution is an issue that has plagued many countries for decades, with industrialization and car emissions contributing to poor air quality. In response, many countries have implemented laws to combat this issue and protect their citizens' health. One of the most well-known and effective laws is the Clean Air Act (CAA) in the United States, which was enacted in 1970 and has since undergone several amendments. This law gives the Environmental Protection Agency (EPA) the authority to regulate air pollutants and set standards for air quality, with the goal of reducing air pollution and protecting public health. The CAA sets limits on certain air pollutants and regulates emissions from both stationary sources, such as chemical plants and utilities, and mobile sources, including vehicles and non-road engines. Other countries have also implemented similar laws and regulations to tackle air pollution, recognizing the importance of clean air for their citizens' well-being and the environment.

The Clean Air Act (CAA)

The CAA is the comprehensive federal law that regulates air emissions from stationary and mobile sources. It authorizes the EPA to establish National Ambient Air Quality Standards (NAAQS) to protect public health and public welfare, and to regulate emissions of hazardous air pollutants. The NAAQS govern how much ground-level ozone, carbon monoxide, particulate matter, lead, sulfur dioxide, and nitrogen dioxide are allowed in the outdoor air. The Act also gives the EPA the authority to limit emissions of air pollutants from sources like chemical plants, utilities, and steel mills.

The CAA requires major stationary sources to install pollution control equipment and meet specific emissions limitations. "Major sources" are defined as a stationary source or group of stationary sources that emit or have the potential to emit 10 tons per year or more of a hazardous air pollutant, or 25 tons per year or more of a combination of hazardous air pollutants. These emission standards are commonly referred to as "maximum achievable control technology" or "MACT" standards.

The CAA also mandates controls on air pollution from mobile sources by regulating the composition of fuels and emission-control components on motor vehicles and non-road engines. Vehicle fuel standards for gasoline and diesel must be met by refiners/importers and other parties in the fuel distribution system. Regulation of vehicles includes vehicle emission limits for hydrocarbons, carbon monoxide, and nitrogen oxides, and particulates in the case of diesel vehicles.

The Clean Air Act has been amended several times, notably in 1977, 1990, and 2005, to set new goals and deadlines for achieving NAAQS, address specific issues like acid rain and ozone layer depletion, and strengthen enforcement to ensure better compliance with the Act.

National Ambient Air Quality Standards (NAAQS)

The Clean Air Act (CAA) requires the Environmental Protection Agency (EPA) to set National Ambient Air Quality Standards (NAAQS) for six principal pollutants, called "criteria pollutants", that are common in outdoor air, harmful to public health and the environment, and that come from numerous and diverse sources. The six criteria air pollutants are carbon monoxide, ground-level ozone, lead, nitrogen oxides, particulate matter, and sulfur dioxide.

The statute established two types of national air quality standards: primary standards and secondary standards. Primary standards are national ambient air quality standards designed to protect public health with an adequate margin for safety, including protecting the health of "sensitive" populations such as asthmatics, children, and the elderly. Secondary standards are national ambient air quality standards designed to protect the public welfare from adverse effects, including those related to effects on soils, water, crops, vegetation, man-made (anthropogenic) materials, animals, wildlife, weather, visibility, and climate; damage to property; transportation hazards; economic values; and personal comfort and well-being.

NAAQS are selected by the U.S. EPA Administrator at the conclusion of a public process that takes about five years for completion. The process starts with a comprehensive review of the relevant scientific literature. The literature is summarized and conclusions are presented in a document called the Integrated Science Assessment (ISA). Based on the ISA, U.S. EPA staff perform 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 that could be used to support retention or revision of the existing NAAQS, as well as several alternative standards that could be supported by the review findings. Each of these three documents is released for public comment and public peer review by the Clean Air Scientific Advisory Committee (CASAC), a sub-committee of U.S. EPA.

Members of CASAC are appointed by the U.S. EPA Administrator for their expertise in one or more of the subject areas covered in the ISA. The committee’s role is to peer review the NAAQS documents, ensure that they reflect the thinking of the scientific community, and advise the Administrator on the technical and scientific aspects of standard setting. Each document goes through two to three drafts before CASAC deems it to be final. Once all three documents are final, they are given to the U.S. EPA Administrator to use in selecting 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, makes changes to the proposed NAAQS if warranted, and publishes the final NAAQS in the Federal Register. Periodically, the standards are reviewed and sometimes may be revised, establishing new standards.

State Implementation Plans (SIPs)

The Clean Air Act (CAA) is a comprehensive federal law that regulates air emissions from stationary and mobile sources. The Act authorises the Environmental Protection Agency (EPA) to establish National Ambient Air Quality Standards (NAAQS) to protect public health and welfare and to regulate emissions of hazardous air pollutants.

One of the goals of the CAA was to set and achieve NAAQS in every state by 1975 to address the health and welfare risks posed by certain widespread air pollutants. To achieve this, the Act directed states to develop State Implementation Plans (SIPs) to be applied to appropriate industrial sources within the state.

A SIP is a plan for complying with the federal Clean Air Act, administered by the EPA. It is developed by a state agency and approved by the EPA. It consists of narrative, rules, technical documentation, and agreements that a state will use to control and clean up polluted areas. The Lowest Achievable Emissions Rate (LAER) is used by the EPA to determine if emissions from a new or modified major stationary source are acceptable under SIP guidelines. LAER standards are required when a new stationary source is located in a non-attainment air-quality region.

For example, in Ohio between 1970 and 1977, a rule in the Clean Air Act required a reduction in the measured sulfur dioxide (SO2) emitted by coal-fired power plants. The State Implementation Plan to decrease SO2 emissions from these plants was to increase the height of the smokestacks. This resulted in the wind carrying the SO2 out of the state, reducing measured levels in the area near the source. However, in the 1977 amendments to the Act, Congress restricted the use of tall smokestacks as a means to attain compliance in SIPs.

Major and area sources of pollution

There are four main types of air pollution sources: mobile, stationary, area, and natural sources. Mobile sources, which include cars, buses, planes, trucks, and trains, are responsible for more than half of the air pollution in the United States, with automobiles being the primary contributor. Stationary sources, on the other hand, emit large amounts of pollution from a single location, such as power plants, oil refineries, industrial facilities, and factories. These are also known as point sources of pollution.

Major sources of pollution, as defined by the Clean Air Act (CAA), are stationary sources or groups of stationary sources that emit or have the potential to emit 10 tons per year or more of a hazardous air pollutant, or 25 tons per year or more of a combination of such pollutants. The CAA requires these major sources to install pollution control equipment, meet specific emissions limitations, and obtain operating permits. Examples of major sources include power plants, refineries, boilers, and factories.

Area sources, the third type, are smaller pollution sources that collectively have a significant impact. These include agricultural areas, cities, residential wood burning, and wood-burning fireplaces. While each source may not contribute much, together they can emit almost half of the air pollution in certain regions, as is the case with Minnesota.

Lastly, natural sources of air pollution include wind-blown dust, wildfires, and volcanoes. While these are not always under human control, they can have significant impacts on air quality. For example, summertime wildfires can reduce visibility and create haze, affecting both protected natural areas and populated places.

EPA's Clean Air Markets Division (CAMD)

The Clean Air Act (CAA) is a comprehensive federal law that regulates air emissions from stationary and mobile sources. The Act authorises the US Environmental Protection Agency (EPA) to establish National Ambient Air Quality Standards (NAAQS) to protect public health and welfare and to regulate emissions of hazardous air pollutants.

The EPA's Clean Air Markets Division (CAMD) runs programs that reduce air pollution from power plants. These programs aim to address several environmental problems, including acid rain, ozone and particle pollution, and the interstate transport of air pollution.

The CAMD programs include the Acid Rain Program (ARP), the Cross-State Air Pollution Rule (CSAPR), and the Revised CSAPR Update. The Acid Rain Program, for example, was developed to address the environmental issues caused by acidic compounds in the atmosphere, which can have detrimental effects on aquatic ecosystems and infrastructure. The CAA requires major stationary sources, such as power plants, to install pollution control equipment and meet specific emissions limitations.

Additionally, the CAA sets limits on certain air pollutants, including carbon monoxide, ground-level ozone, lead, nitrogen oxides, particulate matter, and sulfur dioxide. The EPA is also responsible for regulating emissions of hazardous air pollutants from chemical plants, utilities, and steel mills. The Act was amended in 1977 and 1990 to set new goals and deadlines for achieving NAAQS, as many areas of the country had failed to meet the initial targets.

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