1. Cleaning up Commonly Found Air Pollutants

The six common air pollutants of primary concern to the United States are particle pollution, ground-level ozone, carbon monoxide, sulfur oxides, nitrogen oxides, and lead.^[1] These pollutants are detrimental to health, the environment, and a person's home and other belongings. The worst two of the six pollutants are particle pollution and ground-level ozone, which have to be regulated by the EPA. Particle pollution, or particle matter, consists of soot, smoke, and chemically formed "droplets".^[1] These particles are very small and can bury themselves deep inside the lungs. Ground-level ozone is found in smog and can also negatively affect the lungs. Smog contains volatile organic compounds (VOCs) and nitrogen oxides (NOx). VOCs come from cars burning gasoline, petroleum refineries, chemical manufacturing plants, etc., while NOx results from burning gasoline, coal, or oil.^[1]

2. Cars, Trucks, Buses, and Non-road Equipment

Motor vehicles contribute a great deal to air pollution, so to reduce the amount of emissions released, the EPA placed restrictions on fuel and engine production. As a result, manufacturers are required to build cleaner engines and refiners are required to produce cleaner fuels. Gasoline used to include lead, which can cause damage to bodily functions and organs and sulfur was lowered over 90 percent in fuels because it doesn't allow a vehicle's catalytic converter to effectively clean up the exhaust.^[2] Unlike most small cars, the majority of trucks, buses, and non-road equipment use diesel engines because they are more fuel efficient. However, they are also more harmful to the environment. In order to cut the emissions, the EPA issued rules to combine strict emissions standards for diesel engines and to lower sulfur diesel fuel.^[2]

Alternative fuels such as natural gas, propane, methanol, ethanol, electricity, and biodiesel, are a major area of interest for the Clean Air Act. It is also important to find renewable fuels that can come from resources such as wood, waste paper, grasses, vegetable oils, and corn.^[2]

3. Interstate and International Air Pollution

Air pollution is not contained and is carried by the wind all over the world. Industries contribute air pollution in the form of smog and haze in "downwind states".^[3] Sometimes pollution from "upwind states" blows into the downwind states, which can affect their air quality standards. These states can ask the EPA to enforce "a federal plan" to make sure that the standards are met. The Clean Air Act also requires that national parks maintain clear air; therefore, the EPA must collaborate with states to diminish the "regional haze" in national parks and wilderness areas.^[3]

4. Reducing Acid Rain

Acid precipitation comes in more forms than just rain. Snow, fog, mist, gas, and dust are also formed in the atmosphere and have the ability to become acid precipitation.^[4] These types of precipitation are formed when certain types of air pollutants mix with the moisture in the air to form an acid. Each type is potentially dangerous to humans' health, can cause haze and problems in the environment, and can cause damage to people's properties. The two main pollutants that cause acid precipitation are sulfur dioxide (SO2) and nitrogen oxides (NOx). Power plants that burn coal and "heavy oil" are accountable for over two-thirds of SO2 emissions annually in the U.S., while automobiles emit about fifty percent NOx and power plants emit about forty percent. The remaining percentages are from industrial and commercial boilers.^[4]

Any toxin is harmful to life on Earth. Acid rain and snow can increase the acidity in lakes and streams long enough to harm fish and other forms of life. Sulfur dioxide can be dangerous to children and the elderly by causing serious damage to lung tissue. In 1990, the Clean Air Act was changed to include a "nationwide approach" to lowering SO2 and NOx emissions. A cap was placed on the total SO2 emissions from electric power plants across the U.S.^[4]

5. Reducing Toxic Air Pollutants

Toxic air pollutants are the suspected cause of major illnesses and issues with reproductive problems. These pollutants stay in the environment for long periods, which can affect all living things and start a chain of negative events. In particular, smokestacks and automobiles are the two main sources of toxic air pollutants. When refueling, the gases turn into vapor that leak into the air. "Before the 1990 Clean Air Act Amendments, EPA regulated air toxics one chemical at a time." ^[5] The EPA now regulates pollutants by categories of industries because they release more than one chemical at a time. Some of the categories are, chemical plants, incinerators, dry cleaners, and manufacturers of wood furniture. Since the 1990 Clean Air Act, air toxics from large industries have already been reduced by 70 percent.^[5]

6. Protecting the Stratosphere Ozone Layer

Ozone can be harmful if it is ground-level, but if it is in the stratosphere, it protects the Earth from ultraviolet rays from the sun. The stratosphere blocks some of the light called ultraviolet B, which can cause skin cancer and eye damage. It can also damage plant life on land and in the ocean.^[6] Some of the main pollutants that are harmful to the stratosphere are called chlorofluorocarbons (CFCs). They come from aerosols such as hairspray, air conditioners, and some other types. They were banned in the 1970s. In the 1980s, scientists found that there were holes in the ozone around the South Pole. As a result, over 190 countries, including the United States, signed the 1987 Montreal Protocol. This agreement is designated to eliminating chemicals that harm the stratosphere.^[6] The 1990 Clean Air Act "phased out" the most harmful chemicals and in 1996, production of CFCs, halons, and methyl chloroform ended in the United States. There are still holes in the ozone that will take approximately 60 years to close up because of the chemicals that are already in the stratosphere.^[6]

7. Permits and Enforcement

Congress added an operating permit program to the 1990 Clean Air Act for larger industries and commercial sources that release toxins into the air.^[7] These permits have information about which pollutants are emitted, how much may be emitted, and what actions the person in charge is taking to minimize the pollution. Permits must also state plans to measure and report the air pollution produced. The EPA is also responsible for making sure each state and tribe abides by the permits.^[7] For businesses that qualify for more than one thing under the Clean Air Act, operating permits are helpful because the information is all there. These permits tell them exactly what they need to do to prevent pollution. Now the EPA is more powerful in being able to enforce the rules instead of having to handle everything in court. The EPA can either "issue an order requiring the violator to comply, issue and administrative penalty order, or bring a civil judicial action".^[7]

8. Public Participation

Since the 1990 Clean Air Act, the public has the opportunity to give input on "how a law is carried out".^[8] Hearings are held in different cities in the United States by the EPA. Anyone who attends is allowed to participate or written comments can be sent to the EPA. These hearings are open to the public when a "major rule" is about to be discussed.^[8] The more public input is recorded, the better the outcome will be for communities around the country. Reports from the Clean Air Act are made available to the public and they include information about the amount of pollution that is emitted by industries and other sources.^[8]