Air Pollutants: Epa's Six Criteria For Clean Air

The Clean Air Act requires the US Environmental Protection Agency (EPA) to set National Ambient Air Quality Standards (NAAQS) for six common air pollutants, known as criteria air pollutants. These pollutants are found all over the United States and can harm human health, the environment, and cause property damage. The six criteria air pollutants are particle pollution, ground-level ozone, carbon monoxide, sulfur dioxide, nitrogen dioxide, and lead. The EPA tracks air concentrations through measurements at monitoring sites and emissions through engineering estimates of total tons released into the air annually.

Particle pollution and ground-level ozone are the most widespread health threats

The Clean Air Act requires the Environmental Protection Agency (EPA) to set National Ambient Air Quality Standards for six common air pollutants. These pollutants, also known as "criteria air pollutants", are particle pollution, ground-level ozone, carbon monoxide, sulfur dioxide, nitrogen dioxide, and lead. Of these six pollutants, particle pollution and ground-level ozone are the most widespread health threats.

Particle pollution, or particulate matter, is a mixture of extremely small particles and liquid droplets in the air. These particles enter the air from a variety of sources and may be either directly emitted or formed through a chemical process. Many particles enter the air directly from power plants, factories, automobiles, construction vehicles, unpaved roads, wood burning, and agricultural sites. Others are formed through a reaction between gases from burning fuels, sunlight, and water vapour. High levels of particles in the air can affect the lungs and heart and have been shown to trigger asthma and heart attacks, among other health issues.

Ground-level ozone is not emitted directly into the air but is created by chemical reactions between oxides of nitrogen and volatile organic compounds in the presence of sunlight and heat. Air pollutants from car exhaust, paint, aerosol products, and manufacturing emissions are some of the major contributors to ground-level ozone. Ground-level ozone is a harmful air pollutant because of its effects on human health and the environment, and it is the main ingredient in "smog". Ozone in the air can reduce lung function by up to 20% and can trigger adverse health reactions in children, older adults, and those with respiratory or pulmonary conditions.

To address these health threats, the EPA designates areas as attainment or nonattainment based on air quality standards. States with nonattainment areas must draft a plan to improve air quality and meet the EPA's national air quality standards. These regulations help states reduce particle pollution and ground-level ozone levels in outdoor air.

Carbon monoxide is linked to coughing and wheezing

The Clean Air Act requires the United States Environmental Protection Agency (EPA) to set National Ambient Air Quality Standards for six common air pollutants: particle pollution, ground-level ozone, carbon monoxide, sulfur dioxide, nitrogen dioxide, and lead. These pollutants are harmful to human health, the environment, and property.

Carbon monoxide (CO) is a colorless, odorless, and tasteless gas produced when gasoline, coal, wood, and other fuels burn. It can build up quickly and is dangerous at high levels. CO fumes can form from car and truck engines, fuel-burning space heaters, gas stoves, home furnaces, and charcoal, kerosene, or wood-burning.

Carbon monoxide poisoning is a life-threatening complication of inhaling carbon monoxide fumes. It prevents the body from using oxygen correctly, which can harm the brain, heart, and other organs. People with existing health problems, such as heart and lung disease, are at greater risk of harm, as are infants, children, pregnant people, and older adults. Symptoms of carbon monoxide poisoning include headache, dizziness, nausea, vomiting, shortness of breath, chest pain, and disorientation. While coughing and wheezing were not explicitly mentioned as symptoms of carbon monoxide poisoning in the sources I found, shortness of breath was, and coughing and wheezing can be related to respiratory distress.

It is important to prevent carbon monoxide poisoning by installing CO detectors, assuring that fireplaces and heaters are working correctly, and properly ventilating areas where fuel is burned. If carbon monoxide poisoning is suspected, it is crucial to act quickly: turn off the CO source if possible, get fresh air immediately, and call emergency services.

Lead can cause neurodevelopmental issues

The Clean Air Act requires the US Environmental Protection Agency (EPA) to set National Ambient Air Quality Standards for six common air pollutants, also known as "criteria air pollutants". These pollutants are particle pollution, ground-level ozone, carbon monoxide, sulfur dioxide, nitrogen dioxide, and lead. These pollutants are harmful to human health, the environment, and can cause property damage.

Lead is a naturally occurring toxic metal found in the Earth’s crust. Its widespread use has caused extensive environmental contamination, human exposure, and significant public health problems globally. Lead was once used in paint and gasoline and is still used in batteries, solder, pipes, pottery, roofing materials, and some cosmetics. Lead-based paints for homes, children's toys, and household furniture have been banned in the United States since 1978. However, lead-based paint still exists in many older homes and apartments.

In particular, lead can permanently affect children’s brain development, resulting in reduced intelligence quotient (IQ), behavioural changes including reduced attention span and increased antisocial behaviour, and reduced educational attainment. Lead exposure can also cause anaemia, hypertension, renal impairment, immunotoxicity, and toxicity to the reproductive organs. There is no known safe blood lead concentration; even blood lead concentrations as low as 3.5 µg/dL may be associated with decreased intelligence in children, behavioural difficulties, and learning problems.

Nitrogen dioxide and sulfur dioxide are harmful to health and the environment

Nitrogen dioxide (NO2) and sulfur dioxide (SO2) are two of the six criteria air pollutants outlined by the EPA. These pollutants are harmful to both human health and the environment. Nitrogen dioxide is one of a group of highly reactive gases known as nitrogen oxides (NOx). It primarily enters the air through the burning of fuel, with cars, trucks, buses, and power plants being the main sources of emissions. Breathing air with high NO2 concentrations can irritate the airways and aggravate respiratory diseases, especially asthma. Prolonged exposure may even contribute to the development of asthma. NO2 also reacts with other chemicals in the air to form particulate matter and ozone, both of which are harmful when inhaled. Additionally, NOx contributes to the formation of acid rain, which damages sensitive ecosystems such as lakes and forests.

Sulfur dioxide, another criteria air pollutant, is a gaseous air pollutant composed of sulfur and oxygen. It is formed when sulfur-containing fuels like coal, petroleum oil, or diesel are burned. Power plants, boilers, internal combustion engines, and industrial processes are significant sources of SO2 emissions. Sulfur dioxide can cause a range of adverse effects on the lungs, including wheezing, shortness of breath, and chest tightness. It can also chemically transform into sulfate particles, contributing to fine particle pollution, which can be blown over long distances.

People living or working near major sources of these pollutants, such as ports, smelters, or power plants, are at the highest risk of exposure. However, emissions of both nitrogen dioxide and sulfur dioxide have decreased over time due to policies promoting cleaner fuels and pollution controls on power plants. These efforts are crucial in mitigating the harmful impacts of these pollutants on human health and the environment.

The Clean Air Act mandates that the EPA establish National Ambient Air Quality Standards for these six common air pollutants, including nitrogen dioxide and sulfur dioxide. These pollutants have far-reaching health and environmental consequences and can also result in property damage. By setting science-based guidelines and standards, the EPA aims to protect human health and the environment from the detrimental effects of these harmful pollutants.

National Ambient Air Quality Standards are designed to protect welfare

The Clean Air Act requires the Environmental Protection Agency (EPA) to set National Ambient Air Quality Standards (NAAQS) for six principal pollutants, also known as "criteria air pollutants". These pollutants are particle pollution, ground-level ozone, carbon monoxide, sulfur dioxide, nitrogen dioxide, and lead. These pollutants are harmful to public health and the environment.

The NAAQS are designed to protect public welfare from the adverse effects of air pollution. They aim to prevent damage to soils, water, crops, vegetation, man-made materials, animals, wildlife, and property. The standards also address transportation hazards, economic values, and personal comfort and well-being.

The Clean Air Act identifies two types of NAAQS: primary and secondary standards. The primary standards focus on protecting public health, including sensitive populations such as asthmatics, children, and the elderly. These standards aim to prevent adverse health effects such as hospitalizations, emergency department visits, and premature death due to worsening heart and lung diseases. They also aim to reduce respiratory and asthma symptoms and medication usage.

The secondary standards focus on public welfare protection, including protection against decreased visibility and harm to animals, crops, vegetation, and buildings. These standards are designed to prevent environmental and property damage caused by air pollution. California, for example, has had ambient air quality standards since 1959, which predate the formation of the EPA and the adoption of the NAAQS.

To ensure the effectiveness of the NAAQS, the EPA periodically reviews and revises the standards based on scientific and technical information. This process involves tracking air pollution trends through measurements of pollutant concentrations and emissions estimates. The EPA's goal is to protect public health and welfare by setting and implementing guidelines for permissible levels of air pollutants.

Frequently asked questions