Teacher Fact Sheet
Chapter 2: Air Pollution
Air is never absolutely pollution-free. Small suspended solids and liquids from sources such as dust, forest fires, volcanic activity, and salt from the oceans are constantly moving around in the atmosphere. In fact, these minute particles are important for cloud formation. As moist air cools, water droplets begin collecting on particulate matter, building clouds. The more particles and water vapor, the more clouds that are formed. Precipitation cleanses the air of particulates, which is why the air is cleaner and clearer after a rainstorm.
However, human activities add significant amounts of pollutants to the atmosphere, often exceeding the ability of natural processes to eliminate them. Air pollution comes from many different sources. These include stationary sources such as factories, power plants, and smelters; smaller sources such as dry cleaners and degreasing operations; mobile sources such as cars, buses, planes, trucks, and trains; and natural sources such as windblown dust, wildfires and biogenic emissions—those released by vegetation such as trees.
More people in cities and surrounding counties means more cars, trucks, industrial and commercial operations, and generally, more pollution. Even before Tulsa’s first oil boom, in 1901, Tulsans experienced air pollution. Coal mining, farming, and day-to-day activities contributed to pollution formation. As the Tulsa area grew economically, so did its air pollution issues.
Ever since humans discovered how to
make fire, they have been adding pollutants to the air. Once humans
began to form permanent cities and towns, air quality began to be a
concern. In 61 A.D., Seneca, a philosopher in ancient Rome, noticed his
health was better when he left Rome and was away from the soot and steam
producing kitchens. At first, the most popular fuel used was wood or
peat.
But these fuel sources took a lot of time and energy to gather and were
not very efficient at heating. By the late 1700’s, coal began to be the
fuel of choice and was a major factor in the Industrial Revolution, but
it is very dirty. 
Smog, a combination of smoke and fog, was common in big cities, especially London and Los Angeles, CA, where coal was widely used. Severe smog episodes caused many deaths into the first half of the 20th century. People began to look for cleaner sources of energy. In the early 20th century, oil began to replace coal in many areas and allowed the wide-spread use of the automobile.
In 1955 the U.S. government recognized that air pollution was a national problem and enacted the Air Pollution Control Act, the first federal legislation dealing with the problem. Its main purpose was to provide money to the Public Health Service to research air pollution but actually did little to prevent it. Amendments in 1960 and 1962 extended funding and called for additional research by the Surgeon General into the health aspects of air pollution.
The Clean Air Act (CAA) of 1963 was the first U.S. attempt to control air pollution and for the first time recognized pollution hazards from mobile source (cars, trucks, etc) emissions as well as stationary sources(industry, fireplaces, etc.).
By 1970 the environmental movement was in full force, pressuring the government to better regulate and control pollution. They responded with a complete rewrite of the CAA. The new CAA set National Ambient Air Quality Standards (NAAQS), strictly regulated new emissions sources and set standards for hazardous emissions, including those from motor vehicles. The Act also allowed the public to take legal action against any polluter, including the federal government. Overseeing environmental standards of the air, land, and water was the newly formed Environmental Protection Agency (EPA). The EPA was tasked with setting and enforcing environmental policies and standards and conducting environmental research.
Although the EPA was established to carry out the requirements of the CAA, it is the states that have the major burden of enacting and enforcing EPA’s regulations. State and local governments know much more about local conditions, from weather patterns to individual industries, which makes the states better able to monitor air quality programs. In addition, states may pass their own air quality standards which can be stricter than the Federal government’s, but not weaker. States are required to develop State Implementation Plans (SIPs) that tell the EPA what they plan on doing to meet the regulations. SIPs and other agreements with the EPA keep air quality matters under the control of the states rather than the Federal government.
The average person breathes 3,000 gallons of air each day. Many air pollutants, such as those that form smog and toxic compounds, remain in the environment for long periods of time and are carried by the wind hundreds of miles from their origin. Millions of people live in areas where smog, very small particles, and toxic pollutants pose serious health concerns. Children are at greater risk to the effects of air pollution, because they are generally more active outdoors, and their lungs are still developing.Exposure to air pollution is associated with numerous effects on human health, including respiratory problems, hospitalization for heart or lung diseases, and even premature death.
Even when air pollution is invisible, it can be felt. Burning eyes, sore throats and difficulty breathing are some of the physical symptoms of air pollution. For a healthy person, this can be annoying. But for someone who already has health problems, such as asthma, pollution can make them much worse. Even healthy people exposed to pollutants over a long time can begin to have health problems. Trees and other plants can have trouble growing. Some forms of pollution produce rain that is acidic like vinegar which can wear away building material and harm lakes and ponds.
Air pollution can be divided into two broad categories. Primary pollutants are emitted directly into the atmosphere. Secondary pollutants are formed by chemical reactions from atmosphere emissions that may not be hazardous until they come into contact with each other.
The EPA has identified six criteria pollutants: particulates, carbon monoxide, nitrogen dioxide, sulfur dioxide, lead, and ozone. EPA has determined and set national standards (NAAQS) for these pollutants.
Particulates
When particles are present in large amounts, they form a visible haze. Sometimes the haze can barely be seen; other times the haze acts more like a thick fog, blocking out distant features such as mountains. As particulates settle, they can change the chemistry of soil and water, and stain and damage buildings. Haze is not confined to large cities. It is a problem in places such as the Grand Canyon. Wind also carries particulates away from their source, affecting areas many miles away.
People constantly breathe particulates, and lungs are well-equipped to handle most of them. Little hairs called cilia, that line throats and lungs, help sweep small particles away. But when particulates are high, they can stick in the airways and cause coughing and difficulty breathing. Respiratory problems such as asthma or bronchitis can be made worse by the irritation. Some very sensitive people can be seriously affected by particulates and may need to seek medical treatment.
Carbon Monoxide
Carbon monoxide is a colorless, odorless gas that can be very dangerous in high amounts. Most carbon monoxide comes from car and truck exhaust. Other sources are factories, fireplaces, and outdoor grills. When breathed, carbon monoxide goes into the lungs and then travels into the bloodstream. It replaces the oxygen that is carried on the red blood cells, and in high enough concentrations, it can be deadly. At low levels, healthy people may get headaches or feel lightheaded. People with heart disease may develop chest pains and have trouble breathing.
Nitrogen Oxides
While nitrogen dioxide is a criteria pollutant, nitrogen oxides refer to many different chemicals that are made of oxygen and nitrogen. Most are odorless and colorless, although some nitrogen particles are visible as a reddish-brown haze.
Nitrogen oxides are formed from burning fuels plants, factories and other industrial processes.
All nitrogen oxides are reactive. They may combine with other compounds such as volatile organic compounds (VOCs) to form ground-level ozone. Nitrogen oxides also react with other chemicals to form acid rain or other harmful chemicals. In addition, nitrogen oxide is a greenhouse gas and is thought to be a factor in global warming.
Sulfur Dioxide
When coal is burned to create electricity, when gasoline is refined from crude oil, or when metals are extracted from ore, sulfur oxides are released. Sulfur dioxide easily dissolves in water, making it acidic. It also reacts with other chemicals and particles to form sulfates. Sulfur dioxide is irritating to the lungs and throat and can be very dangerous to children and those who have heart and lung diseases or asthma.
Sulfur dioxide is easily transported through the air, traveling many miles away from its source. It returns to the Earth as acid rain, which damages buildings, plants, and bodies of water. It is also a component of haze in many big cities.
Lead
At one time, gasoline was the major source of lead in the atmosphere. Today, leaded gasoline has been completely banned in the United States, and the major sources of lead are from lead smelters, lead acid battery manufacturers, and waste combustion. As a result, lead in the environment has declined drastically.
Lead is particularly harmful to children. It damages organs such as the kidneys and liver and affects the brain. It can also cause high blood pressure and heart disease. Animals and fish exposed to lead can have health problems. People can have increased lead levels if they eat a lot of contaminated fish and shellfish.
Ozone and VOCs
High up in the stratosphere, a form of oxygen known as ozone protects life on Earth from the sun’s harmful radiation. But close to the ground, ozone is a secondary pollutant. It is formed when nitrogen oxides react with VOCs in the presence of sunlight and heat. Although it is often considered a summertime pollutant, under the right conditions ground-level ozone can form in the winter. Ozone can be carried in the air and affect towns and rural areas miles away from a city.
Ozone irritates lungs and airways, aggravating health problems such as asthma. Airways even in healthy people can become red and swollen, causing sore throats, chest pains, and shortness of breath. It also damages plants, costing farmers millions of dollars in lost crops.
Chemically, stratospheric ozone is the same as ground level ozone, but it is formed in a different way. When ultraviolet radiation from the sun hits oxygen molecules with two oxygen atoms, it splits them. The atoms then can recombine in a group of three oxygen atoms, forming ozone. This process constantly breaks down and reforms as ozone and, at the same time, blocks most of the harmful radiation from striking the Earth.
But stratospheric ozone has been affected by air pollution. In the 1970’s, scientists noticed the ozone layer was thinning, creating an area that resembled a hole. Research has shown that compounds called chlorofluorocarbons (CFCs) and some other nitrogen compounds are responsible for the thinning in the ozone layer. Human products like those used in air conditioners, refrigerators, insulation, and spray cans are the culprit. When they are released into the atmosphere, they travel into the stratosphere where they are broken down by sunlight and ozone thinning occurs.
Weather is an important factor in how bad pollution is on any given day. Wind and unstable air mixes polluted air with cleaner air. Winds carry pollutants away from their sources, and can spread it for miles. Rain washes particulates out of the air and deposits them on the ground, often cleansing the air, but can also cause problems for soil, water, and plants.
Air pollution is worse during hot days with little or no wind. Sometimes, pollutant-trapping temperature inversions may occur. Inversions are natural weather events that trap warmer air next to the earth with a blanket of colder, heavier air. When the lower air can’t carry away the pollutants because of this blanket effect, serious air quality problems for the immediate area can result. In a typical metro area, like Tulsa more pollutants are emitted into the air as traffic increases during the day. When the day is hot, sunny and with minimal wind, unhealthy levels of ozone can form.