R E S O U R C E L I B R A R Y E N C Y C L O P E D I C E N T RY Air pollution

Air pollution consists of chemicals or particles in the air that can harm the health of humans, animals, and plants. It also damages buildings.

G R A D E S 4 - 12+

S U B J E C T S Biology, Ecology, Earth Science, Geography

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Air pollution consists of chemicals or particles in the air that can harm the health of humans, animals, and plants. It also damages buildings. Pollutants in the air take many forms. They can be gases, solid particles, or liquid droplets.

Sources of Air Pollution

Pollution enters the Earth's atmosphere in many different ways. Most air pollution is created by people, taking the form of emissions from factories, cars, planes, or aerosol cans. Second- hand cigarette smoke is also considered air pollution. These man-made sources of pollution are called anthropogenic sources. Some types of air pollution, such as smoke from wildfires or ash from volcanoes, occur naturally. These are called natural sources.

Air pollution is most common in large cities where emissions from many different sources are concentrated. Sometimes, mountains or tall buildings prevent air pollution from spreading out. This air pollution often appears as a cloud making the air murky. It is called smog. The word "smog" comes from combining the words "smoke" and "fog."

Large cities in poor and developing nations tend to have more air pollution than cities in developed nations. According to the World Health Organization (WHO), some of the worlds most polluted cities are Karachi, Pakistan; New Delhi, India; Beijing, China; Lima, Peru; and Cairo, Egypt. However, many developed nations also have air pollution problems. Los Angeles, California, is nicknamed Smog City.

Indoor Air Pollution

Air pollution is usually thought of as smoke from large factories or exhaust from vehicles. But there are many types of indoor air pollution as well.

Heating a house by burning substances such as kerosene, wood, and coal can contaminate the air inside the house. Ash and smoke make breathing difficult, and they can stick to walls, food, and clothing.

Naturally-occurring radon gas, a cancer-causing material, can also build up in homes. Radon is released through the surface of the Earth. Inexpensive systems installed by professionals can reduce radon levels.

Some construction materials, including insulation, are also dangerous to people's health. In addition, ventilation, or air movement, in homes and rooms can lead to the spread of toxic mold. A single colony of mold may exist in a damp, cool place in a house, such as between walls. The mold's spores enter the air and spread throughout the house. People can become sick from breathing in the spores.

Effects On Humans

People experience a wide range of health effects from being exposed to air pollution. Effects can be broken down into short-term effects and long-term effects. Short-term effects, which are temporary, include illnesses such as pneumonia or bronchitis. They also include discomfort such as irritation to the nose, throat, eyes, or skin. Air pollution can also cause headaches, dizziness, and nausea. Bad smells made by factories, garbage, or sewer systems are considered air pollution, too. These odors are less serious but still unpleasant.

Long-term effects of air pollution can last for years or for an entire lifetime. They can even lead to a person's death. Long-term health effects from air pollution include heart disease, lung cancer, and respiratory diseases such as emphysema. Air pollution can also cause long- term damage to people's nerves, brain, kidneys, liver, and other organs. Some scientists suspect air pollutants cause birth defects. Nearly 2.5 million people die worldwide each year from the effects of outdoor or indoor air pollution.

People react differently to different types of air pollution. Young children and older adults, whose immune systems tend to be weaker, are often more sensitive to pollution. Conditions such as asthma, heart disease, and lung disease can be made worse by exposure to air pollution. The length of exposure and amount and type of pollutants are also factors.

Effects On The Environment

Like people, animals, and plants, entire ecosystems can suffer effects from air pollution. Haze, like smog, is a visible type of air pollution that obscures shapes and colors. Hazy air pollution can even muffle sounds.

Air pollution particles eventually fall back to Earth. Air pollution can directly contaminate the surface of bodies of water and soil. This can kill crops or reduce their yield. It can kill young trees and other plants.

Sulfur dioxide and nitrogen oxide particles in the air, can create acid rain when they mix with water and oxygen in the atmosphere. These air pollutants come mostly from coal-fired power plants and motor vehicles. When acid rain falls to Earth, it damages plants by changing soil composition; degrades water quality in rivers, lakes and streams; damages crops; and can cause buildings and monuments to decay.

Like humans, animals can suffer health effects from exposure to air pollution. Birth defects, diseases, and lower reproductive rates have all been attributed to air pollution. Global Warming

Global warming is an environmental phenomenon caused by natural and anthropogenic air pollution. It refers to rising air and ocean temperatures around the world. This temperature rise is at least partially caused by an increase in the amount of greenhouse gases in the atmosphere. Greenhouse gases trap heat energy in the Earths atmosphere. (Usually, more of Earths heat escapes into space.)

Carbon dioxide is a greenhouse gas that has had the biggest effect on global warming. Carbon dioxide is emitted into the atmosphere by burning fossil fuels (coal, gasoline, and natural gas). Humans have come to rely on fossil fuels to power cars and planes, heat homes, and run factories. Doing these things pollutes the air with carbon dioxide.

Other greenhouse gases emitted by natural and artificial sources also include methane, nitrous oxide, and fluorinated gases. Methane is a major emission from coal plants and agricultural processes. Nitrous oxide is a common emission from industrial factories, agriculture, and the burning of fossil fuels in cars. Fluorinated gases, such as hydrofluorocarbons, are emitted by industry. Fluorinated gases are often used instead of gases such as chlorofluorocarbons (CFCs). CFCs have been outlawed in many places because they deplete the ozone layer.

Worldwide, many countries have taken steps to reduce or limit greenhouse gas emissions to combat global warming. The Kyoto Protocol, first adopted in Kyoto, Japan, in 1997, is an agreement between 183 countries that they will work to reduce their carbon dioxide emissions. The United States has not signed that treaty.

Regulation

In addition to the international Kyoto Protocol, most developed nations have adopted laws to regulate emissions and reduce air pollution. In the United States, debate is under way about a system called cap and trade to limit emissions. This system would cap, or place a limit, on the amount of pollution a company is allowed. Companies that exceeded their cap would have to pay. Companies that polluted less than their cap could trade or sell their remaining pollution allowance to other companies. Cap and trade would essentially pay companies to limit pollution.

In 2006 the World Health Organization issued new Air Quality Guidelines. The WHOs guidelines are tougher than most individual countries existing guidelines. The WHO guidelines aim to reduce air pollution-related deaths by 15 percent a year.

Reduction

Anybody can take steps to reduce air pollution. Millions of people every day make simple changes in their lives to do this. Taking public transportation instead of driving a car, or riding a bike instead of traveling in carbon dioxide-emitting vehicles are a couple of ways to reduce air pollution. Avoiding aerosol cans, recycling yard trimmings instead of burning them, and not smoking cigarettes are others. Vocabulary

Part of Term Definition Speech precipitation with high levels of nitric and sulfuric acids. Acid rain acid rain noun can be manmade or occur naturally. container of liquid material under high pressure. When released aerosol can noun through a small opening, the liquid becomes a spray or foam. air pollution noun harmful chemicals in the atmosphere. anthropogenic noun caused by people. source asthma noun disease that makes it difficult to breathe. atmosphere noun layers of gases surrounding a planet or other celestial body. attribute verb to think to be caused by. birth defect noun physical disorder present at birth and not developed later. bronchitis noun irritation of the main air passages to the lungs. cancer noun growth of abnormal cells in the body. system for reducing air pollution by placing limits on how much cap and trade noun companies can pollute without having to pay for it. greenhouse gas produced by animals during respiration and used carbon dioxide noun by plants during photosynthesis. Carbon dioxide is also the byproduct of burning fossil fuels. chemical noun molecular properties of a substance. chemical compound mostly used in refrigerants and flame- chlorofluorocarbon noun retardants. Some CFCs have destructive effects on the ozone (CFC) layer. cigarette noun thin roll of tobacco for smoking. Part of Term Definition Speech coal noun dark, solid fossil fuel mined from the earth. coal-fired power noun power plant that makes electricity by burning coal. plant colony noun network of mold cells considered as one organism. combat verb to fight. concentrated adjectiveitems gathered closely together in one place. consider verb to think about. contaminate verb to poison or make hazardous. crop noun agricultural produce. current noun steady, predictable flow of fluid within a larger body of that fluid. decade noun 10 years. decay verb to rot or decompose. degrade verb to lower the quality of something. a nation that has high levels of economic activity, health care, and developed countrynoun education. nations with low per-capita income, little infrastructure, and a developing world noun small middle class. downwind adjectivein the direction of the wind. person who was accidentally exposed to radioactive particles downwinder noun from the Nevada Test Site. community and interactions of living and nonliving things in an ecosystem noun area. emission noun discharge or release. emit verb to give off or send out. emphysema noun disease of the lungs. exceed verb to go beyond the limit. exhaust noun gases and particles expelled from an engine. factory noun one or more buildings used for the manufacture of a product. fluorinate verb to add or combine with the element fluorine (F). fog noun clouds at ground level. coal, oil, or natural gas. Fossil fuels formed from the remains of fossil fuel noun ancient plants and animals. garbage noun trash or waste material. state of matter with no fixed shape that will fill any container gas noun uniformly. Gas molecules are in constant, random motion. Part of Term Definition Speech gasoline noun liquid mixture made from oil and used to run many motor vehicles. global warming noun increase in the average temperature of the Earth's air and oceans. gas in the atmosphere, such as carbon dioxide, methane, water greenhouse gas noun vapor, and ozone, that absorbs solar heat reflected by the surface of the Earth, warming the atmosphere. group of solid and liquid particles in the air that makes it difficult haze noun to see. heart disease noun illness affecting the heart and circulatory system. hydrofluorocarbon noun greenhouse gas often used as an industrial cooling material. illness noun disease or sickness. network of chemicals and organs that protects the body from immune system noun disease. incident noun event or happening. indoor air pollutionnoun harmful chemicals coming from or accumulating inside a building. insulation noun material used to keep an object warm. irritation noun condition of unpleasant sensitivity. kerosene noun flammable liquid used as fuel. organ that removes the waste products from blood and helps kidney noun regulate general health. (1997) international agreement to reduce greenhouse gas Kyoto Protocol noun emissions. state of matter with no fixed shape and molecules that remain liquid noun loosely bound with each other. organ that removes toxins from the blood, converts sugar to liver noun glycogen, and produces bile needed for digestion. (December 5December 9, 1952) severe smog that killed between London Fog of noun 4,000 and 12,000 people in London, England. Also called the 1952 Great Smog. long-term effects noun results of an incident or behavior that last for years or a lifetime. lung noun organ in an animal that is necessary for breathing. man-made noun produced by people. methane noun chemical compound that is the basic ingredient of natural gas. mold noun type of fungi that forms on the surface of materials. motor vehicle noun method of transportation that is run by an electric or gas engine. mountain noun landmass that forms as tectonic plates interact with each other. Part of Term Definition Speech natural gas noun type of fossil fuel made up mostly of the gas methane. natural source noun caused by nature or the environment. nausea noun impulse to vomit. nerve noun part of the nervous system that registers sensation and touch. testing site for nuclear weapons and other military products in Nevada Test Site noun the southern Nevada desert. Nuclear weapons testing was discontinued there in 1992. one of many chemical compounds made of different nitrogen oxide noun combinations of nitrogen and oxygen. greenhouse gas used in medicine and the manufacture of rockets. nitrous oxide noun Also known as laughing gas or happy gas. explosive device that draws power from the splitting and nuclear weapon noun combining of atomic nuclei. obscure verb to darken or partially block. odor noun smell. chemical element with the symbol O, whose gas form is 21% of the oxygen noun Earth's atmosphere. layer in the atmosphere containing the gas ozone, which absorbs ozone layer noun most of the sun's ultraviolet radiation. particle noun small piece of material. phenomenon noun an unusual act or occurrence. pneumonia noun infection where lungs fill with fluid. pollutant noun chemical or other substance that harms a natural resource. methods of movement that are available to all community public noun members for a fee, and which follow a fixed route and schedule: transportation buses, subways, trains and ferries. Radiation (1990) law providing money to people who developed cancer as a Exposure noun result of exposure to radiation in the atmosphere near nuclear Compensation Act test sites. atom or part of an atom with excess energy that decays and radioactive particlenoun changes the properties of the atom. Also called a hot particle. radon noun chemical element with the symbol Rn. recycle verb to clean or process in order to make suitable for reuse. reduce verb to lower or lessen. regulate verb to determine and administer a set of rules for an activity. Part of Term Definition Speech rely verb to depend on. number of live offspring produced by a single female per reproductive rate noun reproductive cycle, usually a year. respiratory disease noun illness having to do with the lungs and breathing. sewer system noun network of drains disposing liquid and solid waste. results of an incident or behavior that last days or months and do short-term effect noun not return. type of air pollution common in manufacturing areas or areas with smog noun high traffic. smoke noun gases given off by a burning substance. soil noun top layer of the Earth's surface where plants can grow. material, including chemicals, air, and moisture, that make up a soil composition noun section of earth. state of matter with a fixed shape and molecules that vibrate but solid noun do not move. spore noun reproductive unit of some organisms. sulfur dioxide noun greenhouse gas that can cause acid rain. degree of hotness or coldness measured by a thermometer with a temperature noun numerical scale. temporary adjectivenot lasting or permanent. airborne particles released by mold (not the mold itself) that can toxic mold noun cause health problems for people and animals. treaty noun official agreement between groups of people. unpleasant adjectiveoffensive or foul. movement or circulation of fresh air in a closed environment. Also ventilation noun called air circulation. volcanic ash noun fragments of lava less than 2 millimeters across. an opening in the Earth's crust, through which lava, ash, and volcano noun gases erupt, and also the cone built by eruptions. uncontrolled fire that happens in a rural or sparsely populated wildfire noun area. World Health Organization noun United Nations agency responsible for health. (WHO) yard noun land surrounding a house or building. Part of Term Definition Speech grass, leaves, and small branches left over from mowing and yard trimmings noun cutting back local vegetation. Also called yard waste. yield verb to produce or result in. Maps AIRNow: Tracking Ozone and Particle Pollution

Websites Environmental Protection Agency: Indoor Air Pollution—Volatile Organic Compounds National Geographic Environment: Air Pollution National Geographic Environment: Global Warming EPA: Air and Radiation

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