*What is Acid Rain?*
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acid deposition – acidic material that falls from the atmosphere to the earth in either wet (rain, sleet, snow, or fog) or dry (gases and particles) forms.

Acid Rain Program - a program run by the U.S. Environmental Protection Agency with the goal of reducing emissions of sulfur dioxide and nitrogen oxides. For more information see https://www.epa.gov/airmarkets/arp.

acidic – a term used to describe substances that have a value lower than 7 on the pH scale.

acidic pollutants - harmful particles, such as sulfur dioxide and nitrogen oxides, that turn into acid when they mix with water and oxygen in the sky.

alkaline – a term used to describe substances that have a value higher than 7 on the pH scale.

alkaline chemicals - substances that cause an object to become less acidic when they come into contact with each other.

allowance - the permission, given by the government, to emit a certain amount of sulfur dioxide or nitrogen oxides.

aluminum - a soft, lightweight metal that occurs naturally in the environment. Many things are made out of aluminum, including soda cans, automobile parts, and electrical equipment.

asthma - a physical condition that makes breathing difficult. People that have asthma usually experience a lot of wheezing and coughing, and often have difficulty doing physical exercise. Asthma is a condition
that people usually have for their entire lives.

basic – a term used interchangeably with alkaline.

bronchitis - a respiratory illness, similar to asthma, that makes breathing very difficult. Bronchitis is usually only a temporary illness.

cap - a national limit that is placed on the amount of a pollutant that can be emitted. This makes sure that the emissions of a pollutant are reduced.

compounds - mixtures containing 2 or more parts. Sulfur dioxide contains sulfur and oxygen, and nitrogen oxides contain nitrogen and oxygen.

ENERGY STAR® — a government-supported program helping businesses and individuals protect the environment through energy efficiency. Electronics and appliances—such as computers, refrigerators, washers, and air conditioners—carrying the ENERGY STAR label are guaranteed to be energy efficient. For more on this program, visit http://www.energystar.gov/.

episodic acidification - A short period of time when streams, lakes, and the ground have a much higher pH level then they normally do. This often happens in the spring, when the snow that contains acidic pollutants begins to melt.

exhaust - the combination of gases that is released from an automobile.

fossil fuels - substances found below the surface of the earth that can be burned to create energy. The three primary fossil fuels are coal, oil, and natural gas.

litmus paper - paper that indicates how acidic or basic an object or liquid is. If the paper turns red when touched by the object or liquid, it is acidic. If the paper turns blue, the object or liquid is basic.

neutralize - to make something less acidic.

ozone - a gas that is a form of oxygen. Ozone can be good if it is high in the atmosphere because it protects us from the harmful rays of the sun. Ozone is bad when it is close to the ground because it is a major air pollutant that can cause respiratory illnesses.

pH - a way of measuring the acidity of an object. Values of pH can range from 0-14, with 0 being the most acidic, and 14 being the least acidic. For more information on pH see Acid Rain and the pH Scale.

phytoplankton - a very small plant species that usually lives on the surface of bodies of water, such as lakes.

pneumonia - a very serious health condition where a person's lungs are filled with fluid. This makes it very hard for oxygen in the lungs to reach the blood stream.

precipitation - the collection of water molecules that falls from the sky as rain, sleet, hail, or snow.


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