The Air We Breathe
The air surrounding the Earth is made up of different gases: about 78% nitrogen, 21% oxygen, and 1% carbon dioxide, water vapor, and other gases. All human beings and animals need air to survive. Plants also need air. Plants use sunlight and the carbon dioxide in air to make food, and then give off oxygen.
|
|
|
World Almanac for Kids
|
|
This pie chart shows the makeup of the Earth's atmosphere
|
Humans breathe more than 3,000 gallons of air a day. Because air is so basic to life, it is important to keep it clean. Air pollution causes health problems and may bring about acid rain, smog, global warming, and a breakdown of the ozone layer.
Why worry about air pollution and acid rain?Air pollution and acid rain can harm people, animals, and plants. Air pollution can cause our eyes to sting and can even make some people sick. It can also damage crops and trees.
Air pollution is a dirtying of the air caused by toxic chemicals or other materials. It can injure health, the enjoyment of life, or the working of ecosystems. The major sources of air pollution are cars, trucks and buses, waste incinerators, factories, and some electric power plants, especially those that burn fossil fuels, such as coal.
Several New England states blame coal-burning power plants in the Midwest for polluting the air in the Northeast. The states say that the wind carries harmful emissions from Midwestern power plants eastward to the Northeast, causing breathing and other health problems. Northeasterners want tighter controls placed on the Midwestern plants, so they will give off fewer harmful pollutants. But Midwesterners argue that reducing emissions would require costly equipment, which they cannot afford.
What are we doing to reduce air pollution? Many countries are trying to reduce air pollution. In the United States, cars must have a special device to remove harmful chemicals from the exhaust before it comes out of the tailpipe. Many power plants and factories have devices on their smokestacks to catch chemicals. Many people try to use less electricity than they really need so that less coal will have to be burned to produce it. And in some places, power companies use windmills or other equipment that does not pollute the air.
|
|
|
World Almanac for Kids
|
|
Automobiles are one of the principal sources of air pollution.
|
Think about it! What are some of the sources of air pollution where you live? Think about what you and your friends could do to reduce it.
Acid rain is a kind of air pollution caused by chemicals in the air. Eventually these can make rain, snow, or fog more acidic than normal. The main sources of these chemicals are exhaust from cars, trucks, and buses, waste incinerators, factories, and some electric power plants, especially those that burn fossil fuels, such as coal. When these chemicals mix with moisture and other particles, they create sulfuric acid and nitric acid. The wind often carries these acids many miles before they fall to the ground in rain, snow, and fog, or even as dry particles.
Acid rain can harm people, animals, and plants. It is especially harmful to lakes. Thousands of lakes in Canada, Finland, Norway, and Sweden have been declared "dead." Not even algae can live in them. Birds and other species that depend on the lakes for food are also affected. Acid rain can also affect crops and trees. Buildings, statues, and cars can be damaged as it eats away metal, stone, and paint.
|
|
|
World Almanac for Kids
|
|
One of the places smog is created is at industrial plants that release pollutants into the air.
|
The brownish haze seen mostly in the summer and especially around big cities is smog. The main ingredient in smog is ozone. When ozone is high up in the atmosphere, it helps protect us from the Sun's stronger rays. But near the ground, ozone forms smog when sunlight and heat interact with oxygen and particles produced by the burning of fossil fuels. Smog makes it hard for some people to breathe, especially those with asthma. "Ozone Alerts" are not just for Los Angeles (famous for its smog). Many cities in the U.S. issue them through newspapers, TV, and radio stations to let people know when the air can be unhealthy for outdoor activities.
For more information visit .
Our atmosphere is made up of different layers. One layer, between 6 and 30 miles above the Earth, is made up of ozone gas. This ozone layer protects us from the Sun's harshest rays, called ultraviolet or UV rays. These rays can cause sunburn and skin cancer.
When refrigerators, air conditioners, and similar items are thrown away, gases from them (called chlorofluorocarbons, or CFCs) rise into the air and destroy some of the ozone in this layer. Most countries no longer produce CFCs, but the gas can stay in the atmosphere for years -- destroying ozone and adding to the greenhouse effect.
Each August, a hole in the ozone layer forms over Antarctica (it usually closes by December). Since it was discovered in the 1980s, it has doubled to about the size of North America. It sometimes extends over southern Chile and Argentina. On some days, people in Punta Arenas, Chile (the world's southernmost city), may limit their sun exposure to no more than 20 minutes between noon and 3 p.m. Other days, they don't go out at all!
Medioambiente: El aire que respiramos (Spanish Version)