How does air become dirty? Your car produces emissions that go into the air. The factories that made materials for your car produce more emissions. All over the world, millions of cars and millions of factories emit soot, ashes and chemicals into the air. Still more of these substances come from garbage that is burned and chemicals that are sprayed.

The result is air pollution. Sometimes you can smell pollution and sometimes, when the air looks hazy or smokey, you can see it. But sometimes it's invisible.

Invisible or not, air pollution can cause a lot of damage. Even a little air pollution can make your eyes burn and your head ache. It can tire you out, blur your vision, make you dizzy, and make it hard for you to breathe. Air pollutants can also affect asthma and make it easier for you to catch a cold or the flu. Air pollutants have also been linked to some cases of serious disease such as lung cancer and heart ailments. In fact, some scientists believe that air pollution costs Americans billions of dollars a year in doctor bills and unearned paychecks due to pollution-related illness.

People are not the only ones hurt by air pollution. Plants surrounded by polluted air may not grow. Fish and animals may die. Statues and building materials may be discolored or corroded (eaten away).

Fighting Air Pollution

In the United States, people have been fighting air pollution for years and their efforts are working.

Industries must now control emissions from factories. New technology both in pollution prevention, emission reductions, and improved manufacturing methods cut down emissions and removes pollutants from emissions.

Cars now come equipped with something called a "catalytic converter" for the engine system. The converter changes the harmful hydrocarbons and carbon monoxide that a car produces when it burns fuel into harmless carbon dioxide and water. Since a car with a converter uses unleaded gas converters also reduce the amount of lead in the air.

Some states and communities require emission control systems in cars to be inspected every year to make sure they are working properly. This discourages drivers from removing catalytic converters from their cars, or from pumping leaded gas into a car that should only use unleaded. In most states it is against the law to switch from unleaded to leaded fuel, or to tamper with catalytic converters.

Thanks to these different kinds of emission controls, the air in the United States is better than it used to be. Amounts of most major air pollutants have gone down. For example, between 1975 and 1984 amounts of carbon monoxide and sulfur dioxide in the air dropped an average of more than 30 percent. The amount of lead dropped 70 percent. Today you can go outside to "get a breath of fresh air" in more and more places in the U. S.

New problems

Air quality is improving, but more work needs to be done. Scientists now believe that some problems are more serious than they first thought. For example, researchers are studying harmful effects of acid rain. When some emissions from factories and cars mix with sunlight and vapor in the air, they change into acidic compounds. These compounds can travel long distances in the air. Then they can fall to earth with rain, snow or dust. When they fall on lakes, they can turn the water acidic, like vinegar. In some lakes, all the fish died because the water became so acidic.

Another problem scientists are learning more about is indoor air pollution. The air inside your house may be more polluted than the air around a factory! Indoor air pollution can come from oven fumes, hair spray, cigarette smoke, insect sprays, fingernail polish, carpet cleaners and other ordinary household products. Even the dirt and rocks around a house can cause pollution if they contain radon. Radon is a radioactive gas that occurs naturally in some soil. It is colorless, odorless and tasteless, but some scientists believe it causes lung cancer.

Sometimes the simplest cure for indoor air pollution is just to open a few windows. More complicated methods may involve installing exhaust fans or plugging up holes in a house foundation so radon cannot seep through.