You may have some firsthand experience with air pollution, because almost every city--and even parts of the country--have polluted air.  How did the air get this bad?  Electricity production--the pollution generated by power plants--has contributed a lot to poor air quality.  Cars are another big problem.  While the cars made today pollute far less than cars made a few years ago, the are many more cars on the road today, and the typical car drives more miles each year than ever before.  As a result, air pollution from cars hasn't decreased much.

In some areas, such as Los Angeles, air pollution has become so bad that the government has been forced to restrict many everyday activities, including driving a car, having a barbecue, even mowing the lawn with a power mower.  All of these activities contribute to air pollution.

What's wrong with air pollution?  When the air gets too dirty, it can be uncomfortable to breathe, and with every breath you may be inhaling substances that can make you sick.  But even when the air is only a little polluted, the effects can still cause many illnesses, particularly among very young children and older adults like your grandparents.

When the Rain Becomes Poison

We used to count on a good rainfall to cleanse the air of pollutants.  Now, in some parts of the United States, even the rain is polluted.  We call it "acid rain," even though the problem also pollutes the snow, sleet, hail, and even fog!
What turns the rain into poison?  The problem comes primarily from the burning of fossil fuels, including gasoline burned in automobile engines and oil used for cooking and heating.  The biggest source is the burning of coal--especially certain kinds of coal that contain high levels of sulfur--in electric-generating plants.
All of these sources release either sulfur dioxide or nitrogen oxides.  Once in the air, these two substances mix with other chemicals and water to form sulfuric acid.  When these chemicals mix with moisture, they fall to Earth, where they can cause a great deal of harm.
What happens to acid rain when it reaches the ground?  For one thing, it poisons fish and other things that live in rivers, lakes, and streams.  It also kills trees.  Buildings and monuments can also be affected.  Some of the oldest and most treasured buildings in the world have been found to have damage caused by acid rain.