Lemon juice and vinegar are familiar acids. Some acids are strong enough to burn your skin. Others are so weak it’s hard to tell them from water. In many parts of the world today, rain is a weak acid. This rain is called acid rain.
Acid rain is a kind of air pollution. When coal, oil, or gasoline are burned, they release harmful gases into the air. These gases mix with the moisture that is always present in the air and form weak acids. Wind can carry the acidic droplets huge distances. Eventually, these droplets return to the ground as acid rain or as acid hail, snow, sleet, or even fog.
Acid rain looks, feels, and tastes just like clean rain. For humans, walking in acid rain, or even swimming in a lake polluted by acid rain, is no more dangerous than walking or swimming in clean water. But acid rain is extremely harmful to the environment.
THE EFFECTS OF ACID RAIN
When acid rain gets into lakes and streams, it kills the fish and other animals and plants that live there. Many rivers in Scandinavia no longer have any fish. All the fish have been killed by acid rain.
Acid rain can also damage plants on land, including farm crops and forests. By the mid-1980s, acid rain had damaged or killed almost half of the trees in Germany’s Black Forest.
The outside surfaces of stone buildings and monuments can also be corroded, or worn away, by acid rain. Some of the world’s greatest buildings and monuments show signs of damage caused by acid rain. Acid rain eats away at the steel in bridges and railings as well.
WHERE DOES ACID RAIN COME FROM?
Acid rain is not natural, but it’s also not new. The problem began in the 1700s with the Industrial Revolution. It has been growing ever since. In the past, city air was sooty from thousands of coal fires. The soot turned buildings black and produced acid rain. Trees and other plants near large industrial cities were dead or dying. Today, people burn less coal, but there are many more fuel-burning power stations, cars, trucks, buses, and aircraft. All of these pollute the air and contribute to acid rain.
REDUCING ACID RAIN
Most of the gases that produce acid rain come from power stations, factories, and vehicles. Power stations and factory chimneys can be fitted with devices that remove these gases. Cars can be fitted with catalytic converters, which reduce the pollution in exhaust fumes. Unfortunately, the devices to reduce the acid gases are expensive. Not all governments, companies, and individuals are willing to spend the extra money on them.
ACID RAIN IGNORES BORDERS
Acid rain is blown by the wind. It does not recognize the boundaries of countries. Much of the acid rain in eastern Canada and the Northeastern United States, for example, comes from the factories and power stations in the Midwestern United States. Acid rain in Scandinavia may come from the United Kingdom. In China, acid rain now pollutes 40 percent of the country. It results from China’s rapid industrial growth and increasing use of coal. Even if we could stop producing the polluting gases that cause acid rain today, it would take years for acid rain’s effects to begin to disappear.