Page 57 - Reading Success B3

Rain is always slightly acidic. This is because the Earth’s atmosphere naturally
contains substances such as carbon dioxide and sulfur dioxide, which dissolve in

moisture to form weak acids. When we burn fossil fuels, such as coal and oil,
either in factories or automobile engines, extra amounts of chemicals are added to

the atmosphere. Some of these chemicals can form acids. When a rain that falls
has a higher than normal acid content , it is called acid rain.

Dirt put into the air in one part of the world can affect other places, thousands of
miles, away. If a factory in one country gives off too much dirt, acid rain may fall

somewhere else. Scientists are not in agreement on exactly what harm is done by
the acid rain. They know that trees and soil and fish may suffer, and so may

buildings, since acid eats into stone.
Acid rain, like other kinds of air pollution, can be prevented in several ways. It

can be minimized by burning low sulfur fuels. Automobiles that burn lead free
gasoline are cleaner than automobiles that do not. The smokestacks of power

stations can be fitted with equipment to clean smoke and gases before they are
released into the air.

Main Idea

What is the main idea of this story?

a. how rain can affect air pollution

b. some ways to minimize acid rain
c. what makes rain acidic and how its acidity can be reduced

d. some causes of air pollution

60_Reading Success B 3