Page 27 - Reading Success B1

A large city, even on a warm sunny day, may sometimes be covered by hazy
mist, or even by a dense gray cloud. The mist is polluted. It is smog - a mixture of

smoke and fog - an especially unpleasant kind of air pollution. Smog is harmful. It
often causes shortness of breath , dizziness, watery eyes, and a runny nose.

Smog can also be dangerous if it is extra thick and if it lasts a long time. In the
days when people burned coal for cooking, heating, and in factory furnaces, cities

were often covered in smoke.
Wind carries many substances through the Earth’s air. Among them is pollen

from plants, sand from dry beaches, and dust from fields. These are natural
substances. However, humans have added other substances to the air. Smoke

pours from factory smokestacks. Chemical fumes rise from paper mills and metal
working plants. Garbage dump incinerators spread black soot. Automobiles

stream a blue, smelly haze that hangs over crowded cities. The air is polluted
when it is filled with unnatural substances.

Main Idea

What is the main idea of this story?

a. noise pollution

b. air pollution
c. water pollution

d. air position

30_Reading Success B 1