Chapter 22

Human Actions and the Atmosphere

22.1 Air Pollution

Lesson Objectives

• Describe the different types of air pollutants.


• Discuss what conditions lead some cities to become more polluted than others.


• Describe the sources of air pollutants.

Introduction

Earth’s atmosphere supports life by providing the necessary gases for photosynthesis and
respiration. The ozone layer protects life on Earth from the Sun’s ultraviolet radiation.
People also use the atmosphere as a dump for waste gases and particles. Pollutants include
materials that are naturally-occurring but present in larger quantities than normal. In
addition, pollutants consist of human-made compounds that have never before been found
in the atmosphere. Pollutants dirty the air, change natural processes in the atmosphere, and
harm living things. Excess greenhouse gases raise global temperatures.

Air Quality

Air pollution problems began centuries ago when fossil fuels began to be burned for heat
and power. The problem grew into a crisis in the developed nations in the mid-20th century.
Coal smoke and auto exhaust combined to create toxic smog that in some places caused
lung damage and sometimes death. In Donora, Pennsylvania in October 1948, 20 people
died and 4,000 became ill when coal smoke was trapped by an inversion. Even worse, in
London in December 1952, the “Big Smoke” killed 4,000 people over five days, and it is likely