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22.1: Air Pollution

Difficulty Level: At Grade Created by: CK-12

Lesson 22.1: True or False

Name___________________ Class______________ Date________

Write true if the statement is true or false if the statement is false.

_____ 1. Air pollution is caused completely by human actions.

_____ 2. The air in the U.S. is more polluted now than it was 50 years ago.

_____ 3. Livestock wastes pollute the air with methane.

_____ 4. Animal wastes add particulates to the atmosphere.

_____ 5. Particulates include only particles big enough to be seen by the unaided eye.

_____ 6. Ozone forms when certain air pollutants are heated by direct sunlight.

_____ 7. Paints and petroleum products release volatile organic compounds.

_____ 8. Air pollution contributes to global warming.

_____ 9. In California, mountain ranges can trap polluted air over cities.

_____ 10. All primary pollutants come from directly from motor vehicles and smokestacks.

Lesson 22.1: Critical Reading

Name___________________ Class______________ Date________

Read this passage based on the text and answer the questions that follow.

How Pollutants Enter the Atmosphere

Most pollutants enter the atmosphere when fossil fuels burn. Some pollutants are released when forests burn. Others evaporate into the air.

The burning of fossil fuels releases many pollutants into the air. These pollutants include carbon monoxide, carbon dioxide, nitrogen dioxide, and sulfur dioxide.

  • Motor vehicles account for almost half of fossil fuel use. Most vehicles run on gasoline, which comes from petroleum.
  • Power plants and factories account for more than a quarter of fossil fuel use. Power plants burn fossil fuels to generate electricity. Factories burn fossil fuels to power machines.
  • Homes and other buildings also burn fossil fuels. They use fossil fuels for heating, cooking, and other purposes.

Millions of acres of forest have been cut and burned to make way for farms. The burning of trees produces most of the same pollutants as the burning of fossil fuels.

Volatile organic compounds, or VOCs, enter the air by evaporation. VOCs are found in many products, including paints and petroleum products. The VOC called methane evaporates into the air from livestock waste and landfills.


  1. List three general sources of pollutants that enter the atmosphere.
  2. Identify air pollutants produced by the burning of fossil fuels.
  3. Where and why are fossil fuels burned?
  4. Describe air pollution from the burning of forests.
  5. What are VOCs? How do they enter the atmosphere?

Lesson 22.1: Multiple Choice

Name___________________ Class______________ Date________

Circle the letter of the correct choice.

  1. The worst air pollution in the U.S. occurs in
    1. New York State.
    2. New Jersey.
    3. California.
    4. Florida.
  2. The “Big Smoke” was an incident of deadly air pollution that occurred in the mid-1900s in
    1. Los Angeles.
    2. San Francisco.
    3. Mexico City.
    4. London.
  3. In the U.S. today, air pollution comes from
    1. vehicles.
    2. factories.
    3. power plants.
    4. all of the above
  4. Most primary pollutants are released by
    1. volcanic eruptions.
    2. natural processes.
    3. human activities.
    4. forest fires.
  5. Pollutants released into the air when fossil fuels burn include
    1. carbon monoxide.
    2. carbon dioxide.
    3. particulates.
    4. all of the above
  6. Smog consists mainly of
    1. smoke.
    2. particulates.
    3. water vapor.
    4. none of the above
  7. Almost half of the fossil fuels that are burned are used by
    1. factories.
    2. power plants.
    3. cars and trucks.
    4. homes and other buildings.

Lesson 22.1: Matching

Name___________________ Class______________ Date________

Match each definition with the correct term.


_____ 1. type of pollutant that forms when other pollutants undergo chemical reactions

_____ 2. primary pollutant that is a carbon compound such as methane

_____ 3. type of pollutant that enters the air directly

_____ 4. solid particle in the air

_____ 5. measure of the pollutants in air

_____ 6. brown haze that forms in air when certain pollutants react together in sunlight

_____ 7. primary component of photochemical smog


a. air quality

b. photochemical smog

c. primary pollutant

d. VOC

e. particulate

f. ozone

g. secondary pollutant

Lesson 22.1: Fill in the Blank

Name___________________ Class______________ Date________

Fill in the blank with the appropriate term.

  1. In the U.S., the 1970 __________ Act placed limits on what can be released into the air.
  2. Pollutants called sulfur oxides are released mainly when __________ burns.
  3. Ash and dust are examples of common __________ in air.
  4. Most pollutants enter the air when __________ burn.
  5. VOCs enter the air by __________.
  6. Poor air quality started to become a problem after the _________, when coal-burning factories became common.
  7. Mercury and lead are toxic heavy __________ that may pollute the air.

Lesson 22.1: Critical Writing

Name___________________ Class______________ Date________

Thoroughly answer the question below. Use appropriate academic vocabulary and clear and complete sentences.

Photochemical smog forms more often in the summer than in the winter. Explain why.

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