Lesson Visible Air Pollution:
You've Got to See It to Believe It!

Learning Objectives

After this lesson, students should be able to:

• Identify the two major types of visible pollutants, smog and particulate matter.
• Understand and explain how air pollutants are generated.
• Understand and explain how smog forms.
• Describe how engineers interact with visible air pollution.

Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

NGSS: Next Generation Science Standards - Science

International Technology and Engineering Educators Association - Technology

State Standards

Worksheets and Attachments

Introduction/Motivation

Before the Lesson — Not Your Average Toe Cheese!

• (Optional) Create an air pollution bulletin board that includes definitions and examples of the vocabulary terms. See the Air Pollution Bulletin Board Example attachment.
• Prepare the sock(s). Place a white sock over the tail pipe of your car. Be sure the tail pipe is cool (the car should NOT have been running recently). Turn on your car and run it for a minute or so. Then turn the car off and wait a minute or so to let the tail pipe cool before removing the sock. This may take longer with newer cars. DO NOT breathe the car exhaust.
• Set up a designated area in your classroom (bulletin board, specific table, etc.) to display the sock with an attention-getting title such as "What is this?" or "It's not your average toe cheese!" Supply the area with the sock, a magnifying glass, voting ballots (use the Voting Ballots attachment) and a ballot box (a covered shoe box works great). Scaling idea: For less advanced students, adapt the ballots to have the students draw pictures of their observations.

With the Students

• During the course of the lesson (or a longer period of time) ask students to observe the sock with the magnifying glass.
• Ask them to write down (on their ballot) what they observe.
• Ask students to hypothesize where the "sock pollution" came from. Encourage them to support their guess with evidence from their observations.

Lesson Background and Concepts for Teachers

The atmosphere is almost completely composed of invisible gaseous substances. Some of these gases pollute the air. Although most major air pollutants are invisible, particulate matter and smog can easily be seen, often from many miles away, especially when large amounts concentrate in cities. Because visible pollutants are more obvious, we understand a lot about them and they are heavily regulated by the U.S. Environmental Protection Agency.

Particulate Matter

Have you ever noticed a sunbeam with millions of little specks of dust floating in it? That is particulate matter. Particulate matter, often visible in the air, is tiny particles of solid matter and/or droplets of liquid. Natural sources of particulate matter include pollen, volcanic ash and dust blown by the wind. The primary sources of man-made particulate pollutants are the coal and oil burned by factories and power plants, and the hydrocarbon fuels burned by vehicles.

A close look at the particulate matter of air pollution, such as soot, car exhaust, ash and asbestos, reveals how different from each other these particulates look at the microscopic level. They vary greatly in size, shape and color. To show the students, use the Microscopic View of Air Pollutants attachment to make an overhead transparency or color print of some examples.

The U.S. has more than 150 million cars — think about how much pollution that creates! Other smaller-scale, but equally important, local sources of air pollution include the wood burned in fireplaces and wood-burning stoves. Some cities, such as Denver, CO, often have days when wood burning is restricted because of how much it contributes to poor air quality.

Particulate matter is harmful to people and animals who breathe it, and to the surfaces of buildings and other structures that are exposed to it for long periods of time or in large concentrations. For example, the Sistine Chapel in Rome, Italy, painted by Michelangelo, was dirtied over the centuries by air pollution from burning candles.

Smog

The word "smog" comes from the combination of the words "smoke" and "fog." It was first used in the early 1900s to describe the combination of smoke and thick fog that sometimes hung over the skies of London, England. Smog is a type of visible air pollution created from smoke, fog, suspended particles and chemical fumes. London-type smog comes from moisture in the air condensing on the smoke/chemical-suspended particles and forming tiny smog droplets. Refer to the associated activity Particulate Matter: For Your Eyes Only for students to develop their understanding of visible air pollutants with an incomplete combustion demonstration, a "smog in a jar" demonstration, and by building simple particulate matter collectors. 

Weather conditions, such as a lack of wind or a thermal inversion, can cause smog to build up. Smog is especially obvious during a thermal inversion, when an upper layer of warm air traps the pollutants over a lower layer of cool air, preventing normal atmospheric circulation (the smog cannot rise and scatter). Mountain ranges near cities may also trap smog in an area.

There are two types of smog: photochemical smog and industrial smog. Photochemical smog occurs when strong sunlight reacts with air pollution such as the hydrocarbons and nitrogen oxides released from vehicles and power plants. The sun "bakes" the chemicals into the brownish-orange haze often seen in the skies above large cities. Low-level ozone is a major component of photochemical smog (do not confuse low-level ozone with upper-level ozone, which helps filter out harmful rays from the sun). Industrial smog contains sulfur oxide and solid particles that are released when fossil fuels are burned. It appears as a grayish haze in the skies above heavily industrialized cities.

Sometimes Hawaii has "vog" alerts — times when volcanically-produced smog is at dangerous levels.

What are Engineers Doing?

Engineers are continually working to help prevent smog and particulate matter pollution. One mechanical engineering invention is a catalytic converter that reduces smog by changing hydrocarbons and carbon monoxide in automobile exhaust into carbon dioxide and water vapor. While this is an improvement, high levels of carbon dioxide are still bad for human health and the environment so engineers continue to explore new ideas. One idea is to use energy from the sun — solar power — to run our cars and heat our homes. Another idea is to take advantage of the wind to create energy for use in factories, instead of burning coal or other fossil fuels. Students can play their part to spread the word with the literacy-based activity Green Marketing where they learn basic marketing concepts and techniques, and the principles of comparative analysis, while creating an advertisement for a hybrid vehicle. 

Associated Activities

• Particulate Matter: For Your Eyes Only - Students develop their understanding of visible air pollutants with an incomplete combustion demonstration, a "smog in a jar" demonstration, and by building simple particulate matter collectors.

  Watch this activity on YouTube

Lesson Closure

Class Discussion

1. As a class, read and discuss the results of the student ballots.
2. Ask the students if any of them would change the responses on their ballots based on what they learned during this lesson.
3. Reveal the source of the sock pollution. (Answer: Directly from the tail pipe of your running car.)
4. Discuss what actually comes out of cars' exhaust pipes, both visible and invisible. (Answer: carbon dioxide – CO₂, carbon monoxide – CO, hydrocarbons and nitrogen oxides.)
5. Where does the exhaust usually go? (Answer: Into the atmosphere.)
6. Ask students to imagine millions of cars, right now, releasing pollution into the atmosphere. Remind them that engineers continue to work to improve fuels and engine efficiency to reduce these types of pollutants. Older cars, trucks and SUVs "give off" more pollution than newer cars.
7. What are some ways engineers are reducing air pollution from cars? (Possible answers: Electric cars, hybrid gas and electric cars, increased fuel efficiency in vehicles.)
8. How can you help engineers to reduce air pollution? (Possible answers: Ride your bicycle or walk instead of taking the car, recycle and reuse items so fewer items need to be produced in polluting factories.)

Vocabulary/Definitions

catalytic converter: An emission-control device that changes hydrocarbons and carbon monoxide in automobile exhaust into carbon dioxide and water vapor.

hydrocarbon: An organic compound containing atoms of hydrogen and carbon.

industrial smog: Contains sulfur oxide and solid particles that are released when fossil fuels are burned. It often appears as a grayish haze in the skies above heavily industrialized cities.

particulate matter: Very small particles of solid matter and/or droplets of liquid. It includes materials that have been burned (ash, smoke, soot), dust, pollen, soil or chemicals — anything that floats in the air.

photochemical smog: Appears as a brownish-orange haze often seen in the skies above large cities. Occurs when strong sunlight reacts with air pollution such as the hydrocarbons and nitrogen oxides released from vehicles and power plants. Ozone is a major component of photochemical smog.

pollutant: A harmful chemical or waste material that contaminates air, soil or water.

smog: A combination of smoke and fog in the air.

thermal inversion: When an upper layer of warm air traps the pollutants over a lower layer of cool air, preventing normal atmospheric circulation.

visible pollutant: Air pollution that can be seen with the naked eye.

Assessment

Pre-Lesson Assessment

Demonstration: Prepare for the Not Your Average Toe Cheese! classroom demonstration / activity as described in the Introduction/Motivation section.

Post-Introduction Assessment

Observation: Have students examine the sock and record their observations as directed in the Introduction/Motivation section.

Lesson Summary Assessment

Discussion: During lesson closure, have students identify which type of visible pollutants they found on the sock. (Note: In the lesson Invisible Air Pollution: I Don't Believe My Eyes!, students learn more about the invisible pollutants.)

Homework

Cartoon Character: Student assignment: Over the years, cartoon characters, such as Bugs Bunny, have often informed us about environmental issues. Create your own cartoon sketch of a character dealing with pollution. Your character could be modern or futuristic, a pollutant or a pollution fighter. Make sure to name your character and have it saying something about how the pollution is affecting them.

Internet Search: Assign students one vocabulary term each and have them research it on the Internet. Lead a small discussion of student findings during the next class period.

Lesson Extension Activities

Variations to the Not Your Average Toe Cheese! activity:

• Make more polluted socks and have groups of students observe them. As a class, discuss their ideas for the origination of the pollutants.
• Collect pollutants in the sock as a live demonstration in your school parking lot. Be sure the kids are on the sidewalk and that only an adult handles the sock and starts/stops the car.
• Compare the exhaust of different types (make and year) of cars. Does it make a difference? Conduct an emissions sock test before and after a car's tune-up.

Take a field trip to an emissions testing site. Or, invite a speaker from an emissions testing site to speak to your class about how they measure the vehicle exhaust pollutants. What determines whether a car passes or not? See the lesson I've Gotta Get Some Air, for information on how we clean up indoor air pollutants, and Pollution Solutions, for information on how we clean up outdoor air pollutants.

References

Copyright

Contributors

Supporting Program

Acknowledgements

The contents of this digital library curriculum were developed under a grant from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education and National Science Foundation GK-12 grant no. 0338326. However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.