Got Dirty Air?: For Your Eyes Only

3月 20 2011

Source: TeachEngineering Digital Library

Summary Information

Keywords:

air pollution, air, pollution, atmosphere, smog, particulate, combustion, environment, visible pollutants, particulate matter, smog, industry, technology

Topic:

Earth Science

Measurement

Biology

Target Grade (Ages):

Grade 6 (Ages 11-12)

Grade 7 (Ages 12-13)

Estimated Time Required:

2-3 hours

Diversity Indicators:

This lesson is appropriate for all learners. Be conscious of students with asthma or allergies if you collect air pollution data outside.

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LESSON

Goals and Prerequisites

Goals:

To introduce students to common types of air pollution and their sources
To explain the role of engineering in monitoring air quality and designing technology that helps clean air
To allow students to collect and record local particulate matter data

Prerequisites:

Students should:

Be familiar with the scientific method
Be able to identify some man-made sources of air pollution
Have some understanding of the affects of air pollution on humans and their environment.

Instructional Objective(s)

At the end of the lesson, students should be able to:

Define air pollution. Identify some ways to reduce air pollution
Understand the roles of engineers in the field of air pollution
Describe how engineers create technology to help study air pollution and help industry clean up their air pollution
Identify the two major types of visible pollutants, smog and particulate matter
Understand and explain that air pollutants are generated during incomplete combustion
Build a simple particulate matter collector.

Instructional Resources

Background:

Introduction/Motivation

Clean air contains only the gases and water vapor needed to keep the Earth's environment healthy. Pollutants are substances, or even energy, that harm living — and some non-living — things. A high concentration of pollutants in the air is called air pollution.

Air pollution can destroy our environment and can cause humans and other living things to become sick. Sometimes, air pollution can cause rashes, eye/nose irritation, headaches, sleepiness, coughing, sneezing and dizziness. If you breathe in too much air pollution, of a very high concentration, it can cause severe illnesses, such as cancer, asthma, kidney failure, liver damage and even birth defects. Air pollution negatively affects the plants and animals in our environment as well.

Air pollution can even destroy buildings. Particles of pollution may coat a building, making it look dirty. Pollution can also cause acid rain that can eat away at buildings

Engineers that work on air pollution problems must have a good understanding of the composition and characteristics of air before beginning to design technology solutions for air pollution. Some of the technologies that engineers have designed to clean up air pollution include a scrubber, an electrostatic precipitator, a cyclone and a baghouse.

What are Air Pollutants?
There are literally hundreds of pollutants that float around at any given time in the air that we breathe. Some of these pollutants come from natural sources, but most come from human activity. Air pollution consists of the gases and particles that affect the quality of the air around us, are harmful to the environment, and/or enter the atmosphere at highly concentrated levels. Air pollution generally consists of: visible gases, invisible gases and particulates (such as, soot), as well as fibers, mists, molds and bacteria. These particulates can be found both outdoors and indoors. Most major air pollutants are invisible (like carbon dioxide and carbon monoxide but large amounts of them can be seen as smog when they are concentrated in areas such as cities. Because visible pollutants (like particulate matter and photochemical smog) are more obvious, we understand more about them and tend to have more regulations focusing on them than we do on invisible pollutants.

Particulate Matter
Particulate matter is often invisible to the naked eye unless it is very concentrated. To study the particulates more easily, it is possible to "catch" and identify some of them by concentrating them on a collector. Engineers use a variety of technologies to measure concentrations of and identify types of particulate matter. Engineers must first learn this information about a pollution site before working towards cleaning up the pollutants. Engineers also use this information to help design new technologies (new fuel types, more efficient engines, process treatments in industrial applications, etc.) that more effectively prevent and reduce air pollution.

Photochemical 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 London, England. Today, smog really refers to photochemical smog,a combination of Volatile Organic Compounds (VOCs) and Nitrogen Oxides. When exposed to sunlight, photochemical smog creates tropospheric ozoneand other irritants. Weather conditions, such as lack of wind can cause smog to build up. Smog is especially obvious during a thermal inversion that prevents the smog fromrisingand scattering). Mountain ranges near cities can also trap smog in an area.

Sources of Air Pollution (Outdoor/Indoor)

Man-Made Outdoor Sources
The burning of fossil fuelsis one of the main causes of air pollution and is a major contributor to global climate change. Smoke and fumes containing carbon dioxide and sulfur dioxide from power stations and factories are the worst offenders. Car exhaust is another large source of air pollution. It contains both invisible gases (carbon dioxide, carbon monoxide, hydrocarbons, and nitrogen oxides) and particles. Many consumer products (hair spray, paint and cleaners) release high levels of volatile organic compounds(VOCs) into the atmosphere. Other important sources include gas stations, industry (many types), agriculture and forestry.

One of the greatest sources of air pollution is the incomplete combustion of gasoline in car engines. The engines are only about 30% efficient; this means that for every 10 gallons of gasoline in the tank, only three gallons are actually used to move the vehicle! Some of the remaining gas heats the engine and some is pushed out of the engine unburned. This inefficiency is one of the largest contributors to photochemical smog. If gasoline were completely burned, the only by-products would be water vapor and carbon dioxide. Carbon dioxide can still be harmful to the environment when emitted in large amounts, but complete combustion limits the number of other harmful gases released into the atmosphere. Engineer-designed devices that reduce pollution emissions include catalytic converters, modified fuels and more efficient engines.

Natural Outdoor Sources
Volcanic eruptions often spew gases and ash into the atmosphere. Forest fires also release dust and smoke into the air.

Indoor Sources
Indoor air pollution is becoming a large concern of environmental engineers because the majority of the public's time is spent indoors. Indoor air (IA) pollutants can be created within the building or drawn inside from outdoor sources. Indoor sources include: equipment (malfunctioning HVAC systems, emissions from office equipment/labs), furnishings (new carpet that releases formaldehyde and burnt Teflon pans), dust-producing or water-damaged materials, unsanitary trash emissions, insects and pests (pesticides), food preparation areas, fungi, cleaning materials, pets (dander), and people (smoking). Some of the most common outdoor air pollutants that are brought inside are: smog, bacteria and mold spores, vehicle exhaust, exhaust fumes, pollen and dust, algae (from standing water) and smoke

Sound and Light Pollution
Some people also consider sound pollution a type of air pollution, because sound waves travel through the air. Outdoor sources include loud jets, construction equipment, huge trucks and other forms of transportation, etc. Indoor sources include music, TVs, mixers, dishwashers, washing machines, etc. Lights are also considered a source of air pollution to astronomers. Both sound and light pollution can affect human health as well as the health and migration patterns of animals.

What Are Air Pollutant Solutions?
To help inform this discussion, you may be interested in viewing the Asthma Free School Zones video below for your own edification or to share with your students in class.

Asthma Free School Zones

The water cycle usually cleans air pollutants naturally. Currently, however, there are two problems with this: the water cycle is unable to clean contaminants as quickly as they are added, and high concentrations of pollutants contribute to acid rain.

Governments around the world are attempting to help control air pollution by passing laws, such as the Clean Air Act in the United States or the European Union’s Directive on Ambient Air Quality and Cleaner Air for Europe. Many governments also pass strict legislation to control the amount of by-products released by industrial companies and modes of transportation. These air quality standards are designed to protect the health and welfare of people, plants and animals, and to protect buildings, monuments, water resources, etc. In order to enforce these laws, however, it is important to monitor air quality over time.

One of the largest problems environmental engineers face is creating new techniques to prevent additional air pollution. In the U.S., there are many changes that have occurred as a result of the passing of new environmental laws. For example, many places used to burn coal as a means of heating or running machinery. Now, we know that burning coal (and other fossil fuels) causes air pollution, and many people do not burn coal as a result of public awareness and stricter air emissions laws. Another example is with the engineering of automobiles. Generally, most cars still burn gasoline (a fossil fuel), which, as we know, is a cause of air pollution, but new laws have changed how cars are built. In the last 25 years, there have been major improvements in motor vehicle technology that have led to exhaust emission reductions of up to 96% compared to vehicles from 1960.

Informed citizens are also making adjustments on a more personal level to help improve the air. For example, many of us are reducing fuel use by joining a car pool, taking the bus/train, riding a bike or walking, reducing the energy we use, and buying environmentally friendly products, like non-aerosol hair spray and non-toxic cleansers that will all help in the efforts to reduce air pollution.

Air Pollution Factoids

Mexico City is one of the world's most polluted cities. When the air pollution is at its worst, birds have been known to drop dead out of the sky.
Every day, each of the world's 11 billion cattle gives off 1 pound of methane (produced in their gut as they digest food). That means 274 billion pounds (137 million tons) of methane is produced each year! Methane is also produced in large quantities by rotting vegetation in landfills. Methane is a major greenhouse gas and contributes to climate change.
The American Lung Association believes that sulfur-dioxide exposure (one source is the internal combustion engine of autos) is the third leading cause of lung disease,following smoking. It has also been implicated in the rising occurrence of asthma, bronchitis and emphysema. The average person takes about 20,000 breaths a day.
Plants give us oxygen, and yet people have destroyed almost two-thirds of the original forests on Earth.
Sometimes Hawaii has "vog" alerts. These are times when volcanically produced smog is at dangerous levels.

Materials:

Demo 1 - Incomplete Combustion Demonstration

1 utility candle
1 tin can (soup can)
Matches
1 straw
Paper towel or rag
Hot mitt

Demo 2 - Smog Demonstration

1 large glass jar
Aluminum foil
2-3 ice cubes
1 cup of water
Paper
Ruler
Scissors
Matches

Student Activity - Building Particulate Matter Collectors

Each group needs:

1 small glass jar (spice jar or baby food jar)
1 large glass jar (pickle, mayo or mason-type jar)
Petroleum jelly
Masking tape
Magnifying glass
1 index card
If you are allowing students to design their own collectors, you should provide other materials such as milk cartons, vegetable oil, hole punchers, etc.

For the entire class to share:

Chart paper (large, bulletin-board sized)
Colored construction paper
Scissors
Transparent tape

Procedure:

Before the Activity

Demo 1: Incomplete Combustion Demonstration: Practice the process a few times before demonstrating it to the class.
Demo 2: Smog Demonstration: Practice the process a few times before demonstrating it to the class. The critical step has to be done quite quickly.
Student Activity: Building Particulate Matter Collectors: Consider testing possible collection sites for the particulate matter collectors before the experiment. Some sites may not result in a lot of visible particulates and this can frustrate the students.

With the Students

Before doing the demonstrations with your students, you may want to view the Demonstration video below.

Demonstration video

Demo 1: Incomplete Combustion Demonstration

Incomplete combustion in cars is one of the leading sources of air pollution. This demonstration can be used to introduce students to this common source of pollution.

Light the candle.
Place the bottom of the tin can directly over the flame for a few seconds. The top of the flame should be almost touching the can. (Click on Figure 1 below.)

Figure 1
Look at the bottom of the can. Ask students what they see. (Answer: Black, sooty area.) Have the students record their observations in their journals. Do you think this is evidence of pollution? (Answer: Yes.)
Clean off the bottom of the can with a paper towel. (Click on Figure 1 above.) Have students also observe the pollution on the towel.
Repeat the procedure, but use the straw to gently blow air on the bottom of the can. Be careful not to blow the flame out. (Click on Figure 2 below.)

Figure 2
Look at the bottom of the can and ask students what they see. (Answer: Nothing or perhaps some water vapor condensing on the bottom of the can.) Do you see any pollutants? (Answer: No.) Have students record their observations and responses in their journals.
Ask students how the additional air affected the combustion of the candle. (Answer: Complete combustion takes place, producing only carbon dioxide and water vapor. Other types of pollutants are avoided.) Have students record their responses.

Demo 2: Smog Demonstration

Cut a strip of paper about 15 cm x 1 cm. Fold the strip in half lengthwise and twist it.
Use a piece of aluminum foil to make a "lid" for the jar. Mold it to the shape of the jar opening and then remove it and set it aside.
Put some water in the jar and swirl it around until the inside walls of the jar are wet.
Put the ice cubes on top of the foil to make it cold.
ATTENTION: All the parts of this next step must be done very quickly! Light the strip of paper and drop it and the match into the jar. Place the foil lid on the jar and seal it as tightly as possible. Place the ice cubes back on the middle of the foil lid. (Click on Figure 3 below.)

Figure 3
Ask students to describe what they see in the jar. How is it like real smog? How is it different? Ask students to write their responses in their journals.

Safety note: Do not breathe the "smog." Be sure to release it outdoors when you are finished with the demonstration.

Student Activity: Building Particulate Matter Collectors

This activity can be very structured or very open ended. You can have the class follow the collector design described below, or encourage them to design their own collector using any materials you choose to provide. A number of alternate collector designs are included at the end of the procedure. You can also have students design their own experiments where they test a number of different collection sites, or test different collector designs at the same site.

Divide the class into student pairs. Distribute supplies to each group (1 small jar, 1 large jar, petroleum jelly, masking tape).
Demonstrate the collector set up. (You can place the lid on this collector and keep it in the classroom as a control.)
Smear petroleum jelly on the outside of the small jar.
Carefully place the small jar inside large jar.
Use the masking tape to make a label for the large jar; include name, date and test site location.
Decide on several locations around the school — inside and outside — at which students think visible pollutants may be found. Assign each group to a different collection site. (Possible locations: Near a road or parking lot, a garage with car exhaust, a sandy/dusty playground, teachers' lounge or where people take smoking breaks, a stove, the classroom air filter/vent or the school's air intake/vent, etc.) Keep in mind that the collectors may have to stay at each site, undisturbed, for a few days.
Ask students to make predictions about which area will have more visible pollutants and why. Have students record their predictions in their journals.
Place jars in the test sites for several days. Have the groups check the jars daily and record observations in their journals.
On the final day of observations, bring the jars back to the classroom for comparison.
Have students observe the amount of pollutants on their collectors.
Have students rank the jars from the one with the fewest visible pollutants to the one with the most, lining them up across a counter or table. Remember to include the control jar. Ask students to record this information in their journals.
Discuss why certain areas have more visible pollutants than others.
Remind students that these particles are in the air they breathe. Ask them to write about how they feel about this in their journals.
Make a school map on large chart paper. For each test site, cut a jar shape from colored construction paper and write on it the ranking, location and number of particles collected (if possible to count). Adhere each cut-out jar to the correct location on the map. What conclusions can you draw from the map? Write a few of these conclusions neatly on index cards. Display the map and index card conclusions in a school hallway for others to see.
Consider holding a classroom discussion and/or a making writing assignment about possible sources of the particles. How can we make the air more desirable to breathe?

Alternate Collector Designs

Cut rectangular strips from plastic milk jugs or index cards and hole-punch one end to make a hole for a string hanger. Smear petroleum jelly on one side. Leave hanging for a week or more. Be sure to apply a thick coat of petroleum jelly to prevent the jelly from drying out over the course of the experiment.
Use index cards with a hole cut in the middle (about size of a silver dollar). Cover the hole in transparent tape so the sticky side is exposed. Hole-punch one end to make a hole for a string hanger. Make three cards for each site (one for 24 hours, one for three days, one for one week). Note: The index cards are not wet weather resistant, so be sure they are placed in protected areas.
Experiment with using clear vegetable oil instead of petroleum jelly in the collectors.

Safety Issues

Make sure you place collectors in low-traffic areas as to avoid having unaware students and school visitors tripping or breaking the glass.
Demos 1 and 2 use matches and fire; they should not be conducted by students without adult supervision.

Troubleshooting Tips

This activity is not a rapid or neat experiment. To obtain significant results, the jars need to be placed in very dirty areas.
Set the collectors on white paper while observing them; it makes the particulates easier to see.

Extensions

In Demo 1, compare the different types and amounts of pollution created from burning different brands and types of candles. For example, paraffin wax vs. beeswax.

Post a chart listing the causes of visible pollutants and what can be done to prevent them. Leave the chart up so students can add to it whenever they have an idea.

For the student experiment, try all the different types of collectors in the same place. Does one type do a better job (collect more pollutants)? Do they each attract a different type of pollutant?

Have students make a bar graph showing the quantity of pollutants (vertical) vs. the jar locations (horizontal). What conclusions can you draw from the graph?

Find our about factories in your area. What do they make? What types of waste do they produce? How do they dispose of the waste? In the U.S., you can check them out on the EPA website.

Invite someone from the EPA (or other local person responsible for monitoring air quality) to your classroom. Encourage students to ask questions about the types, causes, and levels of air pollution in your community.

Other suggestions to extend this activity can be found at TeachEngineering, including the original Got Dirty Air? lesson.

Assessments and Rubrics

If you are interested in learning how to make your own rubric for this or other lessons, you may be interested in watching the How to Make a Rubric video below.

How to Make a Rubric

Or, you can choose to use or customize the one created for this lesson plan below.

Got Dirty Air Rubric (XLS)

Got Dirty Air Rubric (PDF)

Pre-Activity Assessment

Class Discussion Question: What does air pollution look like? What are causes of air pollution?

Activity Embedded Assessment

Student Observations: During the activity, ask students for their observations, as directed in the Procedure section.Observe what students are writing and drawing in their notebooks.

Post-Activity Assessment

Informing Others / Map Making: Make a school map on large chart paper. For each test site, cut a shape from colored construction paper and write on it the ranking and location. Adhere each shape to the correct location on the map. What conclusions can you draw from the map? Write a few of these conclusions neatly on index cards. Display the map and index card conclusions in a school hallway for others to see.

External Resources

Environmental Education for Kids: Read about a chemical engineer who works in the air pollution field.

Environmental Protection Agency, Indoor Air Quality Tools For Schools Kit: Free resources that enable students to investigate how they can improve their school's indoor air quality.

Project A.I.R.E.: Student appropriate reading on the topic of air pollution.

TeachEngineering Digital Library: Original Got Dirty Air? lesson

The United Nations Statistics Division: Information about air pollution around the world.

Credits

This material was adapted from the Got Dirty Air? lesson, created through the Integrated Teaching and Learning Program at the College of Engineering and Applied Science at the University of Colorado at Boulder. The TeachEngineering Digital Library is a free, online collection of teacher-tested K-12 engineering activities, lessons and units aligned to educational STEM standards, funded primarily through the National Science Foundation.

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