BioEd Online

Teacher Background

Dust and other particles found indoors can come from a variety of sources and may include cigarette smoke, animal dander (flakes of dead skin), insect parts, mold spores, fibers, and/or dust mites and their droppings.

Indoor dust can pose a significant health problem to individuals who are allergic to any one of the particles it contains. Animal dander, mold spores, and dust mites are especially common indoor allergens (allergy-causing agents). They can cause simple allergies of the upper respiratory system (“hay fever” symptoms). Dust mites also have been linked to allergic diseases of the airways, such as asthma.

Several measures can help to control dust in indoor environments. Filters remove larger particles from the air. Keeping living areas dry and well ventilated also helps to limit the growth of molds (and dust mites that can feed on molds), which prefer damp places. Eliminating curtains and other materials that hold dust may be necessary, in some cases, to control allergies in susceptible individuals.

Objectives and Standards

Concepts

• Dust consists of individual particles of different substances.

• Even air that appears to be clean may contain dust and other pollutants.

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Science, Health, and Math Skills

• Observing

• Measuring

• Estimating

• Graphing

• Drawing conclusions

Materials and Setup

Teacher Materials (see Setup)

• baking soda (or cornstarch, baby powder, or dusty eraser)

• cotton balls

• flashlight with batteries

Materials per Group of Students

• glue sticks

• plastic knife (or spreader)

• petroleum jelly

• wax paper

Materials per Student

• hand lens (magnifier)

• pair of scissors

• rubber band, large

• prepared sheet of construction paper

• sheet of marked graph paper, 10 cm x 10 cm

• copy of student sheet

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Setup

1. Assemble a “dust catcher,” as described on the “Make a Dust Catcher” student page, for the students to use as a model when they construct their own.

2. To facilitate sharing of materials, organize students into groups of four. Each student should make his or her own dust catcher.

3. Cut the construction paper (9 in. x 12 in.) in half horizontally to make 4½ in. x 12 in. sheets.

Procedure and Extensions

Time

30 minutes to make collectors; 30–45 minutes to observe particles; 30–45 minutes to make graphs

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Session 1: Dust Catchers

1. Create a small cloud by shaking a cotton ball dipped in baking soda (or cornstarch or baby powder, or use a dusty eraser; see PDF for Safety note). Shine a flashlight through the dust cloud. Ask, What are we seeing? Do you think this is always in air? How could we find out?

2. Show students the dust catcher that you have made and explain that they will each make a similar one to take home. They will place the dust catchers in areas of their homes that they predict will have the most air pollution. After one or two weeks, they will bring the dust catchers back to school and examine them for particles.

3. Guide students as they construct their dust catchers, following steps described on the “Make a Dust Catcher” student sheet.

4. Have students take their dust catchers home and place them on a flat surface to catch dust for one or two weeks.

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Session 2: Observing

1. When all students have brought their dust catchers back to school, open a general discussion about the appearance of the dust catchers. (Some will have a visible sprinkling or layer of particles; others will have few or no visible particles.)

2. Have the Materials Managers collect enough hand lenses for their groups. Each student should examine the overall appearance of the dust on his or her collector and, if time permits, on the collectors of other members of the group.

3. Have each student use a magnifier to count the number of particles in 10 squares chosen randomly on the grid. (You may need to vary the number of squares counted, depending on the type of graph paper used. Paper with a grid size of approximately 1 cm works well.)

4. Have each student record the number of particles he or she counted in the appropriate place on the “Make a Dust Catcher” sheet (if you have made a copy for each student), or have students write the number in their journals or notebooks.

5. If you have one or more microscopes available, help students to examine their grids under higher magnification. You may want to trim the construction paper around the graph paper square to help it fit under the microscope.

6. Ask, What kinds of particles did you capture? Students are likely to find small hairs, tiny pieces of ash, crumbs, and bits of thread or lint. With the aid of microscopes, students also may see pollen grains, pieces of molds, and very small insect parts. Have them draw some of the particles they have observed.

7. For further discussion, refer students to the various sources of household dust pictured on the front cover of the Air unit’s Explorations magazine.

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Session 3: Graphing results

1. Conduct a brief survey of the values that students obtained for their dust counts. Create a chart on the board similar to the one on the right, taking into consideration the range of counts reported by the students.

2. Help each student place a dot or “sticky note,” labeled with the type of room tested, on the appropriate place on the graph.

3. Discuss the survey results with the class. Ask students to identify areas in their homes that have more or less dust. Also ask, Did different kinds of dust collect on dust catchers in different rooms? Talk about ways in which dust can be reduced or eliminated.

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Extensions

• Older students may enjoy making two or more dust catchers each, so that they can compare the number and kinds of particles captured in different rooms of their homes, or between indoors and outdoors.

• Young students may prefer making the dust catchers as a class project and positioning catchers in different places in the classroom.

• If anyone in the class has allergies to dust or any other substances, invite them to share their experiences with the rest of the class.

Handouts and Downloads