Sampling Airborne Particles:  3 Methods

 

Particles Strand Protocol

 

To evaluate particles as small as 10 to 100 microns in size (a micron is one millionth of a meter), you need to build particle collectors that will capture airborne particles and install them in different locations.

 

A. Flat Index Card Jelly Particle Collectors

These particle collectors collect particles on exposed petroleum jelly. They are easier to construct than the flat tape collectors, but the samples are harder to analyze. Flat jelly particle collectors are most helpful if you only need to determine the quantity of particles at different locations.

 

Materials

petroleum jelly

white index cards

scissors

string

 

Constructing Flat Jelly Particle Collectors

1 For each particle collector, lay an index card on the table with the blank side up.

2 Using a pen, draw a square—approximately 3 cm to a side—on each index card.

3 Spread petroleum jelly across the square. Try to cover the square evenly.

4 If you are going to hang the collector, punch a small hole at one end and run string through it.

 

Placing Flat Jelly Particle Collectors

Place collectors wherever you wish to gather data, and label each with its location to simplify gathering and analysis later on. Placement of your particle collectors will depend primarily on what you are interested in learning or the nature of your research question.

 

Analyzing Your Collected Particles

After approximately a week, gather your particle collectors. Examine the petroleum jelly with the naked eye and estimate the apparent density of visible particles.

¥ How dark does the jelly appear?

¥ Can you arrange the collectors from light to dark?

¥ Can you see any patterns? Can you use the collectors to

map an area? Can you see any patterns then?

 

 

B. Flat TAPE Particle Collectors

 

Materials

Clear adhesive tape

Construction paper

Scissors

Paper clips

Strings

Microscopes

Blank transparencies

Ruler

Fine point transparency marker

 

Constructing Flat Tape Particle Collectors

 

1. For each particle collector, cut two pieces of paper 8 cm in size.

2. Cut four aligned circles in one piece.

3. Touching the sticky side of the tape as little as possible, place strips of the tape on this piece so that the sticky side is exposed through all four holes.

4. Place enough strips so that the tape covers each hole completely, but make sure the strips are adjacent and do not overlap.

5. Secure the other piece with paper clips to the back of the first piece, making sure the sticky side of the adhesive tape remains exposed.

6. If you are going to hang the collector, punch a small hole at one end and run string through it.

 

Placing Flat Particle Collectors

Place collectors wherever you wish to gather data, and label each with its location to simplify gathering and analysis later on.  Placement of your particle collectors will depend primarily on what you are interested in learning or the nature of your research question.  Where do you want to collect data and why do you want to collect at those locations?

Some locations that may be of interest include your classroom, other classrooms, hallways, metal or woodworking shops, industrial areas, roads or highways, and your study site.

 

Analyzing Your Collected Particles

 

First, to help you count the particles, prepare a grid on a transparency.  Draw the lines 5 mm apart so that each cell is a square 5 mm by 5mm.

 

After about a week, gather your particle collectors and remove the back piece of paper from each.  Lay each collector on the table with the sticky side facing up.  Place a transparency grid over it.  Examine each collector under the microscope.  You should be able to see particles stuck to the tape.

 

Count the number of particles visible within one cell and record the number. Perform this procedure for at least four randomly selected cells within each of the four round windows for each collector. Calculate the average reading for each collector. Can you calculate an overall average particle count per square millimeter in the air?

 

Categorize the particles within one cell. A microscope enables you to see both organic and inorganic particles. Organic materials may include rug dust, human skin, pollen, and dirtÕs organic components. Inorganic materials may include chalk dust, paint chips, tire treads, clothing fibers, and dirtÕs inorganic components. Particles occur in various shapes: triangular, square, round, round with appendages, and star. Can you categorize the particles you collected? What seems to be the most common shape?

 

Estimate the particle density of each round window on the particle collector by examining the tape with your naked eye. How dark does the tape appear? How do the four round windows in a collector compare with one another? Can you arrange the collectors from light to dark? Can you see any patterns?

 

C. Directional Tape Particle Collectors

These particle collectors collect particles from different directions on different parts of an exposed adhesive tape. The tape should be clear, because you will probably want to observe the collected particles with a microscope. The idea is to identify sources of various types of particles, including the most commonly-occuring particle type.

Materials

cans, jars, or other

cylindrical containers

white paper

clear adhesive tape

board (optional)

screw (optional)

compass

blank transparencies

ruler

fine-point transparency

 

Constructing Directional Tape Particle Collectors

Wrap white paper around the outside of a bottle or jar. Wrap sticky tape around the paper, making sure that the sticky side of the tape faces outward. Secure the bottle on your collection site. You may want to secure your collector to a board or other surface so that it is stable.

 

Placing Directional Tape Particle Collectors

Place collectors wherever you wish to gather data. Label each with its location and orientation (using the compass) to simplify gathering and analysis later on. Placement of your particle collectors will depend primarily on what you are interested in learning or the nature of your research question.

 

Analyzing Your Collected Particles

After approximately a week, gather your particle collectors. Carefully analyze the tape. Are the particles uniformly distributed around the container? Are they concentrated on one side? What can these particles tell you about their sources? If the collectors were used

outdoors, what can they tell you about prevailing wind directions? Is there a correlation between wind direction and the number of particles collected?

 

To help you count the particles, prepare a grid on a transparency. Draw the lines 5 millimeters apart so that each cell is 5 mm by 5 mm. (Your grid should be larger than your particle-covered tape.)

 

 

Carefully remove the tape from around the container, place a transparency grid over it, and analyze the particles under a microscope as explained for the Flat Tape Particle Collector. Can you see differences in the types of particles collected from different directions? Can you identify particle sources?