| .
. |
Air
Quality Objectives:
To
meet an Earth Science requirement of the California Science
Content Standard- "Structure and Composition of the Atmosphere."
Students
will:
- Understand
the thermal structure and chemical composition of the
atmosphere.
- Understand
how air pollution affects both humans and the landscape.
-
Define and collect particulate matter from air in test
areas around the school, analyze and draw conclusions
about airborne particulate pollutants.
Background:
Air
pollution is any visible or invisible particle or gas found
in the air adversely affecting health and welfare. Air pollutants
are produced by many natural sources such as volcanoes,
decaying organic materials, forest fires, oceans, lightning,
plants, and animals. In most cases, natural air pollution
emissions exceed those that are human-caused. However, natural
air pollution is usually widely dispersed, short term, and
less toxic than human-caused pollution. During the last
century human-caused air pollution has become a major concern.
Urban areas, agribusiness, and industry are all contributors
to air pollution problems. Ozone, nitrogen dioxide, sulfur
dioxide, carbon monoxide, and particulate matter are pollutants
of greatest concern. Resources that can be affected by air
pollution include visibility, flora, fauna, soils, surface
waters, odor, and cultural/archaeological/historical structures
and objects.
People
often believe that when they visit non-urban national parks
and Wilderness, they are leaving air pollution concerns
behind. Nothing could be further from the truth. National
Parks and Wilderness areas are affected by air pollution
concerns such as ozone impacts, acid deposition, and visibility
impairment. Not only can on-site pollution sources affect
air quality, but also pollution from upwind sources can
be transported great distances and contribute to air pollution
in Wilderness. Wilderness can experience pollutant levels
as high as those in upwind urban areas. Power plants, incinerators,
campfires, and vehicles are conspicuous sources of air pollution;
less obvious sources are oil and gas drilling activities,
gas stations, and landfills, among others.
Many
types of legislation give public land management agencies
the authority and responsibility to protect resources on
their lands from air pollution. Some of the strongest legislation
for air quality protection is found in the Wilderness Act
and the Clean Air Act. There are six federal criteria air
pollutants for which national ambient air quality standards
have been established. The federal criteria air pollutants
are carbon monoxide, lead, nitrogen dioxide, ozone, particulate
matter, and sulfur dioxide. The Clean Air Act designated
all international parks; national parks over 6,000 acres
in size, and national Wildernesses and memorial parks over
5,000 acres in size (in existence as of August 7, 1977)
as Class I areas. These areas are afforded the greatest
degree of air quality protection.
Activity:
Air Strips
Location:
classroom
and school
Duration:
2
class periods, 1 week apart
Materials:
-
2" x 10" strips of poster board with short piece of string
tied to one end
-
Clear tape 2" wide
- Low
power dissecting microscope or magnifying lenses.
Procedure:
Setting
the Stage for the Students
Our
atmosphere is almost completely made up of invisible gaseous
substances. Most major air pollutants are also invisible
gaseous substances although large amounts of them concentrated
in areas such as cities can be seen as smog. However, particulate
matter is easily visible, especially when the surfaces of
buildings and other structures have been exposed to it for
long periods of time or when it is present in large amounts,
such as smoke stacks from factories or industrial sites.
Particulate matter is made up of tiny particles of solid
matter and/or droplets of liquid.
Natural
particulate matter tends to be less of a problem to human
health and the general well being of the environment than,
that which is human-caused. Natural sources include volcanic
ash, pollen, and dust blown about by the wind.
Coal
and oil burned by power plants and industries and diesel
fuel burned by many vehicles are the chief sources of human-caused
particulate pollutants, but not all-important sources are
large-scale. The use of wood in fireplaces and wood-burning
stoves also produces significant
amounts of particulate matter in localized areas, although
the total amounts are much smaller than those from vehicles,
power plants, and industries.
Particulate
air pollutants can be harmful to plant and animal life when
the pollutants are absorbed. Particulate pollutants also
cause discoloration of buildings and other structures; this
is unsightly and expensive to clean up. Because it can have
harmful and serious effects, particulate matter is one of
the six criteria pollutants, a pollutant for which the government
has established laws and air quality standards.
|
.. |
Part
A: Construction of Air Strips
1.
Ask students how we know air pollution exists. Are air pollutants
visible? Invisible? Have students give examples of visible
air pollutants (smoke, dust, smog, and pollen). Define particulate
matter for the students. Particulate matter (PM) is defined
as a solid matter or liquid droplets suspended in the air.
PM that is less than 10 micrometers in aerodynamic diameter
(1/100th the width of human hair) is called PM10 (also called
coarse particles). PM of less than 2.5 micrometers in aerodynamic
diameter is called PM25 (also called fine particles or aerosols).
PM10 is a criteria pollutant. Share with students the "Setting
the Stage for the Students" information.
2.
Provide materials to make the airstrips and have students
follow the directions on the sheet. Make an airstrip for
yourself. Use this strip to show the students how their
finished products should look, then use it as a control
for Part C for comparison with the test strips exposed to
the air for one week. NOTE: Each student should make at
least one airstrip, more if there is time.
3.
(OPTIONAL) have students measure the mass (weight) of the
airstrips (including the control strip) as accurately as
possible on a balance. If you choose to do this step, explain
that the mass of the strips will be measured again after
the week of exposure.
Directions
for Making Air Strip
1.
Using a ruler to measure, cut strips of  poster
board that are 2' x 10".
2.
Cut five holes, each about 1" (use a quarter as a guide).
3.
Tie a string through a small hole at one end. Use this string
to hang the strip in its location.
4.
Place a piece of clear wrapping tape over one side of the
strip so that all five holes are completely covered. Do
not touch the sticky side of the tape, which will collect
particulate matter from the air.
5.
Write on the top edges of the strip the date, location,
and your name.
6.
Now hang the strip by its string in your selected location
where other students cannot bother it.
Part
B: Location of Air Strips
1.
Have students hang the strips at different places around
the school, both inside and outside. Inside the school,
hang strips in the halls, cafeteria, bathrooms, shop, gym,
labs, and/or kitchen. Outside, hang strips in trees, along
main walks, and at all entrances to the school. Give each
student tape to secure the airstrip's string to a stable
surface at the selected sites. The airstrips should be able
to move freely without bumping other surfaces.
NOTE:
All airstrips should be carefully labeled with date, location,
and student's name.
2.
After one week, have students collect the strips. Tell them
to be careful not to touch the sticky side of the tape.
Part
C: Analysis of Air Strips
1.
Have students visually compare the control airstrip to the
airstrips used to collect particulate matter.
2. (OPTIONAL) Have each student measure the mass of his/her
strip and compare it to the mass of the air strip before
the collection of particulate matter and to the mass of
the control strip before and after the experiment
3.
Distribute magnifying glasses and have the students try
to identify as many particles on the tape as possible. Dust,
ash, soot, and /or particles may be present. Depending upon
the time of year, pollen may also have been collected
(OPTIONAL: You may choose to have students use dissecting
microscopes instead of or in addition to magnifying glasses).
4.
Ask students to draw conclusions about the particulate air
pollutants in the test area. Are there differences in the
particles based on where the airstrips were placed?
5.
Have each student develop a chart or graphs using the information
gathered by the class and write a summary paragraph about
the activity.
Extension:
1.
Place air strips in a variety of other places for a week:
homes, churches, stores, urban and rural areas, factories,
car bumpers, high atop a roof, in a basement. Have student's
compare the particulates collected from the different locations.
2.
Post new strips daily and compare them to determine if the
day of the week makes a difference in the amount of particulate
matter collected. Have students consider such possible factors
as the weather, wind direction and force, and industrial
or business schedules for the days examined (this can lead
to discussion of particulate matter pollution sources).
NOTE:
If the students are examining daily influences, they need
to keep daily records when they hand in the airstrips.
Additional
Web Resources:
|
|
