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U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
September 1974
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RAPS: a new
approach to air pollution
T"1 he largest, most comprehensive investigation of
air pollution ever undertaken is now in prog-
ress—and it is being conducted here in the St.
Louis metropolitan area.
The project is the Regional Air Pollution Study
or, more simply, RAPS. It is being conducted by
the U.S. Environmental Protection Agency (EPA)
to develop models for testing air quality manage-
ment techniques that will help curb air pollution
in greater St. Louis. That alone would be enough
to merit attention, but there is more. RAPS is
also a major pilot study; what is learned here will
be applied in other cities and other nations.
Because RAPS and its results are important to
you, as well as to your brothers and sisters here
and around the world, this leaflet has been pre-
pared so that you will know what is happening,
why it is happening, and what it will mean.
The problem
Air pollution is recognized as a real problem
that poses a very real threat to our health and our
environment. The evidence is extensive: scientific
studies have been made, documented evidence
compiled, and brought before Federal, State and
local governments. Virtually everyone has come
to realize that there are dangers, real and potential,
from air pollution.
But at the same time, there is a feeling, par-
ticularly among young people like yourself, that
this public awareness has not been followed by
enough action. If the problem is immediate, they
maintain, the solutions should be too. They feel
that little progress is being made against this
threat to health and the environment.
It may seem that way but it is not so. Far more
is being done than you might imagine. EPA and
State and local government environmental agen-
cies have long been active enforcing pollution
control laws passed by Congress.
So why does the problem continue?
One stumbling block to achieving clean air
is resolving situations which involve conflicts and
compromises between enforcing agencies and
polluters, large and small. How do we take cor-
rective action without getting harmful side effects?
For instance, we could clean up the air by elimi-
nating the major sources of pollution—cars,
trucks, trains, planes and industry. But this is not
practical. What would happen if we could not
produce the food, clothing and other goods we
need for life itself? We must seek to meet air
quality standards, keeping pollution at a low
enough level to protect the public health and
welfare and at the same time maintain our quality
of living. To do this, we must obtain information
as complete and as accurate as possible so that
we can better evaluate what is the proper action
to take.
Is that what RAPS will do?
That's precisely what RAPS will do. It will
give us a more detailed measurement of air pollu-
tion than we have ever had before. RAPS will
feed those measurements into computers to ob-
tain answers and allow predictions to be made
under various pollution conditions. And RAPS
will test a variety of methods for controlling pollu-
tion. It will enable us to check alternative strate-
gies, and determine what really works best to
bring pollution under control.
How will RAPS change things?
RAPS will greatly enlarge on what we currently
know about how much pollution is in the air and
how much we can tolerate. RAPS will tell us
about the air above each part of our metropolitan
region. It will reveal what pollutants exist over
each area, the direction in which they are moving,
and what chemical changes occur as pollutants
mix and as they are exposed to sunlight and other
elements. With such detailed measurements and
through computer analysis, scientists hope to
develop mathematical models that will guide us
toward accurate and effective control procedures.
In short, RAPS is designed to provide the in-
formation which will be the basis for reasonable
and effective air pollution controls—and while
gathering the information it will test which air
pollution control strategies work best.
How is RAPS organized?
RAPS is a $22 million, 5-year scientific proj-
ect funded and conducted by EPA. The Rockwell
International Corporation is the prune contractor
and several subcontractors from the St. Louis
area will handle specific jobs such as equipment
installation or data management. Numerous local,
State, and Federal agencies are cooperating in
the project, and qualified local college students are
participating in some of the field studies and meas-
urements. When it is completed RAPS will make
it easier for EPA to control air pollution. For you
it will mean cleaner air to breathe.
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100R74O11
Why St. Louis?
It's a good question. Your city doesn't have
the cleanest air in the Nation, but neither does it
have the dirtiest. So why was it selected? This
area was chosen for several reasons.
Of 33 American cities, St. Louis was found to
be similar to the other 32. Your city has a climate
that is most like the majority of other U.S. urban
areas. It has a wide variety of emissions as deter-
mined by fuels used, industrial production proc-
esses and pollution mix. It is also reasonably
isolated from the pollution of other major sources
outside the area. It is far from the oceans and
Great Lakes, hills and mountains, all of which
can have an effect on air pollution. And the
greater St. Louis region is also large enough to
conduct this study.
Finally, St. Louis has had previous air pollu-
tion studies and the continuing work of existing
environmental agencies provides available back-
ground information, particularly in the area of
meteorology, emissions and air quality.
How will RAPS be carried out?
In order to properly study the region, covering
roughly a 25-mile radius from the Gateway Arch,
a network of 25 remote air monitoring stations
has been established. Stations will also be located
in the greater St. Louis area in both Missouri
and Illinois. (See map.) In addition, this network
will be supplemented by 10 monitoring stations
opsrated by local agencies.
Each station contains analytical equipment to
measure pollutants and meteorological conditions,
plus a minicomputer to acquire the data and
transmit information to a central headquarters.
Information will also be gathered by mobile
vans and aircraft. The highly advanced electronics
equipment used in the monitoring stations also
will be contained in mobile units. On the ground
we will be monitoring the hourly emission rates
of smokestacks and calculating emission rates
through plant fuel consumption or plant process
schedules. Helicopters and fixed-wing aircraft will
sample the air. Photography and radar will be
used to study air pollution rising up from the
street and river traffic and from the railroads. We
are even going to check the effects aircraft may
have on the problem, including that of our sur-
veillance aircraft.
This is what RAPS is really all about, collecting
and evaluating information needed to test our
clean air strategies.
So what in particular will RAPS be
involved with?
A great many things. The investigation will be
conducted across the wide spectrum of the physi-
cal sciences and will include some of the social
sciences as well: meteorology, atmospheric chem-
istry, aerosol physics, applied mathematics and
even health and welfare studies and economic
analysis. All will be employed to gather and
evaluate the information about air pollution.
Information gathered on a continuous basis will
be available for automatic retrieval. Scientists will
use it to develop mathematical models which de-
scribe air pollution under virtually any circum-
stances. Proposed methods for controlling pollu-
tion can be tested against the models. Scientists
also expect to evaluate such new remote sensors
as lidar and acoustic sounders. Research for the
project is being conducted nationwide by a variety
of institutions. Locally, Washington University
is studying how gas pollutants change into par-
ticles in the air. Students and instructors at St.
Louis University and the University of Missouri
are looking into the relationship between pollution
and vegetation, i.e., how plants act as filters to
remove particles from the air.
The analysis and re-analysis will be done at
the central support facility located in Creve Coeur.
It houses both manual and automated data proc-
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THE SCENE AT ST. LOUIS:
Below, a lab technician inspects large plastic
bags that will be used for ah- samples taken
with the help of equipment (lower right) in
each of the 25 Regional Air Monitoring Sys-
tems (RAMS) throughout the greater St.
Louis area (far right). At middle right is
computer, built by Rockwell International,
that receives and stores data from the
RAMS. Weather maps, right, are important
aids in the RAPS program.
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essing equipment and is linked to the monitoring
stations that are scattered throughout the city via
telephone circuits. The support facility also has
offices and a laboratory for instrument mainte-
nance and repair.
We think RAPS is pretty important
So do a lot of other people. The information
gathered will not only be studied by your State
and local environmental agencies, but by those
of foreign governments as well. Under a protocol
agreement between the United States and the
Soviet Union, the two countries will study and
evaluate the data collected from RAPS—St. Louis
and a similar study now underway in the Soviet
city of Leningrad. During the next several years
representatives of Russia and other nations will
be visiting your city to observe the RAPS opera-
tion firsthand.
What can students do to help?
RAPS is truly a program for the people. Its
primary goal is to give you and your parents a
better life, one in which the air will be clean.
The most important thing you can do is to tell
your parents and your friends about RAPS. For
if RAPS is to be successful, we will need the
understanding and cooperation of St. Louis area
citizens. There will be some minor inconveniences.
The helicopter flights, for instance, will be noisy
because we need helicopters to handle the meas-
uring equipment. Those flights will be made
during February, August and November for the
next three years. If you help explain RAPS, you
will help people understand the need for those
nights.
RAPS also will involve measurements of emis-
sions from smokestacks at major industrial loca-
tions in ths area. These will involve the use of
laser beams, and new remote sensors to detect
pollution will be tested. For these parts of the
RAPS program, cooperation will be needed from
business and industrial leaders. If you help make
RAPS known in St. Louis, you will be helping
us to obtain that cooperation.
We hope you will agree that RAPS is important
to us all. If you would like to get further involved
in the type of work that RAPS will be concerned
with, here are several experiments for you to
try in your classroom. They all deal with air, and
are divided into intermediate and high school level.
Although these experiments are not as sophisti-
cated as those that will be conducted by _ the
RAPS program, they will give you a visual idea
of the pollution problems in St. Louis.
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Experiments
Reproduced from "Air Pollution Experiments for Junior
and Senior High School Science Classes" (Second Edition)
with permission of the Air Pollution Control Association,
Pittsburgh, Pa.
INTERMEDIATE—AIR
CONCEPT
Acid gases and aerosols are prime ingredients of
urban air pollution. These gases may damage
plants, corrode metals, crumble stone, and in
heavy concentration, they can make men and
animals ill.
EQUIPMENT
A large funnel, an air pump or aspirator (most
pet shops sell air pumps), filter papers, one for
each exposure site, large enough to cover the
large end of the funnel, a piece of wire screen
the same size. Tape to hold filter paper on funnel,
1 ounce of 0.01M sodium bicarbonate solution, 1
ounce of glycerin, 2 or 3 ounces of a dilute solu-
tion of 10 percent hydrochloric acid in a beaker,
3 eye-dropper bottles, 2 or 3 feet of rubber or
glass tubing, chart and graph. (See Figure 1 and
Figure la.)
PROCEDURE
Cut filter paper big enough to fit over the large
opening of the funnel with a Vi-inch overlap.
Tape it on. Add a drop of glycerin to the center
of the paper. Add a drop of the indicator solution
to the center of the paper. More drops may be
necessary if the color is not apparent. Add a drop
of sodium bicarbonate solution to the center of
the paper.
[NOTE: Support the filter paper with a piece of
wire screen cut to fit over the opening of the
funnel if the moistened paper cannot withstand
the flow of air through it without rupturing. Place
the screen on the funnel, then place the paper
over it. Secure both with tape or a rubber band.]
Attach the tubing to the small end of the funnel
and to the air pump. Start the air pump and the
timer. Do a preliminary test, drawing air from
above the open bottle of dilute hydrochloric acid.
Stop the pump when a red color is visible.
Test some air: Take samples from a chemistry
laboratory, outdoors, hi a kitchen, from exhaled
breath. Record the results on a chart and bar
graph to illustrate the presence of acid gases at
the test site. (See Figure la.)>Record on the chart
the site location, the time you started taking the
air sample, and the time the treated filter paper
began to react with the gases. Show the elapsed
time figures in the form of a bar graph. Then you
will have a complete picture of the acid gas con-
centrations encountered in the test.
Figure 1
Air Assembly
Figure la
Air Graph
STARING STOPPING ELAPSED TIME (Show in form of bar graph)
SITE TIME TIME
A
B
C
D
E
F
G
H
0 5 10 15 20 25 30 35 40 45 *
(MINUTES)
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HIGH SCHOOL—AIR
CONCEPT
This experiment demonstrates that the air in
which we live and which we breathe is not always
as clean as it appears to be.
EQUIPMENT
Small vacuum pump or water aspirator having an
air volume capacity of approximately % cubic
foot per minute. Two pieces of 28-mm (outside
diameter) glass tubing 50- to 75-mm long, with
1.2-mm wall thickness (be sure glass tubing is
cut square and the ends are fire polished to avoid
cut fingers). Window screen disc cut 28-mm in
diameter, two rubber stoppers to fit glass tubing.
Each stopper to have an 8-mm hole in center.
Two 75-mm pieces of 8-mm outside diameter glass
tubing. Whatmann #41 filter paper 28-mm diam-
eter discs, rubber band, 1-inch wide, to fit snugly
around 28-mm tubing, or 1-inch masking tape,
burette stand with a 3-finger clamp, plastic (Tygon
or Nalgon) or rubber tubing to connect filter to
vacuum pump and to act as a probe to collect
outdoor air, flowmeter (rotameter) of appropriate
range, or a wet or dry gas meter if available. A
critical orifice of proper size may be used to
control air flow at the maximum rate desired.
Glass bottle (1-gal. capacity) fitted with 2-hole
rubber stopper containing one long and one short
piece of 8-mm glass tubing. The bottle should be
nested in a corrugated board box for safely.
ASSEMBLE APPARATUS
Set the screen on top of one piece of 28-mm
tubing (now called cylinder #1).
Place a filter paper disc on the screen.
Place the other piece of 28-mm tubing (cylinder
#2) on top of the filter paper, press the two cyl-
inders together and make an air-tight seal with
the rubber band or with masking tape.
Insert a small glass tube in a hole through each
rubber stopper. Place one stopper in the lower
end of cylinder #1 and the other stopper in the
upper end of cylinder #2. Mount the assembly
in the burette stand with cylinder #2 in the
upper position.
Using plastic or rubber tubing, connect cylinder
#1 to the lower tap on the rotameter or to the
inlet of other type of flow measuring device. Con-
nect the outlet of the rotameter or other flowmeter
to the inlet side (long glass tube) of the 1-gallon
bottle. (This bottle evens out any fluctuations due
to the vacuum pump. It is called a surge or buffer
bottle.)
Similarly connect the outlet tube from the surge
bottle to the inlet tap of the vacuum pump or
other source of vacuum.
Connect a long piece of plastic or rubber tubing
to the inlet end of cylinder #2, and pass the other
end through a window. The stem of the funnel
should be inserted in the tubing hanging outside.
The funnel should hang upside down to prevent
rain from entering the tubing.
PROCEDURE
Start the vacuum pump and record the time.
Measure and record the rate of air flow.
Allow air to pass through the filter for two hours
or as long as required to darken the filter paper
noticeably.
Measure and record the rate of air flow. Stop
the vacuum pump and record the time.
Dismantle and observe the soiling of the filter
paper.
If a photometer to measure transmittance of
light through ths soiled filter paper is available,
a quantitative evaluation of the amount of soiling
can be made.
QUANTITATIVE EVALUATION
Theory—The amount of discoloration on the
filter paper is approximately proportional to the
quantity of solid particles suspended in the air.
This makes it possible to relate the decrease in
light transmittance through the paper to the
amount of particles collected on it. The light
transmittance of the paper can be measured with
a photometer before and after filtering the air by
placing the clean filter disc and later, the exposed
filter disc against the photometer window and
noting the intensity of light transmitted in each
test.
From these measurements the optical density of
the soiled filter paper can be computed in COHS.
The COH is an abbreviation for Coefficient of
TVU.S. GOVERNMENT PRINTING OFFICE 1974: 624-971
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Haze and one COH unit represents an optical
density of 0.01. The optical density of the deposit
or soiling is the logarithm to the base 10 of the
ratio of the intensity of light transmitted through
the clean filter paper to the intensity of the light
transmitted through the soiled filter paper. In
terms of percentage, it can also be the ratio of
percent transmittance through the clean paper
(considered as 100%) to the percent transmit-
tance through the soiled paper.
Therefore,
I0 Iog10 100%
It
where,
I0 =
It =
%T =
%T
average light intensity transmitted
through clean filter paper,
light intensity transmitted through the
soiled paper, and
percent light transmitted through the
soiled paper when the light
transmittance through clean paper is
considered as 100%
Since Iog10 of 100 = 2.0, we have
O.D. = 2.0 - log %T
By definition, one COH unit equals an optical
density of 0.01. Thus, the number of COHS
represented by the actual O.D. found equals
O.D./0.01 = 100 X (2.0 — log %T).
COH unit measurements are usually expressed as
COHS per 1,000 linear feet of air passed through
the filter paper. The concept of linear flow, upon
which the expression COHS per 1,000 feet is
based, considers that through each point on the
surface of the filter a long stream of air passes
leaving its load of dirt particles deposited. One
might think of the sample as a long column of
air the same diameter as the diameter of the
exposed filter paper and with a volume equal to
the measured volume of the air sample.
Computations
1. Volume of air = R2 — RI (for dry or wet gas
meter),
R2 = final reading in cubic feet
R! = original reading in cubic feet
or, volume of air
— ^ 1 "*" *' (for rotameter or critical orifice)
2
F! = initial flow rate in cubic feet per minute
F2 = final flow rate in cubic feet per minute
t = sampling time in minutes
Corrections for Temperature and Pressure
The value R2 — RI for the gas meter should be
corrected for temperature and pressure according
to the Charles' and Boyles' laws.
Each F value for the rotameter or orifice should
first be corrected to what it would be at the
standard temperature and pressure at which the
measuring device was calibrated:
2. Area = TT d2, where d is the inside diameter of
""4" the cylinder in feet
_ cm. in. ft.
Ft. = mm. X X X ^r—
mm. cm. in.
Volume
3. Linear feet of air = — = L
Area
4. COHS per 1000 feet
= (2.0 - log %T) X 100
L/1000
(2.0 - log %T) X 100 X 100
(2.0-log%T)Xl05
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