Lab: Measuring Air Pollution Using Gastec (From: Car Exhaust Analysis, Gastec Corporation, 2011)
(28 pts)
Name_________________________
Date__________________________
Period________________________
Objective:
To measure the ozone, carbon monoxide, and ozone produced by different cars.
Background:
The Clean Air Act defines EPA’s role in monitoring and protecting the nation’s air quality and the
stratospheric ozone layer. Since its passage 40 years ago, EPA has been required to set standards for air
pollutants and to permit discharges into the air. The EPA sets National Ambient Air Quality Standards
for six pollutants, called the criteria pollutants. These are: ozone, particulate matter, carbon monoxide,
nitrogen oxides, sulfur dioxide, and lead. Due to concerns about climate change, the Supreme Court
determined in 2007 that EPA should regulate carbon dioxide emissions. EPA has recently begun to
regulate carbon dioxide. In this lab, we will measure concentrations of three of these gases: ozone,
carbon monoxide, and carbon dioxide.
Ozone, O3, is “good up high, bad nearby”. Stratospheric ozone is responsible for protecting us
from UV A and UVB radiation, which can cause sunburn, skin cancer, cataracts, immune system damage,
plant damage, and phytoplankton damage. It can be depleted by gases like CFC’s (formerly in spray cans
and refrigerants), halons (fire retardants), N2O (fertilizers), HCFC’s (replacements for CFC’s used as
propellants and refrigerants), carbon tetrachloride (cleaners), and methyl bromide (pesticides). The
Montreal Protocol (1987) phased out CFC’s and is currently being employed to phase-out of HCFC’s. The
ozone that we will measure is tropospheric ozone, or “bad” ozone. This is formed by the reaction:
NOx + VOC’s + sunlight → O3 + other smog ingredients like PAN’s
Tropospheric ozone is a secondary pollutant, formed from other chemicals and sunlight in the
atmosphere. It is a strong oxidant. In humans, it causes coughing, chest pain, throat irritation, and
congestion. It can irritate asthma, emphysema, and bronchitis. When 0.1 ppm of ozone is inhaled for
two hours, the lung capacity can decrease by 20%. When 1 ppm is inhaled for six hours, it causes
headaches or bronchitis. When rats were exposed to 10 ppm, they suffered pulmonary edema and
died, indicating that ozone is quite toxic.
Carbon monoxide, CO, is a colorless, odorless, highly toxic gas produced by incomplete
combustion of carbon-containing materials. It is given off by industrial burning, some stoves, cigarette
smoke, and motor vehicles. Carbon monoxide interferes with the hemoglobin’s oxygen-carrying ability,
so cells become deprived of oxygen. Symptoms of carbon monoxide poisoning include headache,
dizziness, loss of judgment, nausea, heart problems, and potentially death.
Carbon dioxide, CO2, is a carbon-cycle gas naturally present in the atmosphere is small
concentrations. It is naturally added to the atmosphere by aerobic respiration, volcanic activity, hot
springs, geysers, and dissolving carbonate rock. It is removed from the atmosphere by photosynthesis
and by ocean organisms like coral, some algae, and mollusks. The chief anthropogenic source of carbon
dioxide is burning fossil fuels. Environmental scientists have been concerned because carbon dioxide
has been increasing at an increased rate since the industrial revolution. Since carbon dioxide is a
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Lab: Measuring Air Pollution Using Gastec (From: Car Exhaust Analysis, Gastec Corporation, 2011)
(28 pts)
powerful greenhouse gas, it has caused the average temperature of the earth to warm and has been
linked to ocean acidification. Under a Supreme Court ruling in 2007, EPA has begun to regulate carbon
dioxide under the clean air act.
Materials:
 Gastec sampling tube
 Carbon dioxide tubes 2EH
 Carbon monoxide tubes 1EL
 Ozone tubes 18EL
 Nitrogen Oxide Tube 11 EL
 Old newspaper
 Plastic garbage bags (~10 gal)
 Sharpie
 Rubber band or twist tie
 Tape (1 poll)
 Scissors (1 pr)
 Automobiles to test
Procedure:
Before starting, propose a hypothesis as to what differences you might expect to see. (2 pts)
1. Prepare the plastic bag for collecting the samples:
a. Cut a 2-3 mm hole toward the bottom on the bag. Using a marker, make a circle around the
hole so you can find it when you need it.
b. Place a small piece of tape over the hole and make sure it is secure. Fold the end of the tape
on itself to create a small tab. (This will make it easier to pull back each time you perform a test
on your sample.
2. Prepare the pump to collect samples:
a. Make sure the pump handle is pushed into the chamber.
b. Break off the tip of both ends of the carbon dioxide tube and place a pink rubber tip on the
end marked “G”.
c. Place the other end of the tube securely in the yellow Gastec pump with the arrow pointing
toward you.
3. Collect the exhaust sample:
a. Wrap the outside of the tailpipe with newspaper without blocking the exhaust.
b. Compress the bag to remove all the air from it and make sure the sampling hole is secure
before collecting the sample.
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Lab: Measuring Air Pollution Using Gastec (From: Car Exhaust Analysis, Gastec Corporation, 2011)
(28 pts)
c. Hold the plastic bag around the newspaper that is wrapped around the tailpipe.
d. Have someone start the car while another person is ready to collect the sample of exhaust
and twist the bag closed once it fills with car exhaust. (This happens very quickly so review steps
before performing the test.)
e. Secure the rubber band or twist tie around the top of the bag so you are able to test the
sample for three different gases carbon monoxide, carbon dioxide, and ozone.
4. Test the Sample: Carefully pull back the tape covering the sampling hole and insert the carbon
dioxide tube tester into the bag and pull the pump handle until you hear a click. Wait for 1 minute,
keeping the tube in the bag for at least one minute. (See the diagrams on the measurement sheet for
details.)
5. Collect the data: Write down the data on the table, indicating the number associated with the color
change. This represents the % of the particular gas.
6. Repeat Steps 1-5 for carbon monoxide, nitrogen oxide, and ozone gases.
7. Leave the car running 5 minutes. Using a different bag, repeat steps 1-5 for all three gases.
CAUTION: The tailpipe can get hot after running 5 minutes. DO NOT TOUCH THE TAILPIPE WITH YOUR
BARE HANDS AND DO NOT BREATHE THE FUMES FROM THE AUTOMOBILE.
Results:
Below are the results collected in the experiments: (12 pts)
Car 1:
Car 2:
Gas
Immediate
5 minutes
Immediate
5 minutes
Carbon
dioxide
Carbon
monoxide
Ozone
Car 3:
Immediate
5 minutes
Nitrogen
Oxide
Make a graph of the data. (5 pts)
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Lab: Measuring Air Pollution Using Gastec (From: Car Exhaust Analysis, Gastec Corporation, 2011)
(28 pts)
Questions/Conclusions:
1. Which target gas was highest at start up? (1 pt)______________________________
2. Which target gas was highest after 5 minutes?(1 pt) _______________________________
3. Was there any difference between the two vehicles tested? If so, what was the difference? (2 pts)
4. Which target gas showed the greatest change over 5 minutes? (1 pt) ________________________
Propose a hypothesis as to why this might be true. (1 pt)
5. What scientific, or social, or technological concerns or opportunities could/should be addressed
based on your findings? (1 pt)
6. Was your hypothesis met? Explain. (1 pt)
7. What experiment would you want to try next? (1 pt)
8. Would you expect to find large amounts of tropospheric ozone in your sample? Why or why not?
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