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Studying Ozone and Air Quality

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1 Studying Ozone and Air Quality
Steve Schneider Deborah Carlisle Goals : Provide students with project work that will educate them about air quality with O3 and CO2 (smog and emissions)

2 Measuring Ground-level Ozone
VOC’s + NOX + sunlight  O3 Motor vehicles are the single largest contributor to ground-level ozone. O3 levels above 120 ppb (by volume) are considered unhealthy. They can be generated by some electrical equipment or from photochemical reactions with smog:

3 Measuring Ground-level Ozone
O3 levels above 120 ppb are considered unhealthy. They can be generated by some electrical equipment or from photochemical reactions with smog: VOC’s + NOX + sunlight  O3 Motor vehicles are the single largest contributor to ground-level ozone. In this project we are adapting the relatively easy-to-make Schoenbein papers for classroom use, and using ADI to analyze the color changes quantitatively. Color chart allows for a general

4 Index values in ppb 1000ppb = 1ppm
*Crop last column (rt click – check Fx) – Omit and add #’s to USA slide

5 Useful Sites
Interesting data based on scattered data – based on site BUT local sources are very relevant and use strip to verify certain areas such as bus stops, Add Mass DEP

6 Commercial Papers: Ecobadge, Ozone badge
We were interested in using this to test air quality – started with commercial papers Lots of variability up to 50 +ppb Ozone solutions and Vistanomics

7 Findings: Commercial cards had significant variability and were expensive. Researched making Schoenbein papers Inexpensive and safe to make

8 Schoenbein Papers Ozone was discovered by C.F. Schoenbein in He developed an ozone-sensitive test paper that was widely used historically, and more recently in classrooms. The standard protocol for using the papers calls for an 8-hour exposure to the air out of direct sunlight. Various studies have shown a dependence on humidity, and there are a variety of recommendations for moistening the strips prior to exposure. Control low O high O3 exposure exposure They are relatively easy to make – takes some practice to get an even application of the chemical across the entire filter paper.

9 History Despite the method's early limitations, starting in the mid-1800s, more than 300 stations recorded ozone exposures in countries such as Austria, Australia, Belgium, England, France, Germany, Russia, and the United States. Using Schoenbein papers – Why were people concerned (in London) – develop a bit of history. Industrial Black smog of London 1852 thousands died of smog inhalaiton due to coal combustion

10 Learning Goals : Analyze different relative amounts of ozone found in various locations using test results. Understand that ozone is found near the earth’s surface (ground level) in the troposphere as well as the stratosphere. Understand that ozone test strips/Schoenbien paper detect ozone gas through a chemical reaction that is caused by ozone in the air. Use technology to more precisely analyze relative color changes obtained with ozone test strips. For students

11 Some Testing Ideas: Test for ozone at different times of day and look for patterns. When are ozone concentrations the highest? Test for ozone in various locations and see what areas are the highest. Look at the effects of wind patterns on ozone Students research and brainstorm where ozone might be found and what equipment/machines produce ozone For students

12 Making Schoenbein Papers
Refer to handout – I’ll do demonstrate Explain protocol – about 30 min.

13 Classroom Use Made Easier:
1. Test strips can be stored in a double plastic zip lock bag, until you are ready to read your results. 2. To look at results simply dip your exposed test strip in a beaker of water. You will see a visible color change. 3. Compare the relative colors to the control. 4. Use digital analysis to measure RGB values and compare between test strips. Edit Color chart allows for a general


15 Testing Ozone Levels Groups of 4 Select a test site Things to Consider
Avoid direct sunlight Free air circulation around your strip Run a control with your group Label an index card with date/time/location Time required to hang strips and test – 20 min.

16 Outdoor exposure Distribute teacher notes, and have them turn to pg 4 in handout “Use of Test Strips”

17 Carrying Out the Experiment:
Discuss experimental design in your groups to come up with a plan for testing Run tests (place test strips and control) Collect test strips and place in zip-lock baggies Return to lab and expose strips by dipping in water Photograph test strips Data Analysis and share results See – handout Outline this before you begin

18 Data Analysis

19 How do Ozone Test Strips
Work? Ozone is a strong oxidizer. It rapidly reacts with the iodide ion, I- in the KI salt applied to the filter paper. KI + H2O + O3  I2 + O2 + K+ I2 + I- + starch  I3- + starch Last step : I3- (linear)+ starch (helix) (Turns Blue) Combination of I3- and helix causes light reflection to be in the blue/violet range of visible spectrum


21 Schoenbein Papers Cntrl Cntrl 50 ppb – jpg 735

22 Comparing Test Strips 10,000 pixels

23 Find region on gray scale that is close to your strip

24 Calibration of Test Strips
Green wavelength here – rough idea If G value is below approx. 18 then ppb is greater than 140+


26 National Science Education Standards
Science as Inquiry: Grades 5-8 and 9-12 Ability to perform scientific inquiry, understanding about scientific inquiry Science and Technology: Grades 5-8 and 9-12 Understanding about science and technology Science in Personal & Social Perspectives: Grades 9-12 Environmental quality, changes in environments

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