2: How Can We Measure Ozone?

Overview

Families will discuss what they discovered about their exposure to ozone over the course of the past week as well as what they found out about health effects. Then, each family will build its own ozone-measuring instrument (ozonometer), and learn how to use it. Families will measure ozone levels over the course of the week using the ozonometer and will keep track of changes they are trying to make in some of the things they do that cause ozone pollution.

Advance Preparation

• Make copies of the handout, Building an Ozonometer:Stepsand
  Building an Ozonometer: Steps, one per family.
• Make copies of the sheet, Ozonometer Data Collection Sheet, one per person.
• Make an ozonometer ahead of time so you'll be familiar with the process and have a completed one to use as a model for participants.

Materials you need to provide

• Master of the handouts, Building an Ozonometer: Materials and
  Building an Ozonometer: Steps.
• Master of the sheet, Ozonometer Data Collection Sheet.
• Ozonometer kits, one per family.
• One completed ozonometer, for demonstration purposes.

Activities

1. What did you find out about your exposure to ozone and the associated health effects?

(Ask people to have their ECO Badge Data Collection sheets and their Ozone Health Effects and Recommendations charts on hand for the discussion.)

• Ask the participants to share what they found out, over the course of the week, about the ozone levels they were exposed to.
  • What was the highest ozone concentration you were exposed to when wearing the ECO Badge? Were you active or at rest? What are the possible health effects associated with the amount of ozone you were exposed to?
  • What was the lowest ozone concentration you were exposed to?
  • Were there other findings that were interesting?
  • What did it feel like to wear the badge, to be aware of your exposure to ozone, and to know about the possible health effects?
• Ask participants what they found out about how people could help to protect themselves from the health effects of ozone. People might want to take a look at their Ozone Health Effects and Recommendations charts in this discussion.

2. Building our own ozone-measuring instrument -- an ozonometer

• Explain to the group that there is another way to measure the amount of ozone present in our air, using the fact that ozone cracks untreated, natural rubber. Show the group an assembled ozonometer.
• Depending on time available and interests of participants, you may want to explain how the ozonometer works. Or, you might want to ask people first to take a look at the ozonometer, and try to figure out how it works.

Note to Program Leader: How does the ozonometer work? A loop of rubber thread is stretched around the bearing. One side of the rubber loop is protected from ozone by the jacket of blotter paper. The other side of the rubber loop is exposed to any ozone in the air. Since the rubber is untreated, it cracks when exposed to ozone. As it cracks, the unprotected side of the rubber loop lengthens, and the bearing turns. The turning of the bearing moves the pointer along the printed scale. The more ozone in the air, the faster the pointer turns. By measuring how far the pointer moves in a fixed amount of time (an hour), we can use the ozonometer to measure the concentration of ozone in the air.

Use the chart on the ozonometer to convert the pointer reading to the ozone concentration. For example, if the pointer lies at 20 degrees after one hour, the corresponding ozone concentration is 100 parts per billion.

• Distribute the activity sheet, Building an Ozonometer:Materials and
  Building an Ozonometer: Steps, one per person and the ozonometer kits, one per family.
• Now families start building their ozonometers. Let the group know that you will be circulating to provide any help they might want. Also, suggest that families act as resources to one another as they work on the different steps in the construction of their ozonometer. Have a completed ozonometer available for families to use as a reference.

3. Preparing for home data collection with the ozonometers

• Give each person one copy of the Ozonometer Data Collection Sheet.
• Go over the directions on the activity sheet which explain how to use the ozonometer. Have participants refer to the ozonometer they just built and/or use a demonstration ozonometer to illustrate each step.
• Explain that we're going to collect data on ozone concentrations and weather conditions. Scientists have been studying ozone for a number of years. They have found, for example, that ozone concentrations tend to be highest on sunny, hot, still days. They have explored questions such as the following as well:
  • Is there a difference in ozone concentrations on sunny days vs. cloudy days?
  • On a sunny day, at what time of day is the - ozone concentration highest: morning, afternoon, or evening?
  • What happens to the ozone concentration if there are three hot, sunny days in a row?

Over the course of the week you can use the ozonometer and fill out your ozonometer data collection sheets to explore ozone levels in your area. You might want to explore one or more of the above questions. You might also want to come up with your own question(s) to explore.

Note to Program Leader: Participants might be able to see relationships between weather and ozone in their data. However, since the relationships between weather and ozone are complicated -- and since participants are looking at only a few aspects of weather over a short amount of time -- participants might not be able to answer their questions definitively from the data they collect. The main goal of this activity is to get some hands-on experience in measuring ozone. Participants shouldn't be surprised if their data don't yield definitive answers to their questions.

• Review the data collection sheet which explains how to record ozone and weather data. Suggest that people collect data on ozone and on weather conditions on at least three different days.
• Remind people that they should use the chart on the ozonometer to determine what the ozone concentration is.
• Have families practice putting the rubber thread on the ozonometer.
• If applicable, let people know that some of the group's data will be sent to the local TV station weather forecaster.

4. Preparing for other home activities

• Remind the group to:
  • try to modify a few of their behaviors and keep track of the modifications. Ask people to bring their family's copy of the pamphlet, 25 Ways You Can Clean The Air, and their own copy of the sheet, Changes in Behavior with them to the next session.
  • collect data on ozone (using the ozonometer) and on weather conditions on at least three different days, if possible.
  • bring their Ozonometer Data Collection Sheets back to the next session.