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What's The Air Forecast?

Activity 8 (Elaborate): Smog City: How Weather Affects Air Quality

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Activity Overview

Activity Summary

This activity is based on the EPA’s air quality and weather simulation “Smog City 2”. After a brief introduction to the simulation, students explore how different variables centered around emissions, weather, and population affect air quality. This if followed by a discussion to summarize what they learned from the simulation.

Activity Objectives & Materials

Approximate Time: 45 minutes​


  • Students will understand how different weather conditions affect AQI

  • Students will understand how emissions from various sources and population affect AQI



  • Computer & projector

  • Student computers (highly recommended)


  • Save Smog City from Ozone!

Important Technology Note About This ActivitySmog City 2 uses Flash, which is not supported in newer browsers. You will need to click the option to allow Flash to run in your browser in order to launch Smog City. If this does not work, you may need to use a downloaded copy, so be sure to try the simulation out on student computers before using it with a class. You can download a copy of Smog City 2 by signing up here:

Standards Connection

DCI: ESS3.C – Human Impacts on Earth Systems

DCI: ESS2.D – Weather & Climate

SEP: Developing & Using Models

CCC: Patterns; Systems & System Models



Have students take out the visual glossary they created in Activity 2. Then have them describe today’s weather today using these scientific terms. Students may look up the details using computers (which will be used today) or from a handout/ projection of a current weather report.


1. Frame the Activity

Remind students that for this investigation they have taken on the role of meteorologists. So far in the investigation, they have been learning how to explain the weather. Now that they understand more about how weather and air pollution work, it is time for them to learn how to predict the air pollution so that they can keep people in the community safe from air pollution. To do this, they need to understand how weather affects air quality. Today they are going to use a computer simulation of a real city to see how weather affects air quality.

Step 1

2. Smog City 2

Display the Smog City simulation on a projector where all students can see it:












Show students how to launch the simulation, and briefly review the controls with them. Pass out the Save Smog City from Ozone! sheets and student computers. Then support students in following the directions on the handout and answering the questions.

Smog City front page.jpg

ModificationIdeally, students will do this activity on their own or in pairs using student computers. If computers are not available, the activity can be done together as a class using a projector.

DifferentiationPair students for the simulation in a way that allows more advanced students to support struggling students.

3. Smog City Summary Discussion

Lead a discussion with students on how different weather factors affect the level of pollution. Create an anchor chart based on students’ responses that you can leave up in the room (this will help with later activities in the module). As students answer, ask why they think this weather factor changes the AQI in the way it does. Make sure to leave room at the bottom to add other factors.

  • Sky condition/cloud cover: more clouds = lower AQI because there is less sunlight to generate ozone

  • Wind: more windy = lower AQI because the ozone is blown away

  • Inversion (optional): an inversion = higher AQI because pollution is trapped near the surface

  • Temperature: higher temperature = higher AQI because the chemical reaction that makes ozone goes faster (this is generally true but not always)

Teacher TipIn general, increased temperatures cause higher AQIs. The Smog City 2 simulation includes some complex modeling that makes this somewhat unclear. It is helpful to simplify this during the discussion.

ModificationUse an alternative discussion technique to engage students after the simulation. For example, have students stand up and move to one side of the room based on whether they think the variable will make the AQI go up or down, and have each side make an argument based on where they moved.

Step 4

4. Additional Weather Factors

Remind students that there are a few other weather factors from their glossary that may also affect air pollution. Ask students how they think the following factors affect air pollution and why. As they discuss, add these to the anchor chart:

  • Precipitation: more precipitation = lower AQI because the precipitation essentially washes out the pollution

  • Humidity (optional): higher humidity = lower AQI because it helps O3 to convert back to O2

5. Return to Investigation Tracker

Have students make notes in their investigation tracker based on big ideas they learned during this activity. Key takeaways:

  • Air pollution (especially ozone) is strongly affected by the weather

  • Weather conditions like clear sunny skies and low wind are more likely to result in a bad ozone day

  • Rain can “wash” pollution out of the air resulting in less ozone.

  • Large human populations can result in more emissions and worse air quality if they don’t do something to prevent it

6. Formative Assessment

Based upon what you learned during Smog City, what do you think the weather was like on July 9, 2018 – our Code Red Day?

  • Students should suggest low wind, high temperature, clear skies, low humidity, no rain, and possibly an inversion. The actual weather matches this well: (go back to the weather you looked up in Activity 2 for exact information)‌us/dc/KDCA/date/2018-7-9

    • High temp: 86°F

    • Fair skies throughout the day

    • Wind speed under 10mph most of the day

    • 0 precipitation


You can also put up the weather report from the warmup (or have students consider today’s weather). Based on this weather, would you expect there to be an ozone problem today?


Research Sources: If you are keeping track of research sources, you can add Smog City to the list for ways to see how different weather conditions affect air quality.

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