The students talked about air pollution caused by humans today. The causes for air pollution they came up with were cars, planes, trains, manufacturing, and power plants; more specifically ones that burn fossil fuels. Another root cause, Bobby explained, is the immense population growth, which the Earth has faced in the last 200 years. All of the new people use transportation and power, which pollutes. Also they breathe, exhaling CO2. Weather is also a factor. For example, wind allows molecules to move faster, and wind pushes the pollutants around.
To model the effects of all of these things, they used a model called Smog City. An inversion layer is where warm air is unnaturally trapped between two layers of colder air. Because warm air rises, the bottom layer of colder air is unable to move, and keeps all the pollution at ground level. The model allows the students to adjust the temperature, weather, wind speed, population, and the amount of emissions produced by cars and trucks, off road, industry, and consumer products. The model showed a line graph of the ozone level throughout normal summer day. When the students ran the variables of a city like Durham, they found that the air is mostly good. The students, working in pairs, found the optimal setting for each variable, as well as the least optimal. Then, they switched which variable they would work on, and checked the other pair's results. Since some groups came up with different views, they voted on which choice was optimal.
Later the students ran simulations for various cities such as Los Angeles, using their conception of the city. They came up with their own solutions for how to solve LA's problem. Their solution ranged from solar panels or wind power, or switching cars from using gasoline to ethanol to reducing the population by any means.
The students soon switched to another computer model, which allows the user to change various parameters to model the plume of pollutants that come out of a smokestack. The students attempted to optimize the profit of their imaginary factory, while minimizing the pollution generated. They used the model, as well as a Microsoft Excel spreadsheet. They had to balance the cost of building a smokestack, with environmental concerns. One student suggested, "just putting a hole in the roof," instead of a smokestack. Using the plume model, all of the pollution would just go down into the nearby areas. However, building a 300 ft tall smokestack would cost $48 million! The groups got an imaginary allowance of either $6 or $15 million depending on how much product, and thus emissions, they were producing.