Students are introduced to the concept of air quality by investigating the composition, properties, atmospheric layers and everyday importance of air. They explore the sources and effects of visible and invisible air pollution. By learning some fundamental meteorology concepts (air pressure, barometers, prediction, convection currents, temperature inversions), students learn the impact of weather on air pollution control and prevention. Looking at models and maps, they explore the consequences of pollutant transport via weather and water cycles. Students are introduced to acids, bases and pH, and the environmental problem of acid rain, including how engineers address this type of pollution. Using simple models, they study the greenhouse effect, the impact of increased greenhouse gases on the planet's protective ozone layer and the global warming theory. Students explore the causes and effects of the Earth's ozone holes through an interactive simulation. Students identify the types and sources of indoor air pollutants in their school and home, evaluating actions that can be taken to reduce and prevent poor indoor air quality. By building and observing a few simple models of pollutant recovery methods, students explore the modern industrial technologies designed by engineers to clean up and prevent air pollution.