This chapter examines the influences people have on the atmosphere. These influences are broadly defined as air pollution. However, the gases associated with air pollution also occur in the atmosphere naturally. This chapter does not focus on these natural occurrences, but rather the additional gases human activities put in the air. The gases examined are carbon monoxide (CO), lead (Pb), nitrogen dioxide (NO2), ozone (O3), sulfur dioxide (SO2) , and particulate matter (PM). In the United States, the Clean Air Act created the Environmental Protection Agency (EPA) to monitor and regulate these pollutants. To accomplish this task, the EPA established the Air Quality Index (AQI) for reporting air quality. This chapter will look at data from the EPA associated with the AQI.

As city boundaries grow bigger, temperatures within the city increases. This increase in temperature is due to a reduction in vegetation and the ability of roads and buildings to capture and retain more heat than a natural environment. This increase in temperature is called an urban heat island.  We will examine these heat islands in several cities across the United States.

At this point in this overview, you may be thinking “what about carbon dioxide?” Carbon dioxide is not a pollutant in the sense it is not harmful to people or plants. Carbon dioxide is a greenhouse gas which keeps our planet warm. An excess of carbon dioxide in the atmosphere will make the planet warmer. Thus, the last section of this chapter examines the human activities that create the most carbon dioxide. In subsequent chapters, carbon dioxide will be examined in even more detail.

Chapter objectives:

1. Describe the AQI and the types of atmospheric pollutants it measures.

2. Explain the factors that produce urban heat islands.

3. Describe the carbon cycle and its importance in the climate system.

4. Identify renewable and non-renewable energy resources.

5. Describe the human activities that create the most carbon dioxide.