AP Environmental Science — Unit 7: Atmospheric Pollution

What AP Environmental Science Unit 7 covers

The College Board Course and Exam Description breaks Unit 7 into 8 topics:

1. 7.1 Introduction to Air Pollution
2. 7.2 Photochemical Smog
3. 7.3 Thermal Inversion
4. 7.4 Atmospheric CO2 and Particulates
5. 7.5 Indoor Air Pollutants
6. 7.6 Reduction of Air Pollutants
7. 7.7 Acid Rain
8. 7.8 Noise Pollution

AP Environmental Science Unit 7 practice questions

• What is a PRIMARY air pollutant?

  A pollutant emitted directly from a source in its harmful form. Examples: SO₂ from coal, CO from vehicle exhaust.

• What is a SECONDARY air pollutant? Give one example.

  A pollutant formed when primary pollutants react. Example: ground-level ozone (O₃) from NOₓ + sunlight.

• Coal combustion at a power plant releases which air pollutants directly into the atmosphere?

  CO₂, SO₂, toxic metals, and particulates. Mercury is a key toxic metal released by coal.

• The Clean Air Act directed the EPA to regulate lead in fuels. What was the measurable environmental outcome?

  Atmospheric lead concentrations dropped dramatically. That cut human exposure and the neurological damage lead causes.

• What THREE ingredients are required to form photochemical smog?

  Nitrogen oxides (NOₓ), VOCs, and sunlight. Heat and UV radiation drive the reaction.

• In a city with heavy traffic, NOₓ spikes at 7 AM. When do ground-level ozone concentrations typically peak, and why?

  Ozone peaks in the afternoon, after hours of sunlight react. It needs accumulated NOₓ and VOCs plus UV.

• What are Volatile Organic Compounds (VOCs) and name TWO sources — one natural, one human-made.

  VOCs are organic chemicals that evaporate or sublimate at room temperature. Natural source: trees (e.g., pine). Human-made source: gasoline or formaldehyde in building materials.

• A city wants to reduce photochemical smog. Which TWO categories of emissions should be targeted for reduction?

  Nitrogen oxides (NOₓ) and VOCs. Cutting either limits the reactions that form photochemical smog.

+ 20 more AP Environmental Science cards in the app.

Key terms in Unit 7

These 12 terms show up in the Unit 7 cards. Each one links to its definition in the AP Environmental Science key-term reference.

• Acid deposition
• Buffering capacity
• Carbon monoxide (CO)
• Catalytic converter
• Clean Air Act
• Indoor air pollutants
• Noise pollution
• Photochemical smog
• Secondary pollutant
• Thermal inversion
• Vapor recovery nozzle
• Volatile organic compounds (VOCs)