Free Response Questions (College Board AP® Environmental Science): Exam Questions

25 mins3 questions
1a
1 point
Diagram showing temperature inversion in a city: cool air is trapped in a valley, smog builds up under a warm air layer, with pollutants released below.
A diagram showing a temperature inversion trapping pollutants in a valley.

The city of Los Altos is located in a valley surrounded by mountains. Despite reducing emissions from vehicles and industries, the city continues to suffer from frequent photochemical smog episodes, especially in winter months. Residents report increased respiratory issues and reduced visibility.

Identify the primary pollutant involved in the formation of photochemical smog.

1b
1 point

Describe the chemical reaction that leads to the formation of tropospheric ozone.

1c
1 point

Using the image, explain how thermal inversion traps pollutants near the ground.

1d
1 point

Describe one human health impact of photochemical smog.

1e
1 point

Identify one natural factor that worsens smog formation in cities like Los Altos.

1f
1 point

Propose one urban planning strategy to reduce photochemical smog.

1g
1 point

Explain the role of volatile organic compounds (VOCs) in the formation of photochemical smog.

1h
1 point

Describe one way climate and topography influence the severity of smog.

1i
1 point

Explain how reducing NOₓ emissions could affect smog levels.

1j
1 point

Describe one reason public education campaigns are important in managing air pollution.

2a
1 point

A health agency is investigating increased respiratory illness reports in a low-income urban neighborhood. Homes are older, poorly ventilated, and located near busy roads. Inspections found high levels of radon-222 gas, particulates, and volatile organic compounds (VOCs).

Identify one natural source and one anthropogenic source of indoor air pollution.

2b
1 point

Describe how radon-222 gas enters homes.

2c
1 point

Explain one health risk associated with radon-222 exposure.

2d
1 point

Describe one indoor source of VOCs and their impact on health.

2e
1 point

Explain why low-income communities may experience higher exposure to indoor pollutants.

2f
1 point

Identify one air pollutant commonly released by indoor combustion and describe its effect.

2g
1 point

Describe one method to reduce radon exposure in homes.

2h
1 point

Propose a strategy to reduce VOCs in indoor air.

3a
1 point

Particulate matter (PM) originates from both natural and human-made sources, contributing to environmental and human health concerns. Scientists are particularly concerned about PM2.5 emissions from wildfires. 

Describe the relationship displayed on the graph.

Line graph of yearly and 5‑year average forest area burned (km²) from 1984–2020, showing fluctuating values with a clear long‑term upward trend.
3b
1 point

Describe how fire can be used as a forest management tool.

3c
1 point

In 2020, wildfires emitted 40 million metric tons of particulate matter. In 2021, the amount increased to 55 million metric tons. Calculate the percent change in particulate matter emissions from wildfires between these two years. 

3d
1 point

A region’s coal-burning power plant emits 25 million metric tons of particulate matter annually. If wildfires in the same region released 60 million metric tons in a particularly bad fire season, calculate the percent difference in emissions between wildfires and industry?

3e
1 point

An average adult breathes approximately 11m3 of air per day. If the concentration of fine particulate matter PM2.5 in the air is 35 micrograms per cubic meter (µg/m³), calculate the mass of  (in milligrams)  PM2.5 a person inhales in a day? (1 microgram µg = 0.001 milligrams mg)

3f
1 point

Identify one strategy to reduce the amount of particulate matter from burning coal.

3g
1 point

Describe one drawback of the strategy you described in (f)