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Unit 7 · Atmospheric Pollution Unit Hub Flashcards Cheat Sheet Essentials Visual Review MC Practice FRQ Practice

AP Environmental Science Unit 7 Essentials

The must-know terms and big ideas for Unit 7: Atmospheric Pollution. Every vocabulary word and concept you need to master.

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Big Idea 1
Most major air pollutants trace back to combustion
Vehicle exhaust and power plant emissions are the common source behind photochemical smog (NOx + VOCs), particulate matter, and acid rain (SO2 + NOx). Recognizing combustion as the shared root cause helps you predict that solutions targeting one pollutant (like cleaner-burning engines) often reduce several pollutants at once.
Combustion Smog Acid Rain
Big Idea 2
Weather and geography can trap or disperse pollution independent of emission levels
Thermal inversions and valley terrain can dramatically worsen air quality even without any change in how much pollution is being emitted, simply by preventing it from dispersing upward and away. This is why the same city can have very different air quality on different days — the difference is often weather, not emissions.
Thermal Inversion Geography Smog
Big Idea 3
Pollution doesn't stay where it's emitted — and indoor air has its own unique risks
Acid rain precursors can travel hundreds of miles before falling as precipitation, meaning the country or region that emits SO2/NOx is often not the one that suffers the ecological damage. Meanwhile, indoor air pollutants like radon, carbon monoxide, and asbestos pose risks entirely separate from outdoor air quality, requiring their own detection and mitigation strategies.
Acid Rain Indoor Air Radon
Primary pollutant
A pollutant emitted directly into the atmosphere from a source.
Air Pollution
Secondary pollutant
A pollutant formed when primary pollutants react chemically in the atmosphere, such as ground-level ozone.
Air Pollution
Photochemical smog
Air pollution formed when sunlight reacts with NOx and VOCs (mostly from vehicles) to produce ground-level ozone.
Smog
Ground-level ozone
A harmful secondary pollutant and lung irritant formed near the surface, distinct from protective stratospheric ozone.
Smog
VOCs (volatile organic compounds)
Carbon-containing chemicals that evaporate easily, contributing to smog formation.
Smog
Thermal inversion
A weather condition where warm air traps cooler air (and pollutants) near the ground, preventing normal dispersion.
Weather
Particulate matter (PM)
Tiny solid or liquid particles suspended in air; PM2.5 (fine) is more dangerous than PM10 (coarse) due to deeper lung penetration.
Particulates
Radon
A naturally occurring, colorless, odorless radioactive gas that can accumulate indoors and cause lung cancer.
Indoor Air
Carbon monoxide (CO)
A colorless, odorless gas that binds to hemoglobin more readily than oxygen, posing a poisoning risk indoors.
Indoor Air
Asbestos
A fibrous mineral once used in building materials; inhaling its fibers can cause lung scarring and cancer.
Indoor Air
Catalytic converter
A vehicle exhaust device that converts harmful pollutants into less harmful substances using a catalyst.
Reduction
Scrubber
A device, often in smokestacks, that removes particulates and gases from exhaust before release.
Reduction
Clean Air Act
A major U.S. federal law setting national air quality standards to regulate emissions.
Reduction
Acid rain
Acidic precipitation formed when SO2 and NOx react with atmospheric water vapor, damaging soil and aquatic ecosystems.
Acid Rain
Noise pollution
Excessive or disruptive sound levels that can damage hearing and disrupt human and wildlife behavior.
Noise