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United StatesEnvironmental Science

Unit 7: Atmospheric Pollution

8 dot points across 8 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How does burning coal and fuel turn rain acidic, and what does that acid do downwind?

Topic 7.7 Acid Rain: explain how acid rain forms from sulfur and nitrogen oxides and describe its environmental impacts.
A focused answer to APES Topic 7.7, covering how acid deposition forms from sulfur dioxide and nitrogen oxides, the pH scale, the impacts on lakes, forests, soils and buildings, the transboundary nature of the problem, and how to reduce it, with a worked pH calculation.
10 min answer →

Where do the carbon dioxide and tiny particles in the air come from, and why does particle size matter?

Topic 7.4 Atmospheric CO2 and Particulates: describe the natural and human sources of atmospheric carbon dioxide and particulate matter and their effects.
A focused answer to APES Topic 7.4, covering the natural and human sources of atmospheric carbon dioxide and particulate matter, the difference between PM10 and PM2.5, why fine particles are most dangerous, the health and environmental effects, with a worked particulate exposure calculation.
9 min answer →

Why can the air inside a home be more polluted than the air outside?

Topic 7.5 Indoor Air Pollutants: identify the major indoor air pollutants and their sources and explain why indoor air pollution is a serious health risk.
A focused answer to APES Topic 7.5, covering the major indoor air pollutants (carbon monoxide, radon, asbestos, VOCs, particulates from biomass burning, mold, lead), their sources, why indoor air pollution is so dangerous in developing and developed countries, and how to reduce it, with a worked radon risk reasoning example.
9 min answer →

Where does air pollution come from, and what is the difference between pollution made directly and pollution made in the air?

Topic 7.1 Introduction to Air Pollution: identify the major air pollutants and their sources and distinguish primary from secondary pollutants.
A focused answer to APES Topic 7.1, covering the major air pollutants, their natural and human sources, the criteria pollutants, and the distinction between primary and secondary pollutants, with a worked emissions calculation.
9 min answer →

How can unwanted sound harm people and wildlife, and how is it measured?

Topic 7.8 Noise Pollution: identify the sources of noise pollution and describe its effects on humans and wildlife.
A focused answer to APES Topic 7.8, covering the sources of noise pollution, the decibel scale, the effects on human health and on wildlife (stress, hearing damage, disrupted communication and migration), and how to reduce it, with a worked decibel reasoning example.
9 min answer →

Why does a brown haze form over cities on hot, sunny days?

Topic 7.2 Photochemical Smog: explain how photochemical smog forms from nitrogen oxides, volatile organic compounds and sunlight, and describe its impacts.
A focused answer to APES Topic 7.2, covering how photochemical smog forms from nitrogen oxides, volatile organic compounds and sunlight, the role of ground-level ozone, the conditions that worsen it, its health and environmental impacts, with a worked ozone-formation reasoning example.
9 min answer →

How can we clean up the air we have already polluted, and stop pollution at the source?

Topic 7.6 Reduction of Air Pollutants: describe methods used to reduce air pollution, including regulation, scrubbers, catalytic converters and cleaner fuels.
A focused answer to APES Topic 7.6, covering methods to reduce air pollution including the Clean Air Act and regulation, scrubbers and electrostatic precipitators, catalytic converters, vapor recovery, cleaner fuels and renewable energy, with a worked scrubber efficiency calculation.
9 min answer →

Why does a layer of warm air sometimes trap pollution close to the ground?

Topic 7.3 Thermal Inversion: explain how a thermal inversion forms and why it traps air pollution near the ground.
A focused answer to APES Topic 7.3, covering how a thermal inversion forms, why it reverses the normal temperature profile, how it traps pollutants near the surface, the role of topography, and its link to severe smog events, with a worked reasoning example.
9 min answer →