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Science Panda - AP Environmental

Unit 7 Review - Air Pollution

Intro to Air Pollution

Air pollutants can be primary or secondary.

Many air pollutants come from burning fossil fuels.

  • SOx – Sulfur oxides like SO2 (sulfur dioxide)

  • NOx – Nitrogen oxides like NO2 (cars)

  • CO2 (respiration, combustion, volcanoes)

  • Toxic metals like lead and mercury

  • Particulate Matter (coal, cigarette smoke, fires, etc.)

The Clean Air Act (CAA) regulates many air pollutants, particularly lead in fuel, leading to a dramatic decrease.

Photochemical Smog

Smog forms when NOx react with oxygen and then sunlight to form photochemical oxidants.

  • NOx is formed early in the day from car emissions (rush hour) and then reacts in sunlight to form O3.

  • Smog often forms in urban areas.

  • If VOCs are present, smog can then form.

  • VOCs are chemicals in gasoline, formaldehyde, varnishes, tree sap, etc., that evaporate at room temperature and often have strong odors.

The environment can affect smog formation (temperature, weather patterns, valleys).

Thermal Inversions

Acid Deposition

Acid deposition (both rain and dry) is due to nitrogen oxides and sulfur oxides.

  • NOx and SOx create secondary pollutants nitric acid and sulfuric acid in the atmosphere when mixing with water vapor.

  • Acid rain can affect locations far away from their source.

  • Acid deposition can lead to acidification of soils and water bodies (limestone in soils helps to neutralize acids), damage to trees and corrosion of buildings and statues, may leach toxic metals from the ground.

Indoor Air Pollutants

Come from natural & man-made sources as well as combustion.

  • Natural: Radon (radioactive), mold, dust

  • Particulates: asbestos, dust, pollen

  • Man-Made: insulation, VOCs from furniture, paneling, carpets, formaldehyde, lead from paint

  • Combustion: CO, NOx, SOx, PM, smoke

Carbon Monoxide (CO) is an asphyxiant, deadly to humans.

Indoor Air Pollutants - Radon

Radon-222 is naturally occurring and radioactive.

  • Produced by decay of uranium found in the ground.

  • Radon enters homes through soil, cracks in foundations/walls as it moves up through soil.

  • Radon exposure can lead to lung cancer because it damages the lining of the lungs, 2nd leading cause in US.

Noise Pollution

Noise pollution is sound at a level that can cause hearing loss and physiological stress.

  • Sources: traffic transportation, construction, domestic activity, aircraft, industrial activity.

  • Effects on humans: insomnia, poor concentration, loss of productivity, loss of hearing, stress, can affect physical health.

  • Effects on environment: animals alter behavior, may relocate, and change migration routes, can’t communicate.

  • Animals in the ocean can even be affected by boat noise, sonar, and drilling.

Reduction of Air Pollutants

  • Catalytic Converters: in vehicles, convert NOx and CO to less harmful chemicals.

  • Vapor Recovery Nozzles: on gasoline pumps, capture fumes (VOCs).

  • Scrubbers: remove pollutants to keep them out of the atmosphere.

  • Electrostatic Precipitators: remove particulates before they leave a coal-burning power plant’s chimney.

  • Reducing fossil fuel use in general.

  • Regulatory methods, such as laws like the Clean Air Act in the USA.