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Section 12.1 Air Pollution

Air pollution refers to any gases or particulates (harmful to human health and/or to the environment) released by human activities.

  • EPA considers 6 criteria pollutants

    • CO

    • N oxides

    • S oxides

    • ground-level ozone (O\(_3\))

    • particulate matter (PM)

    • lead

Acid Rain

  • falling of acids and acid-forming compounds from Earth’s atmosphere to its surface

  • can be dry particles or as wet deposition as acid rain, snow, fog, or dew

  • formed when oxides of nitrogen and sulfur combine with water vapor or liquid water to produce nitric acid and sulfuric acid

  • normal pH of precipitation is 5.5, slightly acidic (mostly from carbonic acid); acid rain can lower pH to 4–4.5

  • damage to structures, plants, aquatic life, ecosystems

Stratospheric Ozone

  • reduced amounts of ozone over Antarctic

  • occurs in the Antarctic spring (October)

  • result of the chlorine in CFCs (released by UV dissociation)

    • Antarctic atmosphere is very cold causing formation of polar stratospheric clouds (destruction is enhanced in these clouds)

    • Polar vortex prevents mixing

  • Expected repair itself over time now that CFC use is limited

  • Montreal Protocol: 1989

    • phasing out of ozone-depleting substances

    • EECL: Effective equivalent chlorine