Air Pollution Notes

Overview of Air Pollution

  • Major sources of air pollution impact both the environment and human health.

Key Vocabulary

  • Acid precipitation
  • Smog
  • Particulate
  • Aerosol
  • Fly ash
  • Chlorofluorocarbon (CFC)
  • Halon
  • Ozone hole

Historical Context

  • 1948, Donora, PA incident: 20 deaths due to pollution from factories producing steel and sulfuric acid, leading to the Clean Air Act of 1963.

Sources of Air Pollution

  • Emission of gases from burning fossil fuels:
    • Ideal combustion: releases CO_2 and water.
    • Impurities lead to pollutants like sulfur oxides and nitrogen oxides.
    • Incomplete combustion creates benzene, methane, and carbon monoxide.

Acid Rain

  • Natural rain has a pH of 5.7; acid rain can drop to pH 1.7.
  • Consequences:
    • Human health: Impaired lung, heart, and liver function.
    • Property damage: Erosion of limestone and marble.
    • Ecological damage: Depletion of nutrients and increased water acidity.

Smog and Ozone

  • Smog: Brown haze causing eye irritation and crop damage.
  • Ozone formation:
    • Resulting from nitrogen oxides, oxygen, and incomplete combustion.
    • Dual role: beneficial in stratosphere, pollutant in troposphere.

Other Pollutants

  • Toxic volatiles: Organic chemicals from industrial processes.
  • Particulates: Solid matter like dust and soot.
  • Aerosols: Particles suspended in air.
  • Fly ash: Dust from burning coal.

Ozone Layer Depletion

  • CFCs linked to ozone depletion, first reported in 1985.
  • Ban on CFCs initiated due to their harmful effects; concentrations have declined since 1995.

Types of Pollutants

  • Primary: Emitted directly from the source.
  • Secondary: Formed through atmospheric chemical reactions.