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Air Pollution Overview

  • Air pollution refers to the presence of harmful substances in the atmosphere.

Layers of the Atmosphere

  • Troposphere: The lowest layer where weather occurs, extending up to about 10 km.

  • Stratosphere: Above the troposphere, extending up to about 50 km; contains the ozone layer which absorbs most of the sun's harmful UV radiation.

  • Mesosphere: Above the stratosphere; temperatures decrease with altitude.

  • Thermosphere: Extends up to about 600 km; characterized by high temperatures and the presence of charged particles.

  • Exosphere/Ionosphere: Outermost layer where the atmosphere thins into space.

  • Composition: 21% oxygen, 78% nitrogen, trace amounts of other gases, and ozone.

Definition of Air Pollution

  • Air pollution is a build-up of harmful substances in the atmosphere that can impact health and the environment.

Major Sources of Air Pollution

  • Home Sources: Backyard fires, wood-burning stoves.

  • Transportation: Vehicles, diesel vehicles, SUVs, and pickups.

  • Industrial Sources: Factories, power plants, gas-powered equipment.

  • Types of Vehicles: Industrial vehicles like vans and cars contribute significantly.

Types of Air Pollutants

Anthropogenic Pollutants

  • Result from human activities and include:

    • Fossil fuel combustion

    • Industrial discharges

Natural Pollutants

  • Dust, pollen, and volcanic eruptions.

Primary and Secondary Pollutants

Primary Pollutants

  • Harmful gases and particulates released directly into the atmosphere, including:

    • Carbon monoxide (CO)

    • Nitrogen oxides (NO_x)

    • Volatile organic compounds (VOCs)

Secondary Pollutants

  • Result from chemical reactions between primary pollutants, such as:

    • Ozone (O3)

    • Photochemical smog.

Specific Pollutants

  • Carbon Monoxide (CO): Colorless, odorless, highly toxic; primarily produced from incomplete combustion.

  • Nitrous Oxides (NO_x): Result from burning organic matter and fossil fuels; colorless, odorless, can cause acid rain.

  • Sulfur Dioxide (SO2): Colorless, foul odor; major source is coal burning; can cause acid rain.

  • Volatile Organic Compounds (VOCs): Mainly hydrocarbons released from paints and fossil fuel combustion.

  • Particulate Matter (PM): Includes aerosols and suspended particles from various sources including construction and natural dust.

Environmental and Health Problems

  • Environmental issues include:

    • Acid deposition

    • Global warming

    • Ozone depletion

  • Health problems include:

    • Respiratory issues

    • Weakening of the immune system

    • Potential liver and kidney damage due to pollutants.

Factors Increasing Air Pollution

  • Tall buildings and mountains that trap pollutants.

  • High temperatures leading to thermal inversions that hold warmer air above cooler air, reducing air circulation.

Factors Decreasing Air Pollution

  • Increased wind speeds can help disperse pollutants.

  • Natural chemical reactions in the atmosphere can also reduce pollution levels.