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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.