APES_Unit_7_Note_Slides__20-21_

7.1 Introduction to Air Pollution (Pollutants)

7.2 Learning Objectives and Essential Knowledge

• Learning Objective: STB-2.A Identify the sources and effects of air pollutants.

• Essential Knowledge:

  • Coal combustion (STB-2.A.1): Releases air pollutants including:

    • Carbon dioxide (CO2)

    • Sulfur dioxide (SO2)

    • Toxic metals (mercury, arsenic, lead)

    • Particulate matter (PM)

  • Fossil fuel combustion (STB-2.A.2): Releases nitrogen oxides (NOx) leading to:

    • Ozone production

    • Photochemical smog

    • Acid rain formation

    • Additional pollutants: carbon monoxide (CO), hydrocarbons, and PM.

  • Air quality factors (STB-2.A.3): Affected by sulfur dioxide release, especially from diesel fuels.

  • Clean Air Act (STB-2.A.4): EPA's regulations on lead in fuels reduced atmospheric lead significantly.

  • Types of air pollutants (STB-2.A.5): Distinguish between primary and secondary pollutants.

7.3 Air Pollution Basics

• Pollutant Types:

  • Gases: SO2, NOx, CO, O3, VOCs

  • Particulates: PM10 and PM2.5

• Clean Air Act (1970): Identified six criteria air pollutants for monitoring.

7.4 Air Pollutants vs. Greenhouse Gases

• CO2 Characteristics:

  • NOT classified as a criteria pollutant (though regulated per 2007 SC ruling).

  • Not harmful to immediate air quality or health but contributes to greenhouse effects.

• Key Focus for Exams: Emphasize SO2, NOx, O3, and PM over CO2 for air pollution discussions.

7.5 Primary and Secondary Air Pollutants

• Forms of Air Pollutants:

  • Primary Pollutants: Emitted directly from sources (vehicle emissions, natural events like volcanoes).

  • Secondary Pollutants: Formed through chemical reactions in the atmosphere, often in the presence of sunlight.

  • Examples: Tropospheric O3, sulfuric acid, nitric acid.

7.6 Coal Combustion and Pollution

• Pollutant Releases:

  • Coal releases higher amounts of pollutants than other fossil fuels.

  • Associated health impacts include respiratory irritants and formation of acid precipitation due to SO2.

7.7 Nitrogen Oxides (NOx) and Their Impacts

• Sources: Combustion of fossil fuels, natural processes (lightning).

• Human and Environmental Effects:

  • Respiratory irritation, photochemical smog formation, acid rain.

• Chemical Reactions Involved: NO and NO2 interconvert influenced by sunlight.

7.8 Lead and Regulation Efforts

• EPA Regulations: Lead phased out in fuels starting in 1974. Catalytic converters required in new vehicles.

• Health Impacts: Neurotoxic effects, especially in children.

7.9 Photochemical Smog

• Formation Factors (STB-2.B):

  • High temperatures, presence of NOx and VOCs leading to smog in urban areas.

  • Ozone formation peaks in the afternoon due to atmospheric chemical reactions.

• VOCs Explained:

  • Naturally occurring and human-made; trees are significant natural sources.

7.10 Mitigation of Smog

• Reduction Strategies:

  • Lowering emissions of NOx and VOCs through regulations and technology improvements.

  • Urban planning to decrease vehicle traffic and emissions.

7.11 Thermal Inversion

• Definition: Air temperature reversal trapping pollutants near ground level.

• Effects on Pollution: Higher concentrations of smog and particulates.

7.12 Indoor Air Pollutants

• Common Indoor Pollutants: Radon, carbon monoxide, VOCs, lead, asbestos, mold.

• Sources: Natural (e.g., radon from soil) vs. human-made (e.g., chemicals in furniture).

7.13 Reduction Strategies for Air Pollutants

• Methods Include:

  • Regulatory practices (e.g., Clean Air Act)

  • Technological solutions (e.g., catalytic converters, scrubbers)

  • Alternative energy sources to lower emissions.

• Community Actions: Reducing car use, conserving electricity, promoting renewable energy.

7.14 Acid Rain

• Causes: NOx and SO2 from motor vehicles and power plants.

• Environmental Effects: Acidification of soil/water, impacts on plant/animal life, corrosion of infrastructure.

7.15 Noise Pollution

• Sources and Effects:

  • Major sources include construction, traffic, and industrial noise.

  • Effects include stress responses in humans and animals, disruption of communication in wildlife.