APES - 7.1 Introduction to Atmospheric Pollution

Introduction to Air Pollution

• Definition of Pollution:

  • Pollution is a harmful material introduced into the environment affecting organisms and ecosystems, as well as human health.

  • Discusses both anthropogenic (human-caused) pollution and natural sources (e.g., forest fires, volcanoes).

Types of Air Pollutants

• Primary vs. Secondary Pollutants:

  • Primary Pollutants: Emitted directly from sources (e.g., tailpipes, smokestacks).

  • Secondary Pollutants: Formed by transformations of primary pollutants in the atmosphere; can be more harmful.

Major Air Pollutants and Their Sources

• Sulfur Dioxide (SO2):

  • Source: Combustion of coal, oil, gasoline, and diesel.

  • Characteristics: Corrosive gas, respiratory irritant, detectable smell at low concentrations.

  • Health Effects: Can exacerbate respiratory illnesses and damage lung tissue.

• Nitrogen Oxides (NOx):

  • Forms: Nitric oxide (NO) and nitrogen dioxide (NO2).

  • Source: Combustion of fossil fuels, especially in transportation and energy production.

  • Impacts: Contributes to photochemical smog and reduces crop yields; adverse effects on vegetation.

• Carbon Monoxide (CO):

  • Characteristics: Colorless, odorless, toxic gas.

  • Sources: Incomplete combustion in household appliances, vehicles, urban air pollution.

  • Health Effects: Binds to hemoglobin, impeding oxygen transport in the body; can be fatal at high levels.

• Particulate Matter (PM):

  • Composition: Small airborne particles that can cause respiratory issues.

  • Classification: PM10, PM2.5, PM1 based on size, with smaller particles being more dangerous.

  • Sources: Agricultural activities, combustion processes, traffic emissions.

Heavy Metals in Air Pollution

• Lead (Pb):

  • Previously used in gasoline; significant neurotoxin affecting children’s development.

  • Sources: Old paints, former gasoline additives.

• Mercury (Hg):

  • Found in coal and oil; enters the atmosphere through waste incineration.

  • Bioaccumulation in food chains; dangerous effects on human health.

Volatile Organic Compounds (VOCs)

• Description: Hydrocarbons that vaporize easily.

• Sources: Industrial solvents, vehicle emissions, household products.

• Health Impacts: Contribute to smog formation; harmful to human health.

Legislative Framework Governing Air Quality

• Clean Air Act (1970):

  • Aimed to regulate air pollutants through establishing the EPA and National Ambient Air Quality Standards (NAAQS).

  • Criteria Air Pollutants: Nitrogen oxides, ozone, sulfur dioxide, carbon monoxide, lead, particulate matter.

• Cap-and-Trade Program (1990 Amendment):

  • Enables industries to trade pollution allowances, incentivizing reduction of emissions at lower costs.

  • Evidence of significant reduction in sulfur emissions post-implementation of cap-and-trade.

Air Quality Improvements and Sources of Pollutants

• Pollutant Sources:

  • Different sources attributed to specific pollutants (e.g., industrial processes, vehicle emissions).

• Effectiveness of Clean Air Act:

  • Significant reductions in levels of pollutants (e.g., lead emissions reduced from over 200,000 tons in 1970 to negligible levels by 2014).